Abstract

We report on the development of a novel laser crystal with broadband emission properties at ∼2 µm – a Tm3+,Li+-codoped calcium tantalum gallium garnet (Tm:CLTGG). The crystal is grown by the Czochralski method. Its structure (cubic, sp. gr. $Ia\bar{3}d$, a = 12.5158(0) Å) is refined by the Rietveld method. Tm:CLTGG exhibits a relatively high thermal conductivity of 4.33 Wm-1K-1. Raman spectroscopy confirms a weak concentration of vacancies due to the charge compensation provided by Li+ codoping. The transition probabilities of Tm3+ ions are determined using the modified Judd-Ofelt theory yielding the intensity parameters Ω2 = 5.185, Ω4 = 0.650, Ω6 = 1.068 [10−20 cm2] and α = 0.171 [10−4 cm]. The crystal-field splitting of the Tm3+ multiplets is revealed at 10 K. The first diode-pumped Tm:CLTGG laser generates 1.08 W at ∼2 µm with a slope efficiency of 23.8%. The Tm3+ ions in CLTGG exhibit significant inhomogeneous spectral broadening due to the structure disorder (a random distribution of Ta5+ and Ga3+ cations over octahedral and tetrahedral lattice sites) leading to smooth and broad gain profiles (bandwidth: 130 nm) extending well above 2 µm and rendering Tm:CLTGG suitable for femtosecond pulse generation.

© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

1. Introduction

An ordered crystal is an ideal solid state material exhibiting lattice periodicity in all directions. The certain arrangement of atoms in the unit-cell is repeated forming a translationally invariant crystal structure in the long-range. A disorder of the structure denotes some deviation from a perfect crystalline order. Weak disorder can be represented as a perturbation of the crystalline structure, e.g., caused by dopants, defects, vacancies and / or dislocations. Strong disorder is a pronounced departure from the crystalline order. The length scale over which order, or disorder persists is also relevant. The local disorder can be revealed at a length of several unit-cells.

In laser physics, structurally disordered crystals constitute an important class of gain materials [1]. In such crystals, one or several host-forming cations are randomly distributed over two or more different crystallographic sites. Two situations for the dopant (laser-active) ions can be thus distinguished: (i) the dopant ions are distributed over several lattice sites [1] or (ii) they are present at one site while other cations experience a random site distribution [2]. In both cases, the spectral bands of dopant ions will experience an inhomogeneous broadening either due to the presence of several crystal-fields or due to the different cation multi-ligands around the dopant ions. Such spectral broadening is favorable for broad tuning of the laser wavelength and / or the generation of ultrashort pulses in mode-locked (ML) lasers. Note that there also exists compositional disorder in “mixed” (solid-solution) materials A1-xBx, even when the parent compounds (A and B) are ordered [3]. This also results in spectral broadening. The main drawback of disordered crystals is the deterioration of their thermal properties which justifies the search for such crystals with high thermal conductivity.

Among the host crystals for doping with laser-active rare-earth ions (RE3+), cubic multicomponent garnets with general chemical formula {A}3[B]2(C)3O12 where A = Y, Gd, Lu or Ca, Mg, Fe, Sr, etc., and B and C = Al, Sc, Ga, Ta, etc., occupy a special position. Note that the ordered garnet Y3Al5O12 (YAG) is the most widespread laser host crystal. Crystals belonging to the cubic garnet family combine good thermo-mechanical behavior with attractive spectroscopic properties of the dopant RE3+ ions. They are optically isotropic. Finally, cubic garnets can be grown by the well-developed Czochralski (Cz) method.

Among the structurally disordered multicomponent garnets, calcium niobium gallium garnet (CNGG) is one of the best-known representatives [4,5]. The structure disorder of CNGG originates from a random distribution of Nb5+ and Ga3+ cations over [B] and (C) lattice sites leading to a significant inhomogeneous broadening of the emission bands of the RE3+ dopant ions. The latter are expected to replace for the divalent Ca2+ cations; the charge compensation is provided by vacancies [6] or by intentional codoping by univalent alkali ions (Na+, Li+ or their combination) [7,8] further affecting the spectral broadening [9].

Recently, CNGG-type crystals doped with thulium (Tm3+) [10] and holmium (Ho3+) [11] ions have proven to be very suitable for the generation of sub-100 fs pulses at ∼2 µm owing to their smooth and very broad gain profiles extending beyond the structured water vapor air absorption [12] which is essential for the broadband ML laser performance. Pan et al. reported on a Tm,Na:CNGG (Tm:CNNGG) laser mode-locked by a single-walled carbon nanotube saturable absorber (SA) delivering 84-fs pulses at 2018nm [10]. In the continuous-wave (CW) regime, a broad tuning range of 1879–2086nm was achieved in the same work [10]. Zhao et al. achieved shorter pulses (67 fs, i.e., 10 optical cycles at 2083nm) from a Tm,Ho,Li:CNGG (Tm,Ho:CLNGG) laser ML by the same SA utilizing the combined gain bandwidths from both active ions [13].

There exists another disordered multicomponent garnet similar to CNGG, namely calcium tantalum gallium garnet (CTGG) [14]. Ma et al. have shown that CTGG exhibits higher thermal conductivity (κ = 3.76 Wm-1K-1) as compared to its niobium counterpart [14]. CTGG-type crystals doped with Nd3+ and Yb3+ ions have been studied for laser operation at ∼1 µm [15,16]. However, no lasing in the ∼2 µm spectral range has been reported so far.

In the present work, we reveal the potential of Tm3+, Li+-codoped CTGG (abbreviated Tm:CLTGG) as a broadband laser gain material at ∼2 µm and beyond.

2. Crystal growth

A Tm:CLTGG single crystal was grown by the Czochralski (Cz) method in an iridium crucible using argon atmosphere. The starting materials, CaCO3 (purity: 4N), Ta2O5, Ga2O3, Li2CO3 and Tm2O3 (purity: 5N), were weighed according to the following chemical formula: Ca3Ta1.88Li0.20Ga2.80O12·0.05Tm3Ga5O12. To compensate the volatilization of Ga2O3 during the synthesis of the polycrystalline material and the crystal growth, an excess of 1.0 wt% Ga2O3 was used. Larger excess of Ga2O3 violates the composition of the crystal and affects its optical quality. The equation of the chemical reaction reads: 3CaCO3 + 0.94Ta2O5 + 1.525Ga2O3 + 0.075Tm2O3+ 0.1Li2CO3 → Ca3Ta1.88Li0.20Ga2.80O12·0.05Tm3Ga5O12 + 3.1CO2↑.

The raw materials were mixed, ground and heated at 900 ℃ for 10 h in a platinum crucible to decompose CaCO3. After cooling down the crucible to room temperature (RT, 20 ℃), the mixture was pressed into tablets and reheated at 1200 ℃ for 15 h to form the cubic garnet phase through a solid-state reaction. The synthesized polycrystalline material was placed in an iridium crucible and melted by an intermediate-frequency heater. The first crystal was grown using an [111] oriented seed from undoped YAG. From this first crystal, another seed with the same orientation was cut and used for the growth of laser-quality crystals. During the crystal growth, the pulling rate varied from 0.5 to 1.0 mm/h and the crystal rotation speed was kept at 8 to 15 revolutions per minute. Once the growth was completed, the crystal was removed from the melt and cooled down to RT at a stepped rate of 15 to 25 ℃/h. The crystal was annealed in air, the maximum temperature was 1200 ℃ and the hold duration was 24 h, the heating and cooling rates were about 50 ℃/h.

Figure 1 shows a photograph of an as-grown Tm:CLTGG crystal boule. It has a cylindrical shape (diameter: 20 mm, length of the central part: 30 mm). The crystal does not contain cracks and inclusions and no scatter centers are seen under illumination by a He-Ne laser indicating good optical quality. The as-grown crystal shows a light greenish coloration. The surface of the boule is translucent probably due to the volatilization of Ga2O3 during the crystal growth (it may attack the surface of the crystal that is pulled over the melt). The internal part of the crystal exhibits excellent transparency, Fig. 1(b).

 figure: Fig. 1.

Fig. 1. (a) Photograph of the as-grown Tm:CLTGG crystal boule, the growth direction is [111]; (b) photograph of a polished laser element.

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By using X-ray fluorescence, the actual concentration of Tm3+ ions was measured to be 3.17 at.% with respect to Ca2+ ions (NTm = 5.03×1020 cm-3) leading to a segregation coefficient KTm of 0.67. The targeted doping concentration of ∼3 at.% Tm was selected due to the spectroscopic considerations. It could be further increased by changing the Tm content in the growth batch considering the determined KTm value.

3. Crystal structure

3.1 X-ray diffraction

The X-ray powder diffraction (XRD) pattern was measured at RT using a Bruker D2 Phaser diffractometer, Cu Kα1 radiation (1.54184 Å) with a step size of 0.02° and a step time of 1.0 s, in the range of 2θ from 10° to 90°. The measured diffraction pattern, Fig. 2(a), agrees well with the theoretical one for cubic Al1.23Ca3Fe0.99Hf2Si0.99O12 garnet (Crystallography Open Database (COD) card #96-901-3967). No other phases are found.

 figure: Fig. 2.

Fig. 2. X-ray powder diffraction study of Tm:CLTGG: (a) XRD pattern, (hkl) are Miller’s indices, vertical bars – theoretical pattern for Al1.23Ca3Fe0.99Hf2Si0.99O12 garnet; (b) Rietveld structure refinement: experimental (black), calculated (red) and differential (blue) XRD profiles, vertical dashes mark the Bragg reflections.

