Abstract

Single-frequency blue laser sources are of interest for an increasing number of emerging applications but are still difficult to implement and expensive to fabricate and suffer from poor robustness. Here a novel and universal grating design to realize distributed optical feedback in visible semiconductor laser diodes (LDs) was demonstrated on a semipolar InGaN LD, and its unique effect on the laser performance was investigated. For the first time, to the best of our knowledge, a low threshold voltage, record-high power output, and ultra-narrow single-mode lasing were simultaneously obtained on the new laser structure with a thinner p-GaN layer and a third-order phase-shifted embedded dielectric grating. Under continuous-wave operation, such 450 nm lasers achieved 35 dB side-mode suppression ratio, less than 2 pm FWHM, and near 400 mW total output power at room temperature.

© 2020 Optical Society of America

High-power single-frequency laser sources have been in growing demand for many applications, e.g., coherent detection [1], interferometric systems [2], visible light communications [3], and optical characterization systems [4]. Typical solutions include tunable dye lasers [5], which exhibit a relatively large linewidth, or costly and bulky external cavity lasers [6]. Properly engineered distributed feedback (DFB) laser diodes (LDs) are well known for their excellent portability, easy integration, and ability to offer robust single longitudinal mode stability, both in their resistance to mode hopping with environmental changes, and in basic side-mode suppression characteristics [79]. Previous reports on the designs of GaN DFB-LDs include regrowth-based gain-coupled grating [10], high-order sidewall grating [11], surface grating [12], etc. However, all the designs so far inevitably involve dry etching process on p-GaN, which have been shown detrimental to the laser performance. In addition, previous works with uniform gratings rely on either additional reflections from front and back mirrors at random phases or asymmetrical coating on the facets to split the mode degeneracy, making it often low-yield and difficult to be integrated with other optical and electrical components. Optimally the phases from two facets should be in exact quadrature to each other to reduce the gain threshold and maximize the mode suppression [13]. To do so, phase-shifted grating structures have been extensively studied and applied in GaAs or InP-based DFB-LDs as an approach to improve the single longitudinal mode behavior [13]. By tuning the grating length [14], corrugation shapes [15] or using chirped gratings [16], lasers with enhanced performance have been reported in GaAs or InP-based DFB-LDs. Yet, such related research on III-nitride materials is still lacking.

It is also known that using semipolar orientated QWs instead of the conventional c-plane can boost the radiative efficiency, material gain and modulation speed due to the anisotropic strain that alleviates quantum-confined Stark effect and reduces the hole’s effective mass. [17] Most notably, the $({20{\overline 2}{\overline 1}})$ plane has been extensively studied and high-power blue LDs have been demonstrated on the semipolar orientation. Recently, a combination of thin p-GaN cladding layer and (ITO) has been shown in semipolar GaN laser diodes to reduce the optical loss and operating voltage [18] and, based on that system, a high-power etched surface grating DFB-LD has also been reported [19]. While there have been several experimental works on III-nitride DFB-LDs, their overall performance was still limited by a poor CW output power and low side-mode suppression ratio (SMSR) with no clear understanding or reason. To this day, no phase-shifted GaN DFB-LDs has been reported, to the best of our knowledge, and there is also a lack of investigation on the impact of grating orders on the laser performance. In this Letter, we propose a new embedded third-order phase-shifted design on semipolar GaN. By replacing the continuous etched grating with a phase-shifted embedded one, we achieved a very narrow spectra linewidth with a continuous-wave (CW) high-power output.

The DFB-LD structures presented here were grown by metalorganic chemical vapor deposition on free-standing bulk semipolar $({20{\overline 2}{\overline 1}})$ n-GaN substrates. The epitaxial layer included a double quantum well structure and symmetrical InGaN waveguides. On our reference sample with a first-order grating, a thin 250 nm p-GaN cladding was epitaxially grown on the top of the waveguide documented as in Ref. [18]. In the modified third-order grating structure, the thickness of the p-GaN cladding layer was reduced to 200 nm to increase the optical mode overlap to compensate for the reduced Fourier component of the third-order grating. Following the epitaxial growth, the samples were then processed into a DFB-LD structure with an embedded surface grating [Figs. 1(a) and 1(b)]. After the laser ridge was formed, a thin (${\sim}{10}\;{\rm nm}$) layer of ITO was first deposited on the p-GaN. During the deposition, the substrate wafer was kept at 50 degree C to ensure the smoothness of the surface [20]. Then the samples were spin-coated with 30 nm hydrogen silsesquioxane (HSQ) resist, and three types of grating patterns were written by e-beam lithography. On the reference sample, a first-order grating with a $\lambda /{4}$ shift in the center of the cavity was designed while, on the 200 nm p-GaN samples, third-order gratings with and without phase shifts were written on different ridges. The periods of first- and third-order grating were designed to be 90 and 270 nm with a 50% duty cycle, according to previous simulations [Figs. 2(a) and 2(b)]. After exposure, development and annealing, another 200 nm of ITO was deposited at an elevated (300 degree C) stage temperature. Subsequently, a thick Ti/Au probing pad was evaporated, ending up forming an embedded grating structure [Figs. 2(c) and 2(d)].

 figure: Fig. 1.

