Abstract

We report on the efficient, tunable, and selective frequency up-conversion of a supercontinuum spectrum via molecular modulation in a hydrogen-filled hollow-core photonic crystal fiber. The vibrational Q(1) Raman transition of hydrogen is excited in the fiber by a pump pre-pulse, enabling the excitation of a synchronous, collective oscillation of the molecules. This coherence wave is then used to up-shift the frequency of an arbitrarily weak, delayed probe pulse. Perfect phase-matching for this process is achieved by using higher order fiber modes and adjusting the pressure of the filling gas. Conversion efficiencies of ~50% are obtained within a tuning range of 25 THz.

© 2014 Optical Society of America

1. Introduction

Generation of spatiotemporal coherent light at frequencies that are not covered by standard lasing transitions has been an ongoing field of research since the invention of the first lasers. Many different methods based on nonlinear effects such as self-phase modulation [1] or high harmonic generation [2], have been developed to extend the accessible spectral regions from the far-infrared to the extreme ultraviolet and even beyond [3]. In this direction, stimulated Raman scattering (SRS) offers a versatile way to access new spectral regimes by the inelastic scattering of photons from molecules. In particular Raman-active gases, in contrast to solid-state materials, offer wide transparency windows and allow the generation of mutually coherent and equidistant spectral sidebands spanning several octaves [4]. In addition, optical signals of arbitrarily low amplitude can be shifted by the Raman frequency using the technique of molecular modulation [57]. In this approach, two intense laser signals with a frequency offset equal to the Raman shift drive the molecules coherently, creating a moving “coherence wave” that spatially modulates the refractive index. Under the correct conditions this wave can be used to shift the frequency of a probe signal. This approach has recently been proposed as an efficient means of generating tunable THz radiation from infrared pulses [8]. When implemented in bulk gas cells or wide-bore capillaries, however, all these methods require relatively high peak powers in the pump fields.

Gas-filled hollow-core photonic crystal fiber (HC-PCF) offers the twin advantages of tight modal confinement and long light-matter interaction lengths (not accessible in simple glass capillaries), which greatly reduces the peak power required for the observation of nonlinear phenomena [9, 10]. This makes it an ideal candidate for, e.g., the generation of multiple Raman sidebands [11, 12]. A further advantage is that the dispersion and nonlinearity can be widely tuned simply by varying the gas pressure [13].

In this paper we present an efficient fiber-based method for selective frequency up-conversion of a broadband optical signal using Raman-induced molecular modulation. By means of the differing dispersive properties of higher order modes [14, 15], perfect phase-matching for this up-shifting process is achieved in hydrogen-filled HC-PCF. In contrast with other approaches [57], most of the power of the probe beam is selectively converted to just a single band. The conversion efficiency of the linear scattering mechanism can be optimized for any single wavelength over a broad range by adjusting the gas pressure in the fiber.

2. Experimental set-up

The set-up is sketched in Fig. 1(a).We used a 1064 nm Q-switched laser delivering 3.8 ns pulses. The linearly-polarized beam was divided at a beam splitter. One part was used to generate a 150 nm wide supercontinuum (SC) signal in a 4 m-long solid-core PCF (core diameter 5.0 µm); this was used as the mixing signal. The other part, which we refer to as the pump beam, was diverted through a free-space delay line and combined with the SC mixing signal at a second beam splitter. The signals were then coupled through a pressure cell into a hydrogen-filled kagome-style HC-PCF [in Fig. 1(b)] with a length of 1 m and an area preserving core radius [16] of aAP = 19.3 µm. An optical spectrum analyzer was used to monitor the spectrum of the out-coupled light and a CCD camera imaged the near-field modal pattern.

 

Fig. 1 (a) Schematic of the experimental set-up. ND: neutral density filter; BP: band-pass filter; BS: beam-splitter. (b) Scanning electron micrograph of the fiber.

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3. Experimental results

3.1 Basic observations

When only the pump beam (ωP/2π = 282 THz) was launched into the gas-filled fiber, combs of both rotational and vibrational Raman lines were generated from noise [9, 11, 12]. The corresponding Raman shifts in hydrogen are ΩR/2π = 17.6 THz for the rotational S(1) Raman transition and ΩV/2π = 125 THz for the vibrational Q(1) Raman transition [17]. The measured spectrum is shown in Fig. 2(a) for a pump energy of 30 µJ and a gas pressure of 18.7 bar.

 

Fig. 2 Photon count-rate spectra normalized to the rate of the pump (the peak is not shown to enhance the other spectral lines). (a) Pump signal only. (b) SC mixing signal only. (c) Both pump and SC mixing signals. (d)-(h) Normalized near-field intensity distributions recorded at the end-face of the fiber filled with a gas pressure of 10 bar. (d) Pump beam, mainly coupled into LP01 mode; (e) mixing beam at 1080 nm; (f) first AS; (g) shifted SC; (h) pump with higher modal content in the LP11 mode.

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Note that the first vibrational Stokes line [ωS/2π = 157 THz, red solid line in Fig. 2(a,c)] was measured with an uncalibrated optical spectrum analyzer, so that its height does not scale with the rest of the spectrum. In contrast to the intense pump pulse, the spectrum of the relatively weak SC mixing beam, when launched in the absence of the pump, is not altered by propagating along the fiber [Fig. 2(b)]; this is because it is not powerful enough to initiate SRS. When, however, both pump and SC beams are simultaneously coupled into the fiber with an appropriate delay and modal content, two major effects can be observed [see Fig. 2(c)]. First, the SC spectrum seeds the first rotational Stokes line (ωrS/2π = 264 THz) and a slight increase in the absolute strength of the rotational sidebands is observed due to SRS. Second, a broad spectrum appears around the first vibrational anti-Stokes (AS) line (ωAS/2π = 406 THz). These new spectral components correspond to light that is frequency up-shifted relative to the mixing signal.