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The structure of Tm:CLTGG was refined using the Rietveld method. The Match3! software was used and a total of 196 reflections were analyzed. The obtained reliability factors are Rp = 4.94%, Rwp = 6.38%, Rexp = 2.21% and the reduced chi squared χ2 = (Rwp/Rexp)2 = 8.37. Tm:CLTGG crystallizes in the cubic class (sp. gr. $Ia\bar{3}d$, No. 230) with a lattice constant a = 12.5158(0) Å, the volume of the unit-cell is V = 1960.54 Å3, the calculated density is ρcalc = 5.893 g/cm3 and the number of formula units in the unit-cell is Z = 8. The fractional atomic coordinates, the site occupancy factors (O.F.) and the isotropic displacement parameters obtained during the Rietveld refinement are listed in Table 1.

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Table 1. Fractional Atomic Coordinates, Occupancy Factors and Isotropic Displacement Parameters for Tm:CLTGG Crystal

The structure of Tm:CLTGG is illustrated in Fig. 3. This crystal belongs to the family of multicomponent garnets with a general formula {A}3[B]2(C)3O12, where {A}, [B], and (C) stand for dodecahedral (Wyckoff symbol: 24c), octahedral (16a) and tetrahedral (24d) sites, respectively [5]. The stoichiometric CTGG, in analogy to CNGG [4], is expected to have a chemical formula of Ca3Ta1.5Ga3.5O12 which is equivalent to {Ca3}[Ta1.5Ga0.5](Ga3)O12. The composition of the real crystal (even undoped) deviates from the stoichiometric one. The Ca2+ cations are located in the {A} sites.

 figure: Fig. 3.

Fig. 3. Crystal structure of Tm:CLTGG: (a) projection of the crystal structure parallel to the a-c plane; (b) the variety of cationic distributions around Ca2+ | Tm3+ ions occupying the dodecahedral 24c sites: nearest-neighbor cations at: (i) dodecahedral 24c sites, (ii) octahedral 16a sites and (iii) tetrahedral 24d sites.

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The Tm3+ ions replace for the Ca2+ ones (the corresponding ionic radii are RCa = 1.12 Å and RTm = 0.994 Å for VIII-fold oxygen coordination). In the [Ca|TmO8] dodecahedrons, there are four shorter (2.3966(2) Å) and four longer (2.5577(0) Å) metal-to-oxygen (M-O) interatomic distances. The Ta5+ and Ga3+ cations are randomly distributed over the [B] and (C) sites with VI-fold and IV-fold oxygen coordination, respectively, according to the occupancy factors listed in Table 1. The M-O bond lengths are 1.990(0) Å (×6) and 1.8526(1) Å (×4), respectively. The Li+ ion incorporation in this garnet takes place only at 24d sites. The charge compensation is ensured by both, Li+ ions and cationic vacancies □ in the 24c and 24d sites. Their calculated percentages are 0.6% and 2.8%, respectively. The chemical formula of the crystal can be thus expressed as follows:{Ca2.889Tm0.0930.018}[Ta1.32Ga0.68](Ga2.367Ta0.204Li0.3450.084)O12.

In the Tm:CLTGG structure, each [Ca|TmO8] dodecahedron shares edges with four other dodecahedra where the shortest interatomic distance Ca|Tm―Ca|Tm is 3.8321(1) Å, and it is surrounded by four corner-sharing octahedra (Ta5+ and Ga3+ at 16a sites) and by six tetrahedra (Ga3+, Ta5+ and Li+ at 24d sites), two of them sharing edges, and the remaining four being connected by shared corners.

3.2 Raman spectroscopy

The Raman spectrum of Tm:CLTGG was measured using a Renishaw inVia confocal Raman microscope with a ×50 Leica objective and an Ar+ ion laser (514 nm). It is shown in Fig. 4. In the same figure, for comparison, we also show the Raman spectrum of its niobium isomorph, Tm:CLNGG. A total of 18 bands are resolved in the Raman spectrum of Tm:CLTGG. Among them, the vibrations at high frequencies (700-900 cm-1) forming two broad bands are typically analyzed as they are sensitive to the alteration of the structure of multicomponent garnets [4,5]. They are assigned to internal vibrations (symmetric stretching modes, νs) of [M2O4] tetrahedra (M2 = Ga2 and Ta2). In our case, the tetrahedral sites (24d) are occupied by Ta5+ and Ga3+ cations. The band at lower frequencies with two local maxima at 748 cm-1 (C1) and 772 cm-1 (C2), is assigned to the [Ga2O4] groups and it is only slightly distorted with respect to that in the Tm:CLNGG crystal. The band at higher frequencies, at 842 cm-1 (C4), is due to the [Ta2O4] groups. The latter does not split, possesses much weaker intensity and is shifted to higher frequencies as compared to that in Tm:CLNGG crystal with [Nb2O4] groups. The lack of the long-frequency component of the second band indicates weak structural distortion of the [Ta2O4] tetrahedra and weak content of cationic vacancies, in agreement with the XRD study. This highlights the positive role of Li+ ions in the charge compensation.

 figure: Fig. 4.

Fig. 4. Unpolarized RT Raman spectrum of the Tm:CLTGG crystal, λexc = 514 nm. Numbers indicate the band frequencies in cm-1. The Raman spectrum of Tm:CLNGG is given for comparison.

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4. Thermal properties

The specific heat Cp and the thermal diffusivity λ were measured using a laser flash apparatus (NETZSCH LFA457). For this, a squared wafer with dimensions of 4×4×1 mm3 was cut from the Tm:CLTGG crystal along the [111] direction and double side coated with graphite.

The dependence of the specific heat (Cp) of Tm:CLTGG on temperature is shown in Fig. 5(a). The Cp value increases monotonously with temperature, from 0.57 to 0.66 J g-1 K-1, when the temperature is increased from 298.2 K to 571.9 K. Figure 5(b) shows the measured thermal diffusivities (λ). The λ value along the [111] direction decreases with temperature. At 298.2 K, it amounts to 1.374 mm2/s. Finally, the thermal conductivity along the [111] direction was calculated using the formula κ = λ × ρ × Cp where ρ = 5.53 g/cm3 is the crystal density measured using the buoyancy method. The thermal conductivity decreases with temperature, Fig. 5(c). At room temperature, it amounts to 4.33 Wm-1K-1, which is larger than for CNGG-type crystals [4,20]. The value of thermal conductivity for Tm:CLTGG is higher than that for undoped CTGG (3.76 Wm-1K-1) [14]. We refer this to the effect of Li+ codoping on eliminating the cationic vacancies and increasing the thermal conductivity. This effect seems to overcome the negative role of rare-earth doping which typically tends to decrease κ.

 figure: Fig. 5.

Fig. 5. Thermal properties of the Tm:CLTGG crystal as a function of temperature: (a) specific heat; (b) thermal diffusivity; (c) thermal conductivity.

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5. Optical spectroscopy

5.1 Optical absorption

The absorption spectrum was measured using a Varian CARY 5000 spectrophotometer. The cubic Tm:CLTGG is optically isotropic. The unpolarized RT absorption spectrum of Tm:CLTGG is shown in Fig. 6(a). In the spectrum, the well-resolved absorption bands are related to transitions of Tm3+ ions from the ground-state (3H6) to excited-states (from 3F4 to 1D2, in increasing energy order).

 figure: Fig. 6.

Fig. 6. Absorption of the Tm:CLTGG crystal: (a) RT absorption spectrum; (b) absorption cross-sections, σabs, for the 3H63H4 Tm3+ transition; (c) Tauc plot for the evaluation of the optical bandgap (Eg).

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The absorption cross-sections σabs for the 3H63H4 Tm3+ transition which is suitable for pumping of laser crystals by AlGaAs diode lasers emitting at ∼0.8 µm are shown in Fig. 6(b). The maximum σabs is 0.31×10−20 cm2 at 795.0 nm and the absorption bandwidth (full width at half maximum, FWHM) is 26.7 nm. Compared to the widespread Tm:Y3Al5O12 garnet crystal, Tm:CLTGG exhibits smoother and broader absorption at the expense of lower cross-section. This represents the effect of inhomogeneous broadening caused by the structural disorder and, in particular, the different cationic distributions around the Tm3+ ions, cf. Figure 3(b).

The absorption spectrum of Tm:CLTGG reveals no significant absorption in the visible from color centers related to cationic vacancies. This indicates charge compensation via Li+ doping. Figure 6(c) shows the Tauc plot for the determination of the UV absorption edge (assuming indirect transitions). The optical bandgap energy Eg is 4.88 eV (0.254 µm). At the onset of the host absorption, weak absorption bands due to transitions of Tm3+ ions to higher-lying 1I6 and 3P0-2 states are found.

5.2 Judd-Ofelt analysis

The transition intensities for Tm3+ ions were calculated from the absorption spectrum using the standard Judd-Ofelt (J-O) theory [17,18], and its modification accounting for configuration interaction (mJ-O theory) [19]. This formalism was used to determine the contributions of electric dipoles (ED). The magnetic dipole (MD) contributions for transitions with ΔJ = J – J’ = 0, ±1 were calculated independently within the approximation of Russell–Saunders on the wave functions of Tm3+ under an assumption of a free-ion. The refractive index of CLTGG was taken from [20].