In the experiment, the up-shifted signal was strongest when the pump beam was mainly launched in an LP01 mode [Fig. 2(d)] while the mixing beam was both delayed by 1.2 ns with respect to the pump and misaligned so as to excite a mixture of LP01 and LP11 modes [Fig. 2(e)]. Under these conditions, the first vibrational AS signal [Fig. 2(f)], and the broad up-shifted spectral background located around it [Fig. 2(g)], were found to appear predominantly in the LP11 mode. Remarkably, the maximum photon count-rate in the shifted spectrum is of the same order of magnitude as that in the mixing beam, indicating that the process has high quantum efficiency.

3.2 Analysis of the results

The mechanism behind the generation of vibrational AS lines, and the up-shifted broad SC in the vicinity of the first AS band in Fig. 2(a,c), can be understood with the help of a dispersion diagram. This requires an accurate knowledge of the dispersion relation for the LP01 and LP11 modes of the kagome-PCF, which can be obtained from the expression [18]:

nmq(λ)=ngas2(λ,p)(λumq2πa(λ))2
where nmq is the effective index of an LPmq mode in kagome-PCF (m and q are the azimuthal and radial orders), ngas is the refractive index of the filling gas [19], p the gas pressure and umq the qth root of the mth order Bessel function of the first kind. a(λ)=aAP/(1+sλ2/(aAPt)) is an empirically derived wavelength-dependent effective core radius, where t = 200 nm is the core-wall thickness of our fiber and s = 0.059 a dimensionless parameter [18].

Figure 3(a) shows the dispersion curves for the LP01 and the LP11 modes of the evacuated kagome-PCF, plotted on a diagram of frequency versus wavevector difference (k0βmq), where k0=2π/λ, λ is the vacuum wavelength and βmq=k0nmq is the modal wavevector. Using Eq. (1), the phase index of the coherence wave created by Raman conversion from a signal at frequency ω to a signal at (ωΩ) may be written as nkl(ω)=cΩ1[βk(ω)βl(ωΩ)]where the subscript k denotes the mode at frequency ω and the superscript l the mode at (ω – Ω). In this way, we can define the coherence wave via the four-vector κkl(ω)=[Ωc1nkl(ω),Ω]. To simplify the notation, we will from now on use Ω to refer to the vibrational transition.

 

Fig. 3 (a) Dispersion diagram for the LP01 and LP11 modes at zero pressure. The horizontal lines mark the frequencies of the pump (P), first Stokes (S) and first anti-Stokes (AS) bands. The spectral widths of the mixing and the shifted SC signals are indicated by gray-scale shading. The backward (forward) sloping arrows indicate the four-vectors of the intra- (inter-) modal coherence waves. (b) Phase indices of different coherence waves as a function of the upper of the two frequencies used to generate them.

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In the first stage of the experiment, an intramodal coherence wave was created by launching an LP01 pump wave (frequency ωP) into the fiber with power sufficient to initiate SRS; the four-vector κ0101(ωP) of this coherence wave is indicated by the green arrow in Fig. 3(a). In the second stage, LP11 light at frequency ωP, already present in the fiber owing to launch misalignment, could be frequency up-shifted to the first vibrational AS within the LP11 mode by means of the previously excited κ0101(ωP) coherence wave. For this process to be efficient, phase-matching is essential, i.e., n0101(ωP)=n1111(ωAS). In the experiment it turned out that the phase mismatch was small, resulting in generation of a band of LP11 AS light [Fig. 2(a)]. Conversely, direct intramodal conversion to the LP01 AS was strongly suppressed owing to a higher degree of dephasing, which could not be compensated at any available pressure resulting in generation of a clean LP11 AS signal [Fig. 2(f)].

As we will show later, it is also possible to create a comparatively strong intermodal coherence wave κ1101(ωP) [Fig. 3(a)] by launching a higher proportion of pump power in the LP11 mode. This occurs through conversion of LP11 pump light to the LP01 Stokes band, seeded by light that is already present in that band. This coherence wave is then able to convert LP01 pump light to an AS signal in the LP11 mode [14, 15], if κ1101(ωP)κ1101(ωAS). Note that these up-shifting processes, mediated by pre-existing coherence waves, are not in general restricted to light at the original pump frequency. If the phase-mismatch is arranged to be sufficiently small, signals at other frequencies can be efficiently up-converted. Since the SC mixing signal was launched in a superposition of LP01 and LP11 modes [Fig. 2(e)], SC light in the LP11 mode could also be up-shifted by the κ0101(ωP) coherence wave, resulting in a broad spectral band around the AS frequency [Fig. 2(c)].

Possible phase-matched transitions are illustrated in Fig. 3(b) for a pressure of 18.7 bar. The dashed vertical lines mark coherence waves with identical phase indices. The green dots at the lower end of these lines indicate the indices of the coherence waves generated when SRS occurs at a pump frequency of 282 THz. These waves can be used for phase-matched transfer of light to an AS band in the vicinity of the upper green dots. In particular, the intermodal coherence wave with index n1101(ωP) can be used for efficient generation of light at ~430 THz, and the intramodal coherence wave with index n0101(ωP) permits efficient up-conversion to ~400 THz in the LP11 mode. Note that for symmetry reasons a coherence wave generated by intermodal SRS cannot be used for intramodal conversion (dotted line marked with a red cross) [14].