The detailed procedure of the J-O calculations for Tm3+-doped crystals is described in detail elsewhere [21]. Here, we only discuss the main approximations. For the standard J-O theory, the ED line strengths of the J → J’ transition are given by:

$$S_{\textrm{calc}}^{\textrm{ED}}(JJ^{\prime}) = \sum\limits_{\textrm{k} = 2,4,6} {{U^{(\textrm{k})}}{\Omega _\textrm{k}}} ,$$
$${U^{(\textrm{k})}} = {\langle (4{\textrm{f}^\textrm{n}})SLJ||{U^\textrm{k}}||(4{\textrm{f}^\textrm{n}})S^{\prime}L^{\prime}J^{\prime}\rangle ^2}. $$

Here, U(k) are the reduced squared matrix elements which were calculated using the free-ion parameters from [22] and Ωk are the intensity (J–O) parameters (for both, k = 2, 4, 6).

In the mJ-O theory, it is assumed that only the excited configuration of opposite parity 4fn-15d1 contributes to the configuration interaction. The ED line strengths are then [19]:

$$S_{\textrm{calc}}^{\textrm{ED}}(JJ^{\prime}) = \sum\limits_{\textrm{k} = 2,4,6} {{U^{(\textrm{k})}}{{\tilde{\Omega }}_\textrm{k}}}, $$
$${\tilde{\Omega }_\textrm{k}} = {\Omega _\textrm{k}}[1 + 2\alpha ({E_J} + {E_{J^{\prime}}} - 2E_\textrm{f}^0)].$$

In other words, the intensity parameters ${\tilde{\Omega }_\textrm{k}}$ are linear functions of energies (EJ and EJ’) of the two multiplets, where Ef° is the mean energy of the 4fn configuration and α ≈ 1/(2Δ) where Δ ≈ E(4fn-15d1) – E(4fn) is the average energy difference between the fundamental and first excited configurations.

Table 2 summarizes the experimental and calculated absorption oscillator strengths f (the latter are determined by both the J-O and mJ-O theories from the corresponding line strengths). The intensity parameters are Ω2 = 1.715, Ω4 = 0.943 and Ω6 = 0.963 [10−20 cm2] (J-O theory) and Ω2 = 5.185, Ω4 = 0.650, Ω6 = 1.068 [10−20 cm2] and α = 0.171 [10−4 cm] (mJ-O theory). The latter theory provides lower root mean square (rms) deviation between the experimental and calculated f values, so that it was selected for further analysis.

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Table 2. Measured and Calculated Absorption Oscillator Strengths of Tm3+ ions in CLTGG crystala

The probabilities of spontaneous radiative transitions Acalc(JJ’), the luminescence branching ratios B(JJ’) and the radiative lifetimes of the excited-states τrad were calculated using the mJ-O theory, the results are shown in Table 3. For the 3F4 and 3H4 states, τrad is 5.33 ms and 0.55 ms, respectively.

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Table 3. Calculated Probabilities of Spontaneous Radiative Transitions of Tm3+ ions in CLTGG crystal (Obtained from the mJ-O Theory)a

5.3 Luminescence (emission spectra and lifetime)

The RT luminescence spectrum was measured using an optical spectrum analyzer (AQ6375B, Yokogawa) for which the spectral response was calibrated using a 20 W quartz iodine lamp. The pump source was a 795 nm Ti:Sapphire laser (excitation to the 3H4 state). The luminescence spectrum is shown in Fig. 7(a). The broad and intense band at 1.6 - 2.3 µm is due to the 3F43H6 transition, while the weaker band at 1.35 - 1.55 µm originates from the 3H43F4 transition.

 figure: Fig. 7.

Fig. 7. Near-infrared emission properties of the Tm:CLTGG crystal: (a) luminescence spectrum, λexc = 795 nm; (b,c) luminescence decay curves from the (b) 3F4 and (c) 3H4 Tm3+ states.

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The luminescence decay was studied at RT using an optical parametric oscillator (Horizon, Continuum), a 1/4 m monochomator (Oriel 77200), an InGaAs detector and an 8 GHz digital oscilloscope (DSA70804B, Tektronix). The sample was finely powdered to avoid the effect of radiation trapping. The decay curve from the 3F4 state is well fitted using a single-exponential law yielding a luminescence lifetime τlum of 4.93 ms (for the powdered sample), Fig. 7(b). It is only slightly shorter than the radiative one, revealing a relatively high quantum yield ηq = τlum/τrad = 92%. For the bulk sample, τlum = 6.50 ms due to the strong reabsorption. The decay from the 3H4 state is not single-exponential revealing the effect of cross-relaxation for neighboring Tm3+ ions. The mean decay time <τlum> = 0.159 ms, Fig. 7(c).

5.4 Low-temperature spectroscopy

The low temperature (LT, 10 K) absorption and luminescence spectra were measured using a cryostat (Oxford Instruments, model SU 12) with helium-gas close-cycle flow. In CLTGG, Tm3+ ions replace for the Ca2+ ones in dodecahedral sites with D2 symmetry. These sites are distorted due to the presence of univalent Li+ cations serving for charge compensation and various cation coordinations around the {A} sites, cf. Figure 3. Each 2S+1LJ multiplet with integer J is thus split into 2J + 1 Stark sub-levels. For brevity, in Fig. 8, we only show the absorption and luminescence spectra revealing the splitting of the 3F4 and 3H6 states relevant for ∼2 µm laser operation. The assignment of electronic transitions is after the work of Lupei et al. for ordered Tm3+-doped Gd3Ga5O12 (GGG) garnet [23]. Figure 8 reveals a significant inhomogeneous broadening of the absorption and luminescence bands of Tm3+ ions even at 10 K when the electron-phonon interaction is suppressed, which is a fingerprint of the structure disorder.

 figure: Fig. 8.

Fig. 8. Low-temperature (LT, 10 K) absorption and emission spectra for Tm3+ ions in the CLTGG crystal: (a) absorption, 3H63F4 transition; (b) emission, 3F43H6 and 3H43H6 transitions. The symbol “+” marks the assigned electronic transitions. Vertical dashes – crystal-field splitting in Tm:GGG after [23].

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The experimental energy-levels of Tm3+ ions in CLTGG are listed in Table 4 for the multiplets from 3H6 to 1D2. For the 3F43H6 transition of interest for ∼2 µm laser operation, the zero-phonon line (ZPL), i.e., the transition between the lowest Stark sub-levels of both multiplets, occurs at 1806nm (EZPL = 5538 cm-1). The partition functions for the ground-state and the excited-state, calculated at RT, amount to Z1 = 4.786 and Z2 = 2.402, respectively, so that their ratio Z1/Z2 = 1.992.

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Table 4. Experimental Energy Levels of Tm3+ ions in CLTGG crystal

5.5 Transition cross-sections

The absorption cross-section spectrum for the 3H63F4 transition is shown in Fig. 9(a), the maximum σabs reaches 0.25×10−20 cm2 at 1699 nm.

 figure: Fig. 9.

Fig. 9. 3H63F4 transition of Tm3+ ions in CLTGG: (a) absorption, σabs, and stimulated emission (SE), σSE, cross-sections; (b) gain cross-sections, σgain = σSE – (1 – β)σabs, where β = N2(3F4)/NTm is the inversion ratio.

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For the 3F43H6 transition, the stimulated-emission (SE) cross-section, σSE, spectra were calculated by two methods: the Füchtbauer–Ladenburg (F-L) equation [24] and the reciprocity method (RM) [25]. For the F-L equation, the luminescence spectrum was used, cf. Figure 7(a), the radiative lifetime of the 3F4 state was determined from the mJ-O theory (τrad = 5.33 ms) and the refractive index of the crystal (n ≈ 1.92) was taken from [20]. For the RM, we used the measured absorption spectrum and the determined crystal-field splitting, cf. Table 4. The results of both methods are shown in Fig. 9(a). They are in good agreement with each other. The maximum σSE reaches 0.35×10−20 cm2 at 1866nm and at longer wavelengths where laser operation is expected, σSE reaches 0.18×10−20 cm2 at 1992nm (both values correspond to the F-L method).

The ∼2 µm Tm laser represents a quasi-three-level scheme with reabsorption. Thus, gain cross-sections are usually calculated, σgain = σSE – (1 – β)σabs, where β = N2(3F4)/NTm is the inversion ratio. They are useful to conclude about the possible laser wavelength (in the free-running regime), the potential tuning range as well as the gain bandwidth in ML lasers. The gain spectra for Tm:CLTGG are shown in Fig. 9(b). The gain profiles of this disordered crystal are smooth and broad. For small and moderate inversion ratios (β < 0.16), a single local peak is observed in the spectra centered at ∼1.99 µm. The gain bandwidth (FWHM) for an intermediate β = 0.12 is as broad as 130 nm. The gain profiles extend well beyond 2 µm owing to the large total ground-state splitting (ΔE(3H6) = 668 cm-1) for Tm3+ ions and strong electron-phonon (vibronic) interaction with phonons of the host matrix. The longest purely electronic transition (neglecting the inhomogeneous broadening) for Tm3+ ions is 2053 nm.

6. Diode-pumped laser operation

6.1 Laser set-up

Figure 10(a) shows the scheme of the compact diode-pumped Tm:CLTGG laser. The laser element was cut along the [111] direction. It had an aperture of 3.05×3.09 mm2 and a thickness of 8.19 mm. Both end faces of the element were polished to laser quality and left uncoated. To remove the heat released during pumping, the element was wrapped in indium foil and fixed in a Cu-holder cooled by circulating water; the water temperature was 12 °C.

 figure: Fig. 10.

Fig. 10. (a) Scheme of the diode-pumped compact Tm:CLTGG laser: LD – laser diode, PM – pump mirror, OC – output coupler, F – cut-on filter; (b) far-field output profile of the laser mode, TOC = 5%, Pabs = 4.0 W.

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The laser cavity consisted of a flat pump mirror (PM) coated for high transmission (HT) at 0.80 µm and high reflection (HR) at 1.8-2.1 µm and a set of flat output couplers (OCs) having transmissions TOC of 1.5%, 3%, 5% or 9% at the laser wavelength. Both mirrors were placed close to the crystal resulting in a geometrical cavity length of ∼8.5 mm. The pump source comprised a fiber-coupled (fiber core diameter: 200 µm, N.A. = 0.22) AlGaAs diode laser emitting unpolarized output at a central wavelength of 793 nm (emission bandwidth: 5 nm, M2 > 80). The pump beam was collimated and focused into the laser element by an AR-coated lens assembly (reimaging ratio: 1:1, f = 30 mm). The pump spot size in the focus 2wP was 200 µm. The measured pump absorption was ∼47%. The residual pump was filtered out using a long pass filter (FEL1000, Thorlabs). The spectra of the laser output were measured using a spectrometer (WaveScan, APE). The profile of the laser mode in the far-field was captured using a FIND-R-SCOPE near-IR camera (model 85726).

6.2 Laser performance

The input-output dependences of the diode-pumped Tm:CLTGG laser are shown in Fig. 11(a). The laser generated a maximum output power of 1.08 W at 1995 and 2003 nm with a slope efficiency η of 23.8% (with respect to the absorbed pump power) and a laser threshold of 0.91 W (for TOC = 5%). At the maximum incident pump power of 11.7 W, the optical-to-optical conversion efficiency ηopt amounted to 9.2%. Further power scaling was limited by the thermal roll-over in the output dependences. With increasing the output coupling, the laser threshold increased from 0.68 W (TOC = 1.5%) to 1.46 W (TOC = 9%).

 figure: Fig. 11.

Fig. 11. Diode-pumped Tm:CLTGG laser: (a) input-output dependences, η – slope efficiency; (b) typical spectra of unpolarized laser emission measured at maximum Pabs.

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The laser generated unpolarized emission. The typical spectra of the laser emission are shown in Fig. 11(b). With increasing TOC from 1.5% to 9%, a blue shift of the emission wavelength was observed from 2012 and 2017nm to 1994 and 2002nm. This shift is due to the decreasing reabsorption losses in the crystal typical for quasi-three-level Tm lasers. It also agrees with the gain spectra of Tm:CLTGG, cf. Figure 9(b). The dual-wavelength emission was due to the etalon effect at the crystal / mirror interface and the broad and smooth gain profile.

The laser mode in the far-field, Fig. 10(b), was nearly circular.

A summary of output characteristics of CW lasers based on Tm3+-doped disordered gallium garnets is presented in Table 5.

Tables Icon

Table 5. Laser Performancesa of Tm3+-doped Gallium Garnets

7. Conclusions

To conclude, Tm:CLTGG is a promising crystal for ultrashort pulse generation (sub-100 fs) in the eye-safe spectral range of ∼2 µm. It exhibits a structural disorder related to a random site distribution of Ta5+, Ga3+ and Li+ cations over the same lattice sites, octahedral (16a) and tetrahedral (24d), which leads to a significant inhomogeneous broadening of the absorption and emission bands of Tm3+ ions confirmed at low temperature (10 K). At room temperature, due to a combination of the inhomogeneous broadening and electron-phonon interaction, Tm:CLTGG exhibits smooth and very broad gain profiles owing to the phonon-assisted 3F43H6 transition extending up to at least ∼2.2 µm. From X-ray diffraction, Raman spectroscopy and optical transmission, it is evident that Li+ ions provide charge compensation during the heterovalent doping (as Tm3+ ions are replacing Ca2+ ones) and almost eliminate the presence of cationic vacancies. Finally, Tm:CLTGG exhibits attractive thermal properties (for a disordered crystal) being superior to those of the CNGG-type crystals.

Funding

Ministerio de Ciencia, Innovación y Universidades (PID2019-108543RB-I00); Agència de Gestió d'Ajuts Universitaris i de Recerca (2017SGR755); National Natural Science Foundation of China (52072351); Foundation of President of China Academy of Engineering Physics (YZJJLX2018005); Key Laboratory of Optoelectronic Chemical Materials and Devices (2008DP173016); State Key Laboratory of Crystal Materials. Shandong University (KF2001); Departament d'Empresa i Coneixement, Generalitat de Catalunya (2020 FI-B 00522).

Disclosures

The authors declare no conflicts of interest.

Data Availability

Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.

References

1. J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011). [CrossRef]  

2. . Lupei, V. Lupei, L. Gheorghe, L. Rogobete, E. Osiac, and A. Petraru, “The nature of nonequivalent Nd3+ centers in CNGG and CLNGG,” Opt. Mater. 16(3), 403–411 (2001). [CrossRef]  

3. W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017). [CrossRef]  

4. Yu. K. Voronko, A. A. Sobol, A. Y. Karasik, N. A. Eskov, P. A. Rabochkina, and S. N. Ushakov, “Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions – effective laser media,” Opt. Mater. 20(3), 197–209 (2002). [CrossRef]  

5. E. Castellano-Hernández, M. D. Serrano, R. J. Jiménez Riobóo, C. Cascales, C. Zaldo, A. Jezowski, and P. A. Loiko, “Na modification of lanthanide doped Ca3Nb1.5Ga3.5O12-type laser garnets: Czochralski crystal growth and characterization,” Cryst. Growth Des. 16(3), 1480–1491 (2016). [CrossRef]  

6. Yu. K. Voron’ko, A. B. Kudryavtsev, N. A. Es’kov, V. V. Osiko, A. A. Sobol’, E. V. Sorokin, and F. M. Spiridonov, “Raman scattering of light in crystals and melt of calcium-niobium gallium garnet,” Sov. Phys. Dokl. 32(1), 70–73 (1988).

7. M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017). [CrossRef]  

8. Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018). [CrossRef]  

9. J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021). [CrossRef]  

10. Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018). [CrossRef]  

11. Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018). [CrossRef]  

12. Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021). [CrossRef]  

13. Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019). [CrossRef]  

14. C. Ma, Y. Wang, X. Cheng, M. Xue, C. Zuo, C. Gao, S. Guo, and J. He, “Spectroscopic, thermal, and laser properties of disordered garnet Nd:CLTGG crystal,” J. Cryst. Growth 504, 44–50 (2018). [CrossRef]  

15. G. Q. Xie, D. Y. Tang, W. D. Tan, H. Luo, S. Y. Guo, H. H. Yu, and H. J. Zhang, “Diode-pumped passively mode-locked Nd:CTGG disordered crystal laser,” Appl. Phys. B 95(4), 691–695 (2009). [CrossRef]  

16. F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014). [CrossRef]  

17. B. R. Judd, “Optical absorption intensities of rare-earth ions,” Phys. Rev. 127(3), 750–761 (1962). [CrossRef]  

18. G. S. Ofelt, “Intensities of crystal spectra of rare-earth ions,” J. Chem. Phys. 37(3), 511–520 (1962). [CrossRef]  

19. P. Loiko, A. Volokitina, X. Mateos, E. Dunina, A. Kornienko, E. Vilejshikova, M. Aguilo, and F. Diaz, “Spectroscopy of Tb3+ ions in monoclinic KLu(WO4)2 crystal: application of an intermediate configuration interaction theory,” Opt. Mater. 78, 495–501 (2018). [CrossRef]  

20. S. Guo, D. Yuan, X. Zhang, X. Cheng, F. Yu, and X. Tao, “Growth and characterizations of calcium tantalum gallium garnet single crystal,” J. Cryst. Growth 311(1), 214–217 (2008). [CrossRef]  

21. B. M. Walsh, N. P. Barnes, and B. Di Bartolo, “Branching ratios, cross sections, and radiative lifetimes of rare earth ions in solids: Application to Tm3+ and Ho3+ ions in LiYF4,” J. Appl. Phys. 83(5), 2772–2787 (1998). [CrossRef]  

22. P. S. Peijzel, P. Vergeer, A. Meijerink, M. F. Reid, L. A. Boatner, and G. W. Burdick, “4fn−15d→4fn emission of Ce3+, Pr3+, Nd3+, Er3+, and Tm3+ in LiYF4 and YPO4,” Phys. Rev. B 71(4), 045116 (2005). [CrossRef]  

23. V. Lupei, S. Lupei, C. Grecu, G. Tiseanu, and Boulon, “Crystal-field levels of Tm3+ in gadolinium gallium garnet,” J. Appl. Phys. 75(9), 4652–4657 (1994). [CrossRef]  

24. H. Aull and Jenssen, “Vibronic interactions in Nd:YAG resulting in nonreciprocity of absorption and stimulated emission cross sections,” IEEE J. Quantum Electron. 18(5), 925–930 (1982). [CrossRef]  

25. S. A. Payne, L. L. Chase, L. K. Smith, W. L. Kway, and W. F. Krupke, “Infrared cross-section measurements for crystals doped with Er3+, Tm3+, and Ho3+,” IEEE J. Quantum Electron. 28(11), 2619–2630 (1992). [CrossRef]  

26. W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013). [CrossRef]  

27. Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019). [CrossRef]  

28. Y. K. Voronko, S. B. Gessen, N. A. Es’ kov, A. G. Okhrimchuk, D. V. Smolin, A. A. Sobol, S. N. Ushakov, L. I. Tsymbal, and A. V. Shestakov, “Continuous lasing at a 2 μm wavelength in calcium niobium gallium garnet crystals at room temperature,” Quantum Electron. 26(3), 222–223 (1996). [CrossRef]  