In the experiments, rotational excitations are also present, leading to the formation of rotational sidebands [Fig. 2(a)]. These bands are however quite weak since both SC and pump signals are linearly polarized, favoring vibrational transitions. Moreover, in hydrogen the vibrational gain is much higher than the rotational [17]. Thus, although the scattering of photons by the rotational coherence wave cannot be excluded, its efficiency can be kept extremely low if a SC mixing beam with a relatively narrow spectral width [see Fig. 2(b)] is used, so as to avoid strong seeding of rotational SRS.

3.3 Linear dependence and conversion efficiency

Given the presence of a sufficiently strong phase-matched coherence wave, the conversion probability for photons belonging to a subsequent mixing signal is expected to be independent of the power of the mixing signal itself, provided it is sufficiently weak [5]. We have studied the linearity of this scattering process by attenuating the SC mixing beam using a set of neutral density filters. The intensities of both the mixing beam and the shifted SC were measured at the output of the fiber while keeping the pump energy constant at 30 µJ and the pressure at 14 bar. The proportionality between both shifted and mixing signals observed in Fig. 4(a) indicates that the mixing does not noticeably influence the strength of the coherence wave. We can therefore infer that this scattering process occurs without any threshold and can be used for shifting of arbitrarily weak signals.

 

Fig. 4 (a) Comparison of the intensities of shifted and mixing signals, normalized to their values in the absence of any ND filters. The black line is a linear fit of the experimental data, yielding a slope of 0.997 ± 0.013. (b) Conversion efficiency η of the up-shifting process (solid curve). The dashed curve shows the analytical conversion efficiency after fitting to Eq. (3).

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Calibrated spectra as those shown in Fig. 2, allow estimation of the absolute photon number conversion efficiency η(ω)=NP,M(ω)/NM(ωΩ) of the scattering process, where NP,M(ω) is the photon count-rate recorded with both pump and mixing beams present in the fiber [Fig. 2(c)], and NM(ωΩ) is the reference spectrum corresponding to the original mixing beam [Fig. 2(b)].

The resulting conversion efficiency η(ω) is plotted in Fig. 4(b) for p = 18 bar and a pump pulse energy of 18 µJ. The maximum value η0.79 is located at 399 THz, which corresponds to the frequency of perfect phase-matching for this specific pressure. Apart from this isolated peak, the average conversion efficiency turns out to be ~50%. Note that this is likely to be an underestimate since only the LP11 content of the original mixing beam (which is a mixture of LP01 and LP11 modes) can be converted by the excited κ0101(ωP) coherence wave because of the need for phase-matching [Fig. 3(a)].

The observed gain bandwidth of η(ω), shows that the up-shifting process can tolerate a certain amount of phase-mismatch. This can be explained by modeling the coupling of the mixing beam to the AS band. The evolution with z of the electric field amplitudes of the mixing Emi(ωΩ,z) and shifted Esh(ω,z) signals can be written as:

Eshz=iζEmiiϑ(ω)2EshEmiz=iζ(ωΩ)ωEsh+iϑ(ω)2Emi,
where ϑ(ω)=Ωc1[n0101(ωP)n1111(ω)] is the rate of phase-mismatch of the coherence waves involved. The coupling constant ζ defines the characteristics of the scattering mechanism mediated by the pre-existing coherence wave κ0101(ωP), which is assumed for simplicity to be uniform along the fiber axis. Conservation of the total photon number is guaranteed by the factor (ωΩ)/ω. Analytical solution of these equations yields:
η(ω,L)=(ωΩ)ω|Esh(ω,L)|2|Emi(ωΩ,0)|2=(ωΩ)ωζ2γ2sin2(γL)
where γ2=(ϑ2/4)+ζ2(ωΩ)/ω and L is the effective coupling length. A least-squares fit of Eq. (3) to the results shown in Fig. 4(b) is obtained for ζ = 5.2 m−1 and L = 0.17 m [blue dashed line in Fig. 4(b)]. This is shorter than the total length (1 m) of fiber used, reflecting that the coherence wave depends on the strength of the Stokes signal, which reaches its maximum towards the fiber end. Despite its simplicity, this model reproduces the observed bandwidth of ~6 THz.

3.4 Pressure dependence of the conversion efficiency

Perfect phase-matching of the up-shifting process, which occurs when κ0101(ωP)=κ1111(ω), depends on both frequency and pressure. In order to quantify this feature of the system, the hydrogen pressure inside the HC-PCF was tuned from 1 to 37.5 bar, and the conversion efficiency η in a given frequency range was measured at each step. The results are shown in Fig. 5(a).The spectral component for which η is maximum shifts smoothly from 395 THz to 420 THz with increasing pressure. For lower pressures (below ~10 bar) and hence lower molecular densities, η drops rapidly owing to decreasing Raman gain [20]. At higher pressures η fluctuates slightly on a linear scale up to 35 bar, with an average value of ~50% and some isolated peaks reaching ~80% at 18 and 30 bar. Remarkably, these measured conversion efficiencies to a single sideband are about a factor of two higher, and the pulse energies 100 times lower, than the values previously reported in experiments performed using nanosecond pump pulses [6].

 

Fig. 5 Pressure-dependence of the conversion efficiency at different frequencies. (a) Pump beam mainly in the LP01 mode. (b) Pump beam with a high LP11 modal content. The dashed and solid lines correspond to numerical curves of perfect phase-matching for intramodal and intermodal coherence waves. The dotted line in (a) indicates the measurement in Fig. 4(b)

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We have verified that the overall shape of the data in Fig. 5(a) follows the condition for perfect phase-matching of the intramodal coherence waves n0101(ωP)=n1111(ω), in terms both of frequency and pressure (dashed line).

3.5 Effects of intermodal coherence waves

To explore the role of the intermodal coherence waves, the pressure dependence of η(ω) was monitored while adjusting the coupling of the pump beam so as to increase the fraction of the total power in the LP11 mode [a typical near-field profile is shown in Fig. 2(h)]. The measured conversion efficiencies are shown in Fig. 5(b) for a pump pulse energy of 36 µJ. The branch of high η(ω) mediated by the intramodal coherence wave [see Fig. 5(a)] is still visible in this measurement, although the absolute values of η(ω) are slightly lower. However, the most interesting feature here is the appearance of a second branch crossing the first one at the AS frequency. We attribute this new observation to the excitation of the intermodal coherence wave κ1101(ωP). The phase-matching condition for this intermodal scattering process n1101(ωP)=n1101(ω) is plotted in Fig. 5(b), again displaying good agreement with the experimental results (yellow solid line). Interestingly, in the case of single-frequency AS generation both scattering branches are usually degenerate and so phase-matched at the same pressure [15]. This can be directly understood from the diagram in Fig. 5(b), as the generation of the first AS signal corresponds to the crossing point of both intramodal and intermodal phase-matching lines. In contrast, this degeneracy between both branches vanishes when the up-shifted photons do not correspond to the AS line. The use of a SC mixing beam allows, for first time, to unambiguously access the non-degenerate regime, so that the intramodal and intermodal scattering schemes are perfectly phase-matched at different pressures for a given frequency as shown in Fig. 5(b).

4. Conclusions

In conclusion, the generation of coherence waves in a hydrogen-filled HC-PCF provides a simple and versatile means of achieving efficient and selective frequency conversion of arbitrary signals without any threshold. Since the dispersion of the different fiber modes changes with the gas pressure, perfect phase-matching can be finely tuned over a broad frequency range. Conversion efficiencies of ~50% are achieved over broad spectral bandwidths despite using pump pulse energies that are two orders of magnitude lower than in previous experiments [6]. Similar to the demonstrated up-shifting process, down-shifting would in principle be possible in our experimental set-up using a mixing beam with a frequency close to the AS band. In fact, our approach allows for both up- and down-shifting of arbitrary signals provided that suitable parameters (such as core diameter, pressure, pump wavelength and low attenuation at all the relevant wavelengths) are available. The technique may find applications in the development of novel tunable laser sources and highly sensitive in-fiber coherent anti-Stokes Raman spectroscopy of trace gases [21].

Acknowledgments

We would like to thank Martin Finger and Nicolas Joly for fruitful discussions.

References and links

1. R. W. Boyd, Nonlinear Optics (Academic, 2008).

2. P. Gibbon, “High-order harmonic generation in plasmas,” IEEE J. Quantum Electron. 33(11), 1915–1924 (1997). [CrossRef]  

3. T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012). [CrossRef]   [PubMed]  

4. A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris, “Raman generation by phased and antiphased molecular states,” Phys. Rev. Lett. 85(3), 562–565 (2000). [CrossRef]   [PubMed]  

5. A. Nazarkin, G. Korn, M. Wittmann, and T. Elsaesser, “Generation of multiple phase-locked Stokes and anti-Stokes components in an impulsively excited Raman medium,” Phys. Rev. Lett. 83(13), 2560–2563 (1999). [CrossRef]  

6. J. Q. Liang, M. Katsuragawa, F. L. Kien, and K. Hakuta, “Sideband generation using strongly driven Raman coherence in solid hydrogen,” Phys. Rev. Lett. 85(12), 2474–2477 (2000). [CrossRef]   [PubMed]  

7. J. J. Weber, J. T. Green, and D. D. Yavuz, “17 THz continuous-wave optical modulator,” Phys. Rev. A 85(1), 013805 (2012). [CrossRef]  

8. D. D. Yavuz and J. J. Weber, “Tunable source of terahertz radiation using molecular modulation,” Opt. Lett. 37(20), 4191–4193 (2012). [CrossRef]   [PubMed]  

9. F. Benabid, J. C. Knight, G. Antonopoulos, and P. St. J. Russell, “Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” Science 298(5592), 399–402 (2002). [CrossRef]   [PubMed]  

10. P. S. Donvalkar, V. Venkataraman, S. Clemmen, K. Saha, and A. L. Gaeta, “Frequency translation via four-wave mixing Bragg scattering in Rb filled photonic bandgap fibers,” Opt. Lett. 39(6), 1557–1560 (2014). [CrossRef]   [PubMed]  

11. F. Couny, F. Benabid, P. J. Roberts, P. S. Light, and M. G. Raymer, “Generation and photonic guidance of multi-octave optical-frequency combs,” Science 318(5853), 1118–1121 (2007). [CrossRef]   [PubMed]  

12. A. Abdolvand, A. M. Walser, M. Ziemienczuk, T. Nguyen, and P. St. J. Russell, “Generation of a phase-locked Raman frequency comb in gas-filled hollow-core photonic crystal fiber,” Opt. Lett. 37(21), 4362–4364 (2012). [CrossRef]   [PubMed]  

13. J. C. Travers, W. Chang, J. Nold, N. Y. Joly, and P. St. J. Russell, “Ultrafast nonlinear optics in gas-filled hollow-core photonic crystal fibers,” J. Opt. Soc. Am. B 28, A11–A26 (2011). [CrossRef]  

14. M. Ziemienczuk, A. M. Walser, A. Abdolvand, and P. St. J. Russell, “Intermodal stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” J. Opt. Soc. Am. B 29(7), 1563–1568 (2012). [CrossRef]  

15. B. M. Trabold, A. Abdolvand, T. G. Euser, and P. St. J. Russell, “Efficient anti-Stokes generation via intermodal stimulated Raman scattering in gas-filled hollow-core PCF,” Opt. Express 21(24), 29711–29718 (2013). [CrossRef]   [PubMed]  