References

  • View by:

  1. J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011).
    [Crossref]
  2. . Lupei, V. Lupei, L. Gheorghe, L. Rogobete, E. Osiac, and A. Petraru, “The nature of nonequivalent Nd3+ centers in CNGG and CLNGG,” Opt. Mater. 16(3), 403–411 (2001).
    [Crossref]
  3. W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017).
    [Crossref]
  4. Yu. K. Voronko, A. A. Sobol, A. Y. Karasik, N. A. Eskov, P. A. Rabochkina, and S. N. Ushakov, “Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions – effective laser media,” Opt. Mater. 20(3), 197–209 (2002).
    [Crossref]
  5. E. Castellano-Hernández, M. D. Serrano, R. J. Jiménez Riobóo, C. Cascales, C. Zaldo, A. Jezowski, and P. A. Loiko, “Na modification of lanthanide doped Ca3Nb1.5Ga3.5O12-type laser garnets: Czochralski crystal growth and characterization,” Cryst. Growth Des. 16(3), 1480–1491 (2016).
    [Crossref]
  6. Yu. K. Voron’ko, A. B. Kudryavtsev, N. A. Es’kov, V. V. Osiko, A. A. Sobol’, E. V. Sorokin, and F. M. Spiridonov, “Raman scattering of light in crystals and melt of calcium-niobium gallium garnet,” Sov. Phys. Dokl. 32(1), 70–73 (1988).
  7. M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
    [Crossref]
  8. Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
    [Crossref]
  9. J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021).
    [Crossref]
  10. Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
    [Crossref]
  11. Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
    [Crossref]
  12. Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
    [Crossref]
  13. Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
    [Crossref]
  14. C. Ma, Y. Wang, X. Cheng, M. Xue, C. Zuo, C. Gao, S. Guo, and J. He, “Spectroscopic, thermal, and laser properties of disordered garnet Nd:CLTGG crystal,” J. Cryst. Growth 504, 44–50 (2018).
    [Crossref]
  15. G. Q. Xie, D. Y. Tang, W. D. Tan, H. Luo, S. Y. Guo, H. H. Yu, and H. J. Zhang, “Diode-pumped passively mode-locked Nd:CTGG disordered crystal laser,” Appl. Phys. B 95(4), 691–695 (2009).
    [Crossref]
  16. F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
    [Crossref]
  17. B. R. Judd, “Optical absorption intensities of rare-earth ions,” Phys. Rev. 127(3), 750–761 (1962).
    [Crossref]
  18. G. S. Ofelt, “Intensities of crystal spectra of rare-earth ions,” J. Chem. Phys. 37(3), 511–520 (1962).
    [Crossref]
  19. P. Loiko, A. Volokitina, X. Mateos, E. Dunina, A. Kornienko, E. Vilejshikova, M. Aguilo, and F. Diaz, “Spectroscopy of Tb3+ ions in monoclinic KLu(WO4)2 crystal: application of an intermediate configuration interaction theory,” Opt. Mater. 78, 495–501 (2018).
    [Crossref]
  20. S. Guo, D. Yuan, X. Zhang, X. Cheng, F. Yu, and X. Tao, “Growth and characterizations of calcium tantalum gallium garnet single crystal,” J. Cryst. Growth 311(1), 214–217 (2008).
    [Crossref]
  21. B. M. Walsh, N. P. Barnes, and B. Di Bartolo, “Branching ratios, cross sections, and radiative lifetimes of rare earth ions in solids: Application to Tm3+ and Ho3+ ions in LiYF4,” J. Appl. Phys. 83(5), 2772–2787 (1998).
    [Crossref]
  22. P. S. Peijzel, P. Vergeer, A. Meijerink, M. F. Reid, L. A. Boatner, and G. W. Burdick, “4fn−15d→4fn emission of Ce3+, Pr3+, Nd3+, Er3+, and Tm3+ in LiYF4 and YPO4,” Phys. Rev. B 71(4), 045116 (2005).
    [Crossref]
  23. V. Lupei, S. Lupei, C. Grecu, G. Tiseanu, and Boulon, “Crystal-field levels of Tm3+ in gadolinium gallium garnet,” J. Appl. Phys. 75(9), 4652–4657 (1994).
    [Crossref]
  24. H. Aull and Jenssen, “Vibronic interactions in Nd:YAG resulting in nonreciprocity of absorption and stimulated emission cross sections,” IEEE J. Quantum Electron. 18(5), 925–930 (1982).
    [Crossref]
  25. S. A. Payne, L. L. Chase, L. K. Smith, W. L. Kway, and W. F. Krupke, “Infrared cross-section measurements for crystals doped with Er3+, Tm3+, and Ho3+,” IEEE J. Quantum Electron. 28(11), 2619–2630 (1992).
    [Crossref]
  26. W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
    [Crossref]
  27. Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
    [Crossref]
  28. Y. K. Voronko, S. B. Gessen, N. A. Es’ kov, A. G. Okhrimchuk, D. V. Smolin, A. A. Sobol, S. N. Ushakov, L. I. Tsymbal, and A. V. Shestakov, “Continuous lasing at a 2 μm wavelength in calcium niobium gallium garnet crystals at room temperature,” Quantum Electron. 26(3), 222–223 (1996).
    [Crossref]

2021 (2)

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021).
[Crossref]

2019 (2)

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
[Crossref]

2018 (5)

2017 (2)

M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
[Crossref]

W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017).
[Crossref]

2016 (1)

E. Castellano-Hernández, M. D. Serrano, R. J. Jiménez Riobóo, C. Cascales, C. Zaldo, A. Jezowski, and P. A. Loiko, “Na modification of lanthanide doped Ca3Nb1.5Ga3.5O12-type laser garnets: Czochralski crystal growth and characterization,” Cryst. Growth Des. 16(3), 1480–1491 (2016).
[Crossref]

2014 (1)

F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
[Crossref]

2013 (1)

W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
[Crossref]

2011 (1)

J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011).
[Crossref]

2009 (1)

G. Q. Xie, D. Y. Tang, W. D. Tan, H. Luo, S. Y. Guo, H. H. Yu, and H. J. Zhang, “Diode-pumped passively mode-locked Nd:CTGG disordered crystal laser,” Appl. Phys. B 95(4), 691–695 (2009).
[Crossref]

2008 (1)

S. Guo, D. Yuan, X. Zhang, X. Cheng, F. Yu, and X. Tao, “Growth and characterizations of calcium tantalum gallium garnet single crystal,” J. Cryst. Growth 311(1), 214–217 (2008).
[Crossref]

2005 (1)

P. S. Peijzel, P. Vergeer, A. Meijerink, M. F. Reid, L. A. Boatner, and G. W. Burdick, “4fn−15d→4fn emission of Ce3+, Pr3+, Nd3+, Er3+, and Tm3+ in LiYF4 and YPO4,” Phys. Rev. B 71(4), 045116 (2005).
[Crossref]

2002 (1)

Yu. K. Voronko, A. A. Sobol, A. Y. Karasik, N. A. Eskov, P. A. Rabochkina, and S. N. Ushakov, “Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions – effective laser media,” Opt. Mater. 20(3), 197–209 (2002).
[Crossref]

2001 (1)

. Lupei, V. Lupei, L. Gheorghe, L. Rogobete, E. Osiac, and A. Petraru, “The nature of nonequivalent Nd3+ centers in CNGG and CLNGG,” Opt. Mater. 16(3), 403–411 (2001).
[Crossref]

1998 (1)

B. M. Walsh, N. P. Barnes, and B. Di Bartolo, “Branching ratios, cross sections, and radiative lifetimes of rare earth ions in solids: Application to Tm3+ and Ho3+ ions in LiYF4,” J. Appl. Phys. 83(5), 2772–2787 (1998).
[Crossref]

1996 (1)

Y. K. Voronko, S. B. Gessen, N. A. Es’ kov, A. G. Okhrimchuk, D. V. Smolin, A. A. Sobol, S. N. Ushakov, L. I. Tsymbal, and A. V. Shestakov, “Continuous lasing at a 2 μm wavelength in calcium niobium gallium garnet crystals at room temperature,” Quantum Electron. 26(3), 222–223 (1996).
[Crossref]

1994 (1)

V. Lupei, S. Lupei, C. Grecu, G. Tiseanu, and Boulon, “Crystal-field levels of Tm3+ in gadolinium gallium garnet,” J. Appl. Phys. 75(9), 4652–4657 (1994).
[Crossref]

1992 (1)

S. A. Payne, L. L. Chase, L. K. Smith, W. L. Kway, and W. F. Krupke, “Infrared cross-section measurements for crystals doped with Er3+, Tm3+, and Ho3+,” IEEE J. Quantum Electron. 28(11), 2619–2630 (1992).
[Crossref]

1988 (1)

Yu. K. Voron’ko, A. B. Kudryavtsev, N. A. Es’kov, V. V. Osiko, A. A. Sobol’, E. V. Sorokin, and F. M. Spiridonov, “Raman scattering of light in crystals and melt of calcium-niobium gallium garnet,” Sov. Phys. Dokl. 32(1), 70–73 (1988).

1982 (1)

H. Aull and Jenssen, “Vibronic interactions in Nd:YAG resulting in nonreciprocity of absorption and stimulated emission cross sections,” IEEE J. Quantum Electron. 18(5), 925–930 (1982).
[Crossref]

1962 (2)

B. R. Judd, “Optical absorption intensities of rare-earth ions,” Phys. Rev. 127(3), 750–761 (1962).
[Crossref]

G. S. Ofelt, “Intensities of crystal spectra of rare-earth ions,” J. Chem. Phys. 37(3), 511–520 (1962).
[Crossref]

Aguilo, M.

P. Loiko, A. Volokitina, X. Mateos, E. Dunina, A. Kornienko, E. Vilejshikova, M. Aguilo, and F. Diaz, “Spectroscopy of Tb3+ ions in monoclinic KLu(WO4)2 crystal: application of an intermediate configuration interaction theory,” Opt. Mater. 78, 495–501 (2018).
[Crossref]

Aguiló, M.

Alonso, J. A.

M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
[Crossref]

Álvarez-Pérez, J. O.

J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021).
[Crossref]

M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
[Crossref]

Aull, H.

H. Aull and Jenssen, “Vibronic interactions in Nd:YAG resulting in nonreciprocity of absorption and stimulated emission cross sections,” IEEE J. Quantum Electron. 18(5), 925–930 (1982).
[Crossref]

Bae, J. E.

Barnes, N. P.

B. M. Walsh, N. P. Barnes, and B. Di Bartolo, “Branching ratios, cross sections, and radiative lifetimes of rare earth ions in solids: Application to Tm3+ and Ho3+ ions in LiYF4,” J. Appl. Phys. 83(5), 2772–2787 (1998).
[Crossref]

Boatner, L. A.

P. S. Peijzel, P. Vergeer, A. Meijerink, M. F. Reid, L. A. Boatner, and G. W. Burdick, “4fn−15d→4fn emission of Ce3+, Pr3+, Nd3+, Er3+, and Tm3+ in LiYF4 and YPO4,” Phys. Rev. B 71(4), 045116 (2005).
[Crossref]

Boulon,

V. Lupei, S. Lupei, C. Grecu, G. Tiseanu, and Boulon, “Crystal-field levels of Tm3+ in gadolinium gallium garnet,” J. Appl. Phys. 75(9), 4652–4657 (1994).
[Crossref]

Burdick, G. W.

P. S. Peijzel, P. Vergeer, A. Meijerink, M. F. Reid, L. A. Boatner, and G. W. Burdick, “4fn−15d→4fn emission of Ce3+, Pr3+, Nd3+, Er3+, and Tm3+ in LiYF4 and YPO4,” Phys. Rev. B 71(4), 045116 (2005).
[Crossref]

Cai, H.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
[Crossref]

Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
[Crossref]

Camy, P.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Cano-Torres, J. M.

J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021).
[Crossref]

J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011).
[Crossref]

Cascales, C.

J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021).
[Crossref]

M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
[Crossref]

E. Castellano-Hernández, M. D. Serrano, R. J. Jiménez Riobóo, C. Cascales, C. Zaldo, A. Jezowski, and P. A. Loiko, “Na modification of lanthanide doped Ca3Nb1.5Ga3.5O12-type laser garnets: Czochralski crystal growth and characterization,” Cryst. Growth Des. 16(3), 1480–1491 (2016).
[Crossref]

J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011).
[Crossref]

Castellano-Hernández, E.

E. Castellano-Hernández, M. D. Serrano, R. J. Jiménez Riobóo, C. Cascales, C. Zaldo, A. Jezowski, and P. A. Loiko, “Na modification of lanthanide doped Ca3Nb1.5Ga3.5O12-type laser garnets: Czochralski crystal growth and characterization,” Cryst. Growth Des. 16(3), 1480–1491 (2016).
[Crossref]

Chase, L. L.

S. A. Payne, L. L. Chase, L. K. Smith, W. L. Kway, and W. F. Krupke, “Infrared cross-section measurements for crystals doped with Er3+, Tm3+, and Ho3+,” IEEE J. Quantum Electron. 28(11), 2619–2630 (1992).
[Crossref]

Chen, W.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Cheng, X.

C. Ma, Y. Wang, X. Cheng, M. Xue, C. Zuo, C. Gao, S. Guo, and J. He, “Spectroscopic, thermal, and laser properties of disordered garnet Nd:CLTGG crystal,” J. Cryst. Growth 504, 44–50 (2018).
[Crossref]

S. Guo, D. Yuan, X. Zhang, X. Cheng, F. Yu, and X. Tao, “Growth and characterizations of calcium tantalum gallium garnet single crystal,” J. Cryst. Growth 311(1), 214–217 (2008).
[Crossref]

Choi, S. Y.

Dai, X.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
[Crossref]

Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
[Crossref]

Di Bartolo, B.

B. M. Walsh, N. P. Barnes, and B. Di Bartolo, “Branching ratios, cross sections, and radiative lifetimes of rare earth ions in solids: Application to Tm3+ and Ho3+ ions in LiYF4,” J. Appl. Phys. 83(5), 2772–2787 (1998).
[Crossref]

Diaz, F.

P. Loiko, A. Volokitina, X. Mateos, E. Dunina, A. Kornienko, E. Vilejshikova, M. Aguilo, and F. Diaz, “Spectroscopy of Tb3+ ions in monoclinic KLu(WO4)2 crystal: application of an intermediate configuration interaction theory,” Opt. Mater. 78, 495–501 (2018).
[Crossref]

Díaz, F.

Doualan, J. L.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Dunina, E.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

P. Loiko, A. Volokitina, X. Mateos, E. Dunina, A. Kornienko, E. Vilejshikova, M. Aguilo, and F. Diaz, “Spectroscopy of Tb3+ ions in monoclinic KLu(WO4)2 crystal: application of an intermediate configuration interaction theory,” Opt. Mater. 78, 495–501 (2018).
[Crossref]

Es’ kov, N. A.

Y. K. Voronko, S. B. Gessen, N. A. Es’ kov, A. G. Okhrimchuk, D. V. Smolin, A. A. Sobol, S. N. Ushakov, L. I. Tsymbal, and A. V. Shestakov, “Continuous lasing at a 2 μm wavelength in calcium niobium gallium garnet crystals at room temperature,” Quantum Electron. 26(3), 222–223 (1996).
[Crossref]

Es’kov, N. A.

Yu. K. Voron’ko, A. B. Kudryavtsev, N. A. Es’kov, V. V. Osiko, A. A. Sobol’, E. V. Sorokin, and F. M. Spiridonov, “Raman scattering of light in crystals and melt of calcium-niobium gallium garnet,” Sov. Phys. Dokl. 32(1), 70–73 (1988).

Eskov, N. A.

Yu. K. Voronko, A. A. Sobol, A. Y. Karasik, N. A. Eskov, P. A. Rabochkina, and S. N. Ushakov, “Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions – effective laser media,” Opt. Mater. 20(3), 197–209 (2002).
[Crossref]

Fernández Díaz, M. T.

M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
[Crossref]

Fomicheva, L.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Gao, C.

C. Ma, Y. Wang, X. Cheng, M. Xue, C. Zuo, C. Gao, S. Guo, and J. He, “Spectroscopic, thermal, and laser properties of disordered garnet Nd:CLTGG crystal,” J. Cryst. Growth 504, 44–50 (2018).
[Crossref]

Gao, W. L.

W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
[Crossref]

Gessen, S. B.

Y. K. Voronko, S. B. Gessen, N. A. Es’ kov, A. G. Okhrimchuk, D. V. Smolin, A. A. Sobol, S. N. Ushakov, L. I. Tsymbal, and A. V. Shestakov, “Continuous lasing at a 2 μm wavelength in calcium niobium gallium garnet crystals at room temperature,” Quantum Electron. 26(3), 222–223 (1996).
[Crossref]

Gheorghe, L.

. Lupei, V. Lupei, L. Gheorghe, L. Rogobete, E. Osiac, and A. Petraru, “The nature of nonequivalent Nd3+ centers in CNGG and CLNGG,” Opt. Mater. 16(3), 403–411 (2001).
[Crossref]

Grecu, C.

V. Lupei, S. Lupei, C. Grecu, G. Tiseanu, and Boulon, “Crystal-field levels of Tm3+ in gadolinium gallium garnet,” J. Appl. Phys. 75(9), 4652–4657 (1994).
[Crossref]

Griebner, U.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
[Crossref]

Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
[Crossref]

W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017).
[Crossref]

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Kränkel, C.

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S. A. Payne, L. L. Chase, L. K. Smith, W. L. Kway, and W. F. Krupke, “Infrared cross-section measurements for crystals doped with Er3+, Tm3+, and Ho3+,” IEEE J. Quantum Electron. 28(11), 2619–2630 (1992).
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Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
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Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
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W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
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F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
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Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
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Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
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Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
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P. Loiko, A. Volokitina, X. Mateos, E. Dunina, A. Kornienko, E. Vilejshikova, M. Aguilo, and F. Diaz, “Spectroscopy of Tb3+ ions in monoclinic KLu(WO4)2 crystal: application of an intermediate configuration interaction theory,” Opt. Mater. 78, 495–501 (2018).
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W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017).
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E. Castellano-Hernández, M. D. Serrano, R. J. Jiménez Riobóo, C. Cascales, C. Zaldo, A. Jezowski, and P. A. Loiko, “Na modification of lanthanide doped Ca3Nb1.5Ga3.5O12-type laser garnets: Czochralski crystal growth and characterization,” Cryst. Growth Des. 16(3), 1480–1491 (2016).
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W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
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Mateos, X.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
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P. Loiko, A. Volokitina, X. Mateos, E. Dunina, A. Kornienko, E. Vilejshikova, M. Aguilo, and F. Diaz, “Spectroscopy of Tb3+ ions in monoclinic KLu(WO4)2 crystal: application of an intermediate configuration interaction theory,” Opt. Mater. 78, 495–501 (2018).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
[Crossref]

Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
[Crossref]

W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017).
[Crossref]

J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011).
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. Lupei, V. Lupei, L. Gheorghe, L. Rogobete, E. Osiac, and A. Petraru, “The nature of nonequivalent Nd3+ centers in CNGG and CLNGG,” Opt. Mater. 16(3), 403–411 (2001).
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Pan, Z.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
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Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
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Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
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S. A. Payne, L. L. Chase, L. K. Smith, W. L. Kway, and W. F. Krupke, “Infrared cross-section measurements for crystals doped with Er3+, Tm3+, and Ho3+,” IEEE J. Quantum Electron. 28(11), 2619–2630 (1992).
[Crossref]

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P. S. Peijzel, P. Vergeer, A. Meijerink, M. F. Reid, L. A. Boatner, and G. W. Burdick, “4fn−15d→4fn emission of Ce3+, Pr3+, Nd3+, Er3+, and Tm3+ in LiYF4 and YPO4,” Phys. Rev. B 71(4), 045116 (2005).
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Petraru, A.