16. J. Nold, P. Hölzer, N. Y. Joly, G. K. L. Wong, A. Nazarkin, A. Podlipensky, M. Scharrer, and P. St. J. Russell, “Pressure-controlled phase matching to third harmonic in Ar-filled hollow-core photonic crystal fiber,” Opt. Lett. 35(17), 2922–2924 (2010). [CrossRef]   [PubMed]  

17. J. F. Reintjes, Handbook of Laser Science and Technology, Supplement 2: Optical Materials (CRC, 1995).

18. M. A. Finger, N. Y. Joly, T. Weiss, and P. St. J. Russell, “Accuracy of the capillary approximation for gas-filled kagomé-style photonic crystal fibers,” Opt. Lett. 39(4), 821–824 (2014). [CrossRef]   [PubMed]  

19. E. R. Peck and S. Huang, “Refractivity and dispersion of hydrogen in the visible and near infrared,” J. Opt. Soc. Am. 67(11), 1550–1554 (1977). [CrossRef]  

20. F. Couny, O. Carraz, and F. Benabid, “Control of transient regime of stimulated Raman scattering using hollow-core PCF,” J. Opt. Soc. Am. B 26(6), 1209–1215 (2009). [CrossRef]  

21. S. O. Konorov, A. B. Fedotov, A. M. Zheltikov, and R. B. Miles, “Phase-matched four-wave mixing and sensing of water molecules by coherent anti-Stokes Raman scattering in large-core-area hollow photonic-crystal fibers,” J. Opt. Soc. Am. B 22(9), 2049–2053 (2005). [CrossRef]  

References

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  1. R. W. Boyd, Nonlinear Optics (Academic, 2008).
  2. P. Gibbon, “High-order harmonic generation in plasmas,” IEEE J. Quantum Electron. 33(11), 1915–1924 (1997).
    [Crossref]
  3. T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
    [Crossref] [PubMed]
  4. A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris, “Raman generation by phased and antiphased molecular states,” Phys. Rev. Lett. 85(3), 562–565 (2000).
    [Crossref] [PubMed]
  5. A. Nazarkin, G. Korn, M. Wittmann, and T. Elsaesser, “Generation of multiple phase-locked Stokes and anti-Stokes components in an impulsively excited Raman medium,” Phys. Rev. Lett. 83(13), 2560–2563 (1999).
    [Crossref]
  6. J. Q. Liang, M. Katsuragawa, F. L. Kien, and K. Hakuta, “Sideband generation using strongly driven Raman coherence in solid hydrogen,” Phys. Rev. Lett. 85(12), 2474–2477 (2000).
    [Crossref] [PubMed]
  7. J. J. Weber, J. T. Green, and D. D. Yavuz, “17 THz continuous-wave optical modulator,” Phys. Rev. A 85(1), 013805 (2012).
    [Crossref]
  8. D. D. Yavuz and J. J. Weber, “Tunable source of terahertz radiation using molecular modulation,” Opt. Lett. 37(20), 4191–4193 (2012).
    [Crossref] [PubMed]
  9. F. Benabid, J. C. Knight, G. Antonopoulos, and P. St. J. Russell, “Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” Science 298(5592), 399–402 (2002).
    [Crossref] [PubMed]
  10. P. S. Donvalkar, V. Venkataraman, S. Clemmen, K. Saha, and A. L. Gaeta, “Frequency translation via four-wave mixing Bragg scattering in Rb filled photonic bandgap fibers,” Opt. Lett. 39(6), 1557–1560 (2014).
    [Crossref] [PubMed]
  11. F. Couny, F. Benabid, P. J. Roberts, P. S. Light, and M. G. Raymer, “Generation and photonic guidance of multi-octave optical-frequency combs,” Science 318(5853), 1118–1121 (2007).
    [Crossref] [PubMed]
  12. A. Abdolvand, A. M. Walser, M. Ziemienczuk, T. Nguyen, and P. St. J. Russell, “Generation of a phase-locked Raman frequency comb in gas-filled hollow-core photonic crystal fiber,” Opt. Lett. 37(21), 4362–4364 (2012).
    [Crossref] [PubMed]
  13. J. C. Travers, W. Chang, J. Nold, N. Y. Joly, and P. St. J. Russell, “Ultrafast nonlinear optics in gas-filled hollow-core photonic crystal fibers,” J. Opt. Soc. Am. B 28, A11–A26 (2011).
    [Crossref]
  14. M. Ziemienczuk, A. M. Walser, A. Abdolvand, and P. St. J. Russell, “Intermodal stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” J. Opt. Soc. Am. B 29(7), 1563–1568 (2012).
    [Crossref]
  15. B. M. Trabold, A. Abdolvand, T. G. Euser, and P. St. J. Russell, “Efficient anti-Stokes generation via intermodal stimulated Raman scattering in gas-filled hollow-core PCF,” Opt. Express 21(24), 29711–29718 (2013).
    [Crossref] [PubMed]
  16. J. Nold, P. Hölzer, N. Y. Joly, G. K. L. Wong, A. Nazarkin, A. Podlipensky, M. Scharrer, and P. St. J. Russell, “Pressure-controlled phase matching to third harmonic in Ar-filled hollow-core photonic crystal fiber,” Opt. Lett. 35(17), 2922–2924 (2010).
    [Crossref] [PubMed]
  17. J. F. Reintjes, Handbook of Laser Science and Technology, Supplement 2: Optical Materials (CRC, 1995).
  18. M. A. Finger, N. Y. Joly, T. Weiss, and P. St. J. Russell, “Accuracy of the capillary approximation for gas-filled kagomé-style photonic crystal fibers,” Opt. Lett. 39(4), 821–824 (2014).
    [Crossref] [PubMed]
  19. E. R. Peck and S. Huang, “Refractivity and dispersion of hydrogen in the visible and near infrared,” J. Opt. Soc. Am. 67(11), 1550–1554 (1977).
    [Crossref]
  20. F. Couny, O. Carraz, and F. Benabid, “Control of transient regime of stimulated Raman scattering using hollow-core PCF,” J. Opt. Soc. Am. B 26(6), 1209–1215 (2009).
    [Crossref]
  21. S. O. Konorov, A. B. Fedotov, A. M. Zheltikov, and R. B. Miles, “Phase-matched four-wave mixing and sensing of water molecules by coherent anti-Stokes Raman scattering in large-core-area hollow photonic-crystal fibers,” J. Opt. Soc. Am. B 22(9), 2049–2053 (2005).
    [Crossref]