. Lupei, V. Lupei, L. Gheorghe, L. Rogobete, E. Osiac, and A. Petraru, “The nature of nonequivalent Nd3+ centers in CNGG and CLNGG,” Opt. Mater. 16(3), 403–411 (2001).
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Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
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Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
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W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017).
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J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011).
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Qin, Z.

Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
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Rabochkina, P. A.

Yu. K. Voronko, A. A. Sobol, A. Y. Karasik, N. A. Eskov, P. A. Rabochkina, and S. N. Ushakov, “Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions – effective laser media,” Opt. Mater. 20(3), 197–209 (2002).
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P. S. Peijzel, P. Vergeer, A. Meijerink, M. F. Reid, L. A. Boatner, and G. W. Burdick, “4fn−15d→4fn emission of Ce3+, Pr3+, Nd3+, Er3+, and Tm3+ in LiYF4 and YPO4,” Phys. Rev. B 71(4), 045116 (2005).
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J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011).
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M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
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J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021).
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M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
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Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
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Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
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Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
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Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
[Crossref]

W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017).
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Yu. K. Voronko, A. A. Sobol, A. Y. Karasik, N. A. Eskov, P. A. Rabochkina, and S. N. Ushakov, “Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions – effective laser media,” Opt. Mater. 20(3), 197–209 (2002).
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M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
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Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
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Sotor, J.

Spiridonov, F. M.

Yu. K. Voron’ko, A. B. Kudryavtsev, N. A. Es’kov, V. V. Osiko, A. A. Sobol’, E. V. Sorokin, and F. M. Spiridonov, “Raman scattering of light in crystals and melt of calcium-niobium gallium garnet,” Sov. Phys. Dokl. 32(1), 70–73 (1988).

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Yu. K. Voronko, A. A. Sobol, A. Y. Karasik, N. A. Eskov, P. A. Rabochkina, and S. N. Ushakov, “Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions – effective laser media,” Opt. Mater. 20(3), 197–209 (2002).
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Y. K. Voronko, S. B. Gessen, N. A. Es’ kov, A. G. Okhrimchuk, D. V. Smolin, A. A. Sobol, S. N. Ushakov, L. I. Tsymbal, and A. V. Shestakov, “Continuous lasing at a 2 μm wavelength in calcium niobium gallium garnet crystals at room temperature,” Quantum Electron. 26(3), 222–223 (1996).
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P. Loiko, A. Volokitina, X. Mateos, E. Dunina, A. Kornienko, E. Vilejshikova, M. Aguilo, and F. Diaz, “Spectroscopy of Tb3+ ions in monoclinic KLu(WO4)2 crystal: application of an intermediate configuration interaction theory,” Opt. Mater. 78, 495–501 (2018).
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Yu. K. Voron’ko, A. B. Kudryavtsev, N. A. Es’kov, V. V. Osiko, A. A. Sobol’, E. V. Sorokin, and F. M. Spiridonov, “Raman scattering of light in crystals and melt of calcium-niobium gallium garnet,” Sov. Phys. Dokl. 32(1), 70–73 (1988).

Voronko, Y. K.

Y. K. Voronko, S. B. Gessen, N. A. Es’ kov, A. G. Okhrimchuk, D. V. Smolin, A. A. Sobol, S. N. Ushakov, L. I. Tsymbal, and A. V. Shestakov, “Continuous lasing at a 2 μm wavelength in calcium niobium gallium garnet crystals at room temperature,” Quantum Electron. 26(3), 222–223 (1996).
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Yu. K. Voronko, A. A. Sobol, A. Y. Karasik, N. A. Eskov, P. A. Rabochkina, and S. N. Ushakov, “Calcium niobium gallium and calcium lithium niobium gallium garnets doped with rare earth ions – effective laser media,” Opt. Mater. 20(3), 197–209 (2002).
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Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
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Wang, J. Y.

W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
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Wang, L.

Wang, Q.

Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
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F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
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Wang, Y.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
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Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
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C. Ma, Y. Wang, X. Cheng, M. Xue, C. Zuo, C. Gao, S. Guo, and J. He, “Spectroscopic, thermal, and laser properties of disordered garnet Nd:CLTGG crystal,” J. Cryst. Growth 504, 44–50 (2018).
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W. Jing, P. Loiko, J. M. Serres, Y. Wang, E. Vilejshikova, M. Aguiló, F. Díaz, U. Griebner, H. Huang, V. Petrov, and X. Mateos, “Synthesis, spectroscopy, and efficient laser operation of “mixed” sesquioxide Tm:(Lu, Sc)2O3 transparent ceramics,” Opt. Mater. Express 7(11), 4192–4202 (2017).
[Crossref]

Wang, Z. W.

F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
[Crossref]

Xie, G.

Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
[Crossref]

Xie, G. Q.

W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
[Crossref]

G. Q. Xie, D. Y. Tang, W. D. Tan, H. Luo, S. Y. Guo, H. H. Yu, and H. J. Zhang, “Diode-pumped passively mode-locked Nd:CTGG disordered crystal laser,” Appl. Phys. B 95(4), 691–695 (2009).
[Crossref]

Xu, X.

Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
[Crossref]

Xue, M.

C. Ma, Y. Wang, X. Cheng, M. Xue, C. Zuo, C. Gao, S. Guo, and J. He, “Spectroscopic, thermal, and laser properties of disordered garnet Nd:CLTGG crystal,” J. Cryst. Growth 504, 44–50 (2018).
[Crossref]

Xue, Y.

Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
[Crossref]

Yang, K. J.

F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
[Crossref]

Yu, F.

S. Guo, D. Yuan, X. Zhang, X. Cheng, F. Yu, and X. Tao, “Growth and characterizations of calcium tantalum gallium garnet single crystal,” J. Cryst. Growth 311(1), 214–217 (2008).
[Crossref]

Yu, H. H.

W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
[Crossref]

G. Q. Xie, D. Y. Tang, W. D. Tan, H. Luo, S. Y. Guo, H. H. Yu, and H. J. Zhang, “Diode-pumped passively mode-locked Nd:CTGG disordered crystal laser,” Appl. Phys. B 95(4), 691–695 (2009).
[Crossref]

Yuan, D.

S. Guo, D. Yuan, X. Zhang, X. Cheng, F. Yu, and X. Tao, “Growth and characterizations of calcium tantalum gallium garnet single crystal,” J. Cryst. Growth 311(1), 214–217 (2008).
[Crossref]

Yuan, H.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
[Crossref]

Yuan, P.

W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
[Crossref]

Zaldo, C.

J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021).
[Crossref]

M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
[Crossref]

E. Castellano-Hernández, M. D. Serrano, R. J. Jiménez Riobóo, C. Cascales, C. Zaldo, A. Jezowski, and P. A. Loiko, “Na modification of lanthanide doped Ca3Nb1.5Ga3.5O12-type laser garnets: Czochralski crystal growth and characterization,” Cryst. Growth Des. 16(3), 1480–1491 (2016).
[Crossref]

J. M. Cano-Torres, M. Rico, X. Han, M. D. Serrano, C. Cascales, C. Zaldo, V. Petrov, U. Griebner, X. Mateos, P. Koopmann, and C. Kränkel, “Comparative study of crystallographic, spectroscopic, and laser properties of Tm3+ in NaT(WO4)2 (T = La, Gd, Y, and Lu) disordered single crystals,” Phys. Rev. B 84(17), 174207 (2011).
[Crossref]

Zhang, B. T.

F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
[Crossref]

Zhang, H. J.

W. L. Gao, G. Q. Xie, J. Ma, M. N. Liu, P. Yuan, L. J. Qian, H. H. Yu, H. J. Zhang, and J. Y. Wang, “Efficient 2 μm Tm:CLNGG disordered crystal laser,” Opt. Mater. 35(4), 715–717 (2013).
[Crossref]

G. Q. Xie, D. Y. Tang, W. D. Tan, H. Luo, S. Y. Guo, H. H. Yu, and H. J. Zhang, “Diode-pumped passively mode-locked Nd:CTGG disordered crystal laser,” Appl. Phys. B 95(4), 691–695 (2009).
[Crossref]

Zhang, X.

S. Guo, D. Yuan, X. Zhang, X. Cheng, F. Yu, and X. Tao, “Growth and characterizations of calcium tantalum gallium garnet single crystal,” J. Cryst. Growth 311(1), 214–217 (2008).
[Crossref]

Zhang, X. T.

F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
[Crossref]

Zhang, Y.

Zhao, Y.