2014 (2)

2013 (1)

2012 (5)

A. Abdolvand, A. M. Walser, M. Ziemienczuk, T. Nguyen, and P. St. J. Russell, “Generation of a phase-locked Raman frequency comb in gas-filled hollow-core photonic crystal fiber,” Opt. Lett. 37(21), 4362–4364 (2012).
[Crossref] [PubMed]

J. J. Weber, J. T. Green, and D. D. Yavuz, “17 THz continuous-wave optical modulator,” Phys. Rev. A 85(1), 013805 (2012).
[Crossref]

D. D. Yavuz and J. J. Weber, “Tunable source of terahertz radiation using molecular modulation,” Opt. Lett. 37(20), 4191–4193 (2012).
[Crossref] [PubMed]

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

M. Ziemienczuk, A. M. Walser, A. Abdolvand, and P. St. J. Russell, “Intermodal stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” J. Opt. Soc. Am. B 29(7), 1563–1568 (2012).
[Crossref]

2011 (1)

2010 (1)

2009 (1)

2007 (1)

F. Couny, F. Benabid, P. J. Roberts, P. S. Light, and M. G. Raymer, “Generation and photonic guidance of multi-octave optical-frequency combs,” Science 318(5853), 1118–1121 (2007).
[Crossref] [PubMed]

2005 (1)

2002 (1)

F. Benabid, J. C. Knight, G. Antonopoulos, and P. St. J. Russell, “Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” Science 298(5592), 399–402 (2002).
[Crossref] [PubMed]

2000 (2)

A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris, “Raman generation by phased and antiphased molecular states,” Phys. Rev. Lett. 85(3), 562–565 (2000).
[Crossref] [PubMed]

J. Q. Liang, M. Katsuragawa, F. L. Kien, and K. Hakuta, “Sideband generation using strongly driven Raman coherence in solid hydrogen,” Phys. Rev. Lett. 85(12), 2474–2477 (2000).
[Crossref] [PubMed]

1999 (1)

A. Nazarkin, G. Korn, M. Wittmann, and T. Elsaesser, “Generation of multiple phase-locked Stokes and anti-Stokes components in an impulsively excited Raman medium,” Phys. Rev. Lett. 83(13), 2560–2563 (1999).
[Crossref]

1997 (1)

P. Gibbon, “High-order harmonic generation in plasmas,” IEEE J. Quantum Electron. 33(11), 1915–1924 (1997).
[Crossref]

1977 (1)

Abdolvand, A.

Ališauskas, S.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Andriukaitis, G.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Antonopoulos, G.

F. Benabid, J. C. Knight, G. Antonopoulos, and P. St. J. Russell, “Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” Science 298(5592), 399–402 (2002).
[Crossref] [PubMed]

Arpin, P.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Balciunas, T.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Baltuška, A.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Becker, A.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Benabid, F.

F. Couny, O. Carraz, and F. Benabid, “Control of transient regime of stimulated Raman scattering using hollow-core PCF,” J. Opt. Soc. Am. B 26(6), 1209–1215 (2009).
[Crossref]

F. Couny, F. Benabid, P. J. Roberts, P. S. Light, and M. G. Raymer, “Generation and photonic guidance of multi-octave optical-frequency combs,” Science 318(5853), 1118–1121 (2007).
[Crossref] [PubMed]

F. Benabid, J. C. Knight, G. Antonopoulos, and P. St. J. Russell, “Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” Science 298(5592), 399–402 (2002).
[Crossref] [PubMed]

Brown, S.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Carraz, O.

Chang, W.

Chen, M.-C.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Clemmen, S.

Couny, F.

F. Couny, O. Carraz, and F. Benabid, “Control of transient regime of stimulated Raman scattering using hollow-core PCF,” J. Opt. Soc. Am. B 26(6), 1209–1215 (2009).
[Crossref]

F. Couny, F. Benabid, P. J. Roberts, P. S. Light, and M. G. Raymer, “Generation and photonic guidance of multi-octave optical-frequency combs,” Science 318(5853), 1118–1121 (2007).
[Crossref] [PubMed]

Donvalkar, P. S.

Elsaesser, T.

A. Nazarkin, G. Korn, M. Wittmann, and T. Elsaesser, “Generation of multiple phase-locked Stokes and anti-Stokes components in an impulsively excited Raman medium,” Phys. Rev. Lett. 83(13), 2560–2563 (1999).
[Crossref]

Euser, T. G.

Fedotov, A. B.

Finger, M. A.

Gaeta, A. L.

P. S. Donvalkar, V. Venkataraman, S. Clemmen, K. Saha, and A. L. Gaeta, “Frequency translation via four-wave mixing Bragg scattering in Rb filled photonic bandgap fibers,” Opt. Lett. 39(6), 1557–1560 (2014).
[Crossref] [PubMed]

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Gibbon, P.

P. Gibbon, “High-order harmonic generation in plasmas,” IEEE J. Quantum Electron. 33(11), 1915–1924 (1997).
[Crossref]

Green, J. T.

J. J. Weber, J. T. Green, and D. D. Yavuz, “17 THz continuous-wave optical modulator,” Phys. Rev. A 85(1), 013805 (2012).
[Crossref]

Hakuta, K.

J. Q. Liang, M. Katsuragawa, F. L. Kien, and K. Hakuta, “Sideband generation using strongly driven Raman coherence in solid hydrogen,” Phys. Rev. Lett. 85(12), 2474–2477 (2000).
[Crossref] [PubMed]

Harris, S. E.

A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris, “Raman generation by phased and antiphased molecular states,” Phys. Rev. Lett. 85(3), 562–565 (2000).
[Crossref] [PubMed]

Hernández-García, C.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Hölzer, P.

Huang, S.

Jaron-Becker, A.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Joly, N. Y.

Kapteyn, H. C.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Katsuragawa, M.

J. Q. Liang, M. Katsuragawa, F. L. Kien, and K. Hakuta, “Sideband generation using strongly driven Raman coherence in solid hydrogen,” Phys. Rev. Lett. 85(12), 2474–2477 (2000).
[Crossref] [PubMed]

Kien, F. L.

J. Q. Liang, M. Katsuragawa, F. L. Kien, and K. Hakuta, “Sideband generation using strongly driven Raman coherence in solid hydrogen,” Phys. Rev. Lett. 85(12), 2474–2477 (2000).
[Crossref] [PubMed]

Knight, J. C.

F. Benabid, J. C. Knight, G. Antonopoulos, and P. St. J. Russell, “Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” Science 298(5592), 399–402 (2002).
[Crossref] [PubMed]

Konorov, S. O.

Korn, G.

A. Nazarkin, G. Korn, M. Wittmann, and T. Elsaesser, “Generation of multiple phase-locked Stokes and anti-Stokes components in an impulsively excited Raman medium,” Phys. Rev. Lett. 83(13), 2560–2563 (1999).
[Crossref]

Liang, J. Q.

J. Q. Liang, M. Katsuragawa, F. L. Kien, and K. Hakuta, “Sideband generation using strongly driven Raman coherence in solid hydrogen,” Phys. Rev. Lett. 85(12), 2474–2477 (2000).
[Crossref] [PubMed]

Light, P. S.

F. Couny, F. Benabid, P. J. Roberts, P. S. Light, and M. G. Raymer, “Generation and photonic guidance of multi-octave optical-frequency combs,” Science 318(5853), 1118–1121 (2007).
[Crossref] [PubMed]

Miles, R. B.

Mücke, O. D.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Murnane, M. M.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Nazarkin, A.

J. Nold, P. Hölzer, N. Y. Joly, G. K. L. Wong, A. Nazarkin, A. Podlipensky, M. Scharrer, and P. St. J. Russell, “Pressure-controlled phase matching to third harmonic in Ar-filled hollow-core photonic crystal fiber,” Opt. Lett. 35(17), 2922–2924 (2010).
[Crossref] [PubMed]

A. Nazarkin, G. Korn, M. Wittmann, and T. Elsaesser, “Generation of multiple phase-locked Stokes and anti-Stokes components in an impulsively excited Raman medium,” Phys. Rev. Lett. 83(13), 2560–2563 (1999).
[Crossref]

Nguyen, T.

Nold, J.

Peck, E. R.

Plaja, L.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Podlipensky, A.

Popmintchev, D.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Popmintchev, T.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Pugzlys, A.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Raymer, M. G.

F. Couny, F. Benabid, P. J. Roberts, P. S. Light, and M. G. Raymer, “Generation and photonic guidance of multi-octave optical-frequency combs,” Science 318(5853), 1118–1121 (2007).
[Crossref] [PubMed]

Roberts, P. J.

F. Couny, F. Benabid, P. J. Roberts, P. S. Light, and M. G. Raymer, “Generation and photonic guidance of multi-octave optical-frequency combs,” Science 318(5853), 1118–1121 (2007).
[Crossref] [PubMed]

Russell, P. St. J.

M. A. Finger, N. Y. Joly, T. Weiss, and P. St. J. Russell, “Accuracy of the capillary approximation for gas-filled kagomé-style photonic crystal fibers,” Opt. Lett. 39(4), 821–824 (2014).
[Crossref] [PubMed]

B. M. Trabold, A. Abdolvand, T. G. Euser, and P. St. J. Russell, “Efficient anti-Stokes generation via intermodal stimulated Raman scattering in gas-filled hollow-core PCF,” Opt. Express 21(24), 29711–29718 (2013).
[Crossref] [PubMed]

M. Ziemienczuk, A. M. Walser, A. Abdolvand, and P. St. J. Russell, “Intermodal stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” J. Opt. Soc. Am. B 29(7), 1563–1568 (2012).
[Crossref]

A. Abdolvand, A. M. Walser, M. Ziemienczuk, T. Nguyen, and P. St. J. Russell, “Generation of a phase-locked Raman frequency comb in gas-filled hollow-core photonic crystal fiber,” Opt. Lett. 37(21), 4362–4364 (2012).
[Crossref] [PubMed]

J. C. Travers, W. Chang, J. Nold, N. Y. Joly, and P. St. J. Russell, “Ultrafast nonlinear optics in gas-filled hollow-core photonic crystal fibers,” J. Opt. Soc. Am. B 28, A11–A26 (2011).
[Crossref]

J. Nold, P. Hölzer, N. Y. Joly, G. K. L. Wong, A. Nazarkin, A. Podlipensky, M. Scharrer, and P. St. J. Russell, “Pressure-controlled phase matching to third harmonic in Ar-filled hollow-core photonic crystal fiber,” Opt. Lett. 35(17), 2922–2924 (2010).
[Crossref] [PubMed]

F. Benabid, J. C. Knight, G. Antonopoulos, and P. St. J. Russell, “Stimulated Raman scattering in hydrogen-filled hollow-core photonic crystal fiber,” Science 298(5592), 399–402 (2002).
[Crossref] [PubMed]

Saha, K.