Z. Pan, P. Loiko, Y. Wang, Y. Zhao, H. Yuan, K. Tang, X. Dai, H. Cai, J. M. Serres, S. Slimi, E. B. Salem, E. Dunina, A. Kornienko, L. Fomicheva, J. L. Doualan, P. Camy, W. Chen, U. Griebner, V. Petrov, M. Aguiló, F. Díaz, R. M. Solé, and X. Mateos, “Disordered Tm3+, Ho3+-codoped CNGG garnet crystal: Towards efficient laser materials for ultrashort pulse generation at ∼2 μm,” J. Alloys Compd. 853, 157100 (2021).
[Crossref]

Y. Zhao, Y. Wang, W. Chen, Z. Pan, L. Wang, X. Dai, H. Yuan, Y. Zhang, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, W. Zhou, D. Shen, U. Griebner, and V. Petrov, “67-fs pulse generation from a mode-locked Tm,Ho:CLNGG laser at 2083nm,” Opt. Express 27(3), 1922–1928 (2019).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, M. Kowalczyk, J. Sotor, H. Yuan, Y. Zhang, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, P. Loiko, J. M. Serres, X. Mateos, U. Griebner, and V. Petrov, “Sub-80 fs mode-locked Tm,Ho-codoped disordered garnet crystal oscillator operating at 2081nm,” Opt. Lett. 43(20), 5154–5157 (2018).
[Crossref]

Z. Pan, Y. Wang, Y. Zhao, H. Yuan, X. Dai, H. Cai, J. E. Bae, S. Y. Choi, F. Rotermund, X. Mateos, J. Maria Serres, P. Loiko, U. Griebner, and V. Petrov, “Generation of 84-fs pulses from a mode-locked Tm:CNNGG disordered garnet crystal laser,” Photon. Res. 6(8), 800–804 (2018).
[Crossref]

Z. Pan, J. M. Serres, E. Kifle, P. Loiko, H. Yuan, X. Dai, H. Cai, M. Aguiló, F. Díaz, Y. Wang, Y. Zhao, U. Griebner, V. Petrov, and X. Mateos, “Comparative study of the spectroscopic and laser properties of Tm3+, Na+(Li+)-codoped Ca3Nb1.5Ga3.5O12-type disordered garnet crystals for mode-locked lasers,” Opt. Mater. Express 8(8), 2287–2299 (2018).
[Crossref]

Zhou, W.

Zuo, C.

C. Ma, Y. Wang, X. Cheng, M. Xue, C. Zuo, C. Gao, S. Guo, and J. He, “Spectroscopic, thermal, and laser properties of disordered garnet Nd:CLTGG crystal,” J. Cryst. Growth 504, 44–50 (2018).
[Crossref]

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G. Q. Xie, D. Y. Tang, W. D. Tan, H. Luo, S. Y. Guo, H. H. Yu, and H. J. Zhang, “Diode-pumped passively mode-locked Nd:CTGG disordered crystal laser,” Appl. Phys. B 95(4), 691–695 (2009).
[Crossref]

F. Lou, S. Y. Guo, J. L. He, B. T. Zhang, J. Hou, Z. W. Wang, X. T. Zhang, K. J. Yang, R. H. Wang, and X. M. Liu, “Diode-pumped passively mode-locked femtosecond Yb:CTGG laser,” Appl. Phys. B 115(2), 247–250 (2014).
[Crossref]

Cryst. Growth Des. (1)

E. Castellano-Hernández, M. D. Serrano, R. J. Jiménez Riobóo, C. Cascales, C. Zaldo, A. Jezowski, and P. A. Loiko, “Na modification of lanthanide doped Ca3Nb1.5Ga3.5O12-type laser garnets: Czochralski crystal growth and characterization,” Cryst. Growth Des. 16(3), 1480–1491 (2016).
[Crossref]

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[Crossref]

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[Crossref]

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[Crossref]

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S. Guo, D. Yuan, X. Zhang, X. Cheng, F. Yu, and X. Tao, “Growth and characterizations of calcium tantalum gallium garnet single crystal,” J. Cryst. Growth 311(1), 214–217 (2008).
[Crossref]

C. Ma, Y. Wang, X. Cheng, M. Xue, C. Zuo, C. Gao, S. Guo, and J. He, “Spectroscopic, thermal, and laser properties of disordered garnet Nd:CLTGG crystal,” J. Cryst. Growth 504, 44–50 (2018).
[Crossref]

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Y. Xue, N. Li, D. Wang, Q. Wang, B. Liu, Q. Song, D. Li, X. Xu, H. Gu, Z. Qin, and G. Xie, “Spectroscopic and laser properties of Tm:CNGG crystals grown by the micro-pulling-down method,” J. Lumin. 213, 36–39 (2019).
[Crossref]

J. Mater. Chem. C (2)

J. O. Álvarez-Pérez, J. M. Cano-Torres, A. Ruiz, M. D. Serrano, C. Cascales, and C. Zaldo, “A roadmap for laser optimization of Yb:Ca3(NbGa)5O12-CNGG-type single crystal garnets,” J. Mater. Chem. C 9(13), 4628–4642 (2021).
[Crossref]

M. D. Serrano, J. O. Álvarez-Pérez, C. Zaldo, J. Sanz, I. Sobrados, J. A. Alonso, C. Cascales, M. T. Fernández Díaz, and A. Jezowski, “Design of Yb3+ optical bandwidths by crystallographic modification of disordered calcium niobium gallium laser garnets,” J. Mater. Chem. C 5(44), 11481–11495 (2017).
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Data Availability

Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.

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Figures (11)

Fig. 1.
Fig. 1. (a) Photograph of the as-grown Tm:CLTGG crystal boule, the growth direction is [111]; (b) photograph of a polished laser element.
Fig. 2.
Fig. 2. X-ray powder diffraction study of Tm:CLTGG: (a) XRD pattern, (hkl) are Miller’s indices, vertical bars – theoretical pattern for Al1.23Ca3Fe0.99Hf2Si0.99O12 garnet; (b) Rietveld structure refinement: experimental (black), calculated (red) and differential (blue) XRD profiles, vertical dashes mark the Bragg reflections.
Fig. 3.
Fig. 3. Crystal structure of Tm:CLTGG: (a) projection of the crystal structure parallel to the a-c plane; (b) the variety of cationic distributions around Ca2+ | Tm3+ ions occupying the dodecahedral 24c sites: nearest-neighbor cations at: (i) dodecahedral 24c sites, (ii) octahedral 16a sites and (iii) tetrahedral 24d sites.
Fig. 4.
Fig. 4. Unpolarized RT Raman spectrum of the Tm:CLTGG crystal, λexc = 514 nm. Numbers indicate the band frequencies in cm-1. The Raman spectrum of Tm:CLNGG is given for comparison.
Fig. 5.
Fig. 5. Thermal properties of the Tm:CLTGG crystal as a function of temperature: (a) specific heat; (b) thermal diffusivity; (c) thermal conductivity.
Fig. 6.
Fig. 6. Absorption of the Tm:CLTGG crystal: (a) RT absorption spectrum; (b) absorption cross-sections, σabs, for the 3H63H4 Tm3+ transition; (c) Tauc plot for the evaluation of the optical bandgap (Eg).
Fig. 7.
Fig. 7. Near-infrared emission properties of the Tm:CLTGG crystal: (a) luminescence spectrum, λexc = 795 nm; (b,c) luminescence decay curves from the (b) 3F4 and (c) 3H4 Tm3+ states.
Fig. 8.
Fig. 8. Low-temperature (LT, 10 K) absorption and emission spectra for Tm3+ ions in the CLTGG crystal: (a) absorption, 3H63F4 transition; (b) emission, 3F43H6 and 3H43H6 transitions. The symbol “+” marks the assigned electronic transitions. Vertical dashes – crystal-field splitting in Tm:GGG after [23].
Fig. 9.
Fig. 9. 3H63F4 transition of Tm3+ ions in CLTGG: (a) absorption, σabs, and stimulated emission (SE), σSE, cross-sections; (b) gain cross-sections, σgain = σSE – (1 – β)σabs, where β = N2(3F4)/NTm is the inversion ratio.
Fig. 10.
Fig. 10. (a) Scheme of the diode-pumped compact Tm:CLTGG laser: LD – laser diode, PM – pump mirror, OC – output coupler, F – cut-on filter; (b) far-field output profile of the laser mode, TOC = 5%, Pabs = 4.0 W.
Fig. 11.
Fig. 11. Diode-pumped Tm:CLTGG laser: (a) input-output dependences, η – slope efficiency; (b) typical spectra of unpolarized laser emission measured at maximum Pabs.

Tables (5)

Tables Icon

Table 1. Fractional Atomic Coordinates, Occupancy Factors and Isotropic Displacement Parameters for Tm:CLTGG Crystal

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Table 2. Measured and Calculated Absorption Oscillator Strengths of Tm3+ ions in CLTGG crystala

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Table 3. Calculated Probabilities of Spontaneous Radiative Transitions of Tm3+ ions in CLTGG crystal (Obtained from the mJ-O Theory)a

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Table 4. Experimental Energy Levels of Tm3+ ions in CLTGG crystal

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Table 5. Laser Performancesa of Tm3+-doped Gallium Garnets

Equations (4)

Equations on this page are rendered with MathJax. Learn more.

S calc ED ( J J ) = k = 2 , 4 , 6 U ( k ) Ω k ,
U ( k ) = ( 4 f n ) S L J | | U k | | ( 4 f n ) S L J 2 .
S calc ED ( J J ) = k = 2 , 4 , 6 U ( k ) Ω ~ k ,
Ω ~ k = Ω k [ 1 + 2 α ( E J + E J 2 E f 0 ) ] .

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