Scharrer, M.

Schrauth, S. E.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Shim, B.

T. Popmintchev, M.-C. Chen, D. Popmintchev, P. Arpin, S. Brown, S. Ališauskas, G. Andriukaitis, T. Balčiunas, O. D. Mücke, A. Pugzlys, A. Baltuška, B. Shim, S. E. Schrauth, A. L. Gaeta, C. Hernández-García, L. Plaja, A. Becker, A. Jaron-Becker, M. M. Murnane, and H. C. Kapteyn, “Bright coherent ultrahigh harmonics in the keV X-ray regime from mid-infrared femtosecond lasers,” Science 336(6086), 1287–1291 (2012).
[Crossref] [PubMed]

Sokolov, A. V.

A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris, “Raman generation by phased and antiphased molecular states,” Phys. Rev. Lett. 85(3), 562–565 (2000).
[Crossref] [PubMed]

Trabold, B. M.

Travers, J. C.

Venkataraman, V.

Walker, D. R.

A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris, “Raman generation by phased and antiphased molecular states,” Phys. Rev. Lett. 85(3), 562–565 (2000).
[Crossref] [PubMed]

Walser, A. M.

Weber, J. J.

D. D. Yavuz and J. J. Weber, “Tunable source of terahertz radiation using molecular modulation,” Opt. Lett. 37(20), 4191–4193 (2012).
[Crossref] [PubMed]

J. J. Weber, J. T. Green, and D. D. Yavuz, “17 THz continuous-wave optical modulator,” Phys. Rev. A 85(1), 013805 (2012).
[Crossref]

Weiss, T.

Wittmann, M.

A. Nazarkin, G. Korn, M. Wittmann, and T. Elsaesser, “Generation of multiple phase-locked Stokes and anti-Stokes components in an impulsively excited Raman medium,” Phys. Rev. Lett. 83(13), 2560–2563 (1999).
[Crossref]

Wong, G. K. L.

Yavuz, D. D.

J. J. Weber, J. T. Green, and D. D. Yavuz, “17 THz continuous-wave optical modulator,” Phys. Rev. A 85(1), 013805 (2012).
[Crossref]

D. D. Yavuz and J. J. Weber, “Tunable source of terahertz radiation using molecular modulation,” Opt. Lett. 37(20), 4191–4193 (2012).
[Crossref] [PubMed]

A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris, “Raman generation by phased and antiphased molecular states,” Phys. Rev. Lett. 85(3), 562–565 (2000).
[Crossref] [PubMed]

Yin, G. Y.

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Figures (5)

Fig. 1
Fig. 1 (a) Schematic of the experimental set-up. ND: neutral density filter; BP: band-pass filter; BS: beam-splitter. (b) Scanning electron micrograph of the fiber.
Fig. 2
Fig. 2 Photon count-rate spectra normalized to the rate of the pump (the peak is not shown to enhance the other spectral lines). (a) Pump signal only. (b) SC mixing signal only. (c) Both pump and SC mixing signals. (d)-(h) Normalized near-field intensity distributions recorded at the end-face of the fiber filled with a gas pressure of 10 bar. (d) Pump beam, mainly coupled into LP01 mode; (e) mixing beam at 1080 nm; (f) first AS; (g) shifted SC; (h) pump with higher modal content in the LP11 mode.
Fig. 3
Fig. 3 (a) Dispersion diagram for the LP01 and LP11 modes at zero pressure. The horizontal lines mark the frequencies of the pump (P), first Stokes (S) and first anti-Stokes (AS) bands. The spectral widths of the mixing and the shifted SC signals are indicated by gray-scale shading. The backward (forward) sloping arrows indicate the four-vectors of the intra- (inter-) modal coherence waves. (b) Phase indices of different coherence waves as a function of the upper of the two frequencies used to generate them.
Fig. 4
Fig. 4 (a) Comparison of the intensities of shifted and mixing signals, normalized to their values in the absence of any ND filters. The black line is a linear fit of the experimental data, yielding a slope of 0.997 ± 0.013. (b) Conversion efficiency η of the up-shifting process (solid curve). The dashed curve shows the analytical conversion efficiency after fitting to Eq. (3).
Fig. 5
Fig. 5 Pressure-dependence of the conversion efficiency at different frequencies. (a) Pump beam mainly in the LP01 mode. (b) Pump beam with a high LP11 modal content. The dashed and solid lines correspond to numerical curves of perfect phase-matching for intramodal and intermodal coherence waves. The dotted line in (a) indicates the measurement in Fig. 4(b)

Equations (3)

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n mq (λ)= n gas 2 (λ,p) ( λ u mq 2πa(λ) ) 2
E sh z =iζ E mi i ϑ(ω) 2 E sh E mi z =iζ (ωΩ) ω E sh +i ϑ(ω) 2 E mi ,
η(ω,L)= ( ωΩ ) ω | E sh (ω,L) | 2 | E mi (ωΩ,0) | 2 = ( ωΩ ) ω ζ 2 γ 2 sin 2 (γL)

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