Fig. 1. (a) 3D schematic view of a DFB-LD with a phase-shifted embedded grating structure. (b) Cross-sectional view of the LD showing the first- and third-order grating structures with phase shifts, a p-GaN cladding layer, and an active region (in blue). The color area indicates the coupling between the active region and the grating. The line plot indicates the intensity of the fundamental mode, where the penetration into the gratings can be seen.

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 figure: Fig. 2.

Fig. 2. Top SEM views of a third-order (a) grating DFB-LD before the evaporation of the probing pad. (b) Bird’s eye SEM view of a fabricated LD with a 3 µm wide ridge. (c) Overview of the final device soldered on a copper heat sink. (d) Focused ion beam imaging of a third-order grating with a $\lambda /{4}$ shift in the center of the cavity.

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After fabrication, the substrates of the samples were then lapped down to 120 µm, followed by a dry etching process to remove the damaged layer and ${\rm n}$-side metallization for backside contact. Such samples were then backside soldered onto a copper heat sink. The lasers were tested under CW condition, and the light was measured by collecting the light emitted with a calibrated Si photodiode and fed into an ultra-high-resolution (${\lt}{1}\;{\rm pm}$) optical spectrum analyzer Advantest Q8347. To keep the testing thermally stable, a thermoelectric temperature controller was connected to the stage.

Typical spectral and light–current–voltage (L–I–V) characteristics of the fabricated DFB-LDs at room temperature are shown in Fig. 3(a). A marked impact was observed on both the spectra and light output characteristics resulting from the variations in the grating design. We found that by thinning the p-GaN cladding layer and increasing the grating order, the threshold current density increased from ${2.7}\;{{\rm kA/cm}^2}$ to ${3.8}\;{{\rm kA/cm}^2}$, and the threshold voltage decreased from 5.9 to 5.5 V. The 0.4 V voltage improvement in the third-order grating contributed from the thinner 200 nm p-cladding layer is consistent with previous reports on 250 nm p-cladding layer GaN laser diodes. The slope efficiency also slightly decreased from 0.9 to 0.81 W/A. In general, the operating voltage (${{\rm V}_{{\rm op}}}$) and output power of all the devices in this Letter have been significantly improved compared to the previous results on blue DFB-LDs with etched gratings [19], indicating the superiority of the embedded grating as an approach to protect the delicate p-GaN contact layer. On the other hand, a slight yet consistent difference on the threshold current was observed with and without a $\lambda /{4}$ shift. Furthermore, the optical output power rolled off at higher current densities due to self-heating.

 figure: Fig. 3.

Fig. 3. (a) CW L–I–V characteristics of 3 µm by 1800 µm DFB-LDs with different grating orders and phase-shifted lengths. (b) Far-field image of the laser; the inset figure shows the far-field horizontal light intensity at the distance of 6 mm to the laser facet. (c) Their spectra and SMSR at a current density of ${4.5}\;{{\rm kA/cm}^2}$.

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Single transverse mode lasing was observed in all three laser structures, as indicated by the far-field patterns and high-resolution transverse scanning with a multi-mode fiber [Fig. 3(b)]. More specifically, transverse linear scanning of the beam mode reveals a beam divergence half-angle of 9.6° and beam quality (${{\rm M}^2}$) of 1.35. After the initial L-I-V measurement, spectrum data were then collected and compared across different samples [Fig. 3(c)]. Lasers with a phase-shifted grating exhibited higher SMSR compared to the ones with a uniform grating as expected. Theoretically, without asymmetrical coating designs, two modes near the gain peak reach the threshold simultaneously resulting in a poor SMSR. We also found the third-order DFB-LDs had a higher SMSR than first-order ones. A high SMSR (32 dB) was observed on the third-order lasers, even at a relatively low current density (${4.5}\;{{\rm kA/cm}^2}$).

To have a better understanding of the performance variations with different DFB-LD grating designs, the dependence of the device luminescence characteristics with different cavity lengths was examined. To combine the mirror reflection of the uncoated facets and gratings, the total reflectivity can be calculated as in a three-mirror model, and expressed as

$$R = {R_g} + \frac{{\left({1 - R_g^2} \right)\!{R_m}}}{{1 + {R_{g{R_m}}}}},$$

where ${R_g}$ and ${R_m}$ are the reflectivity of the grating and facet, respectively [13]. Based on the coupled mode theory, at the Bragg wavelength, ${R_g}$ for a grating can be further estimated as

$${R_g} = \tanh\! \left({\kappa {L_g}} \right),$$

where ${L_g}$ is the length of the grating, i.e., the cavity length of a DFB-LD. The coupling constant ($\kappa$) is a crucial factor determining the magnitude of ${R_g}$ which can be estimated within the coupled mode theory [13] due to the small index change across the cavity ($\delta n\; \lt {0.1}\%$), as $\kappa = \frac{{2\delta n}}{\lambda}$, where $\delta n$ is the index difference across the grating, and $\lambda$ is the Bragg wavelength. It is also worth noting that the coupling constant derived from such a simple method might be an underestimation of the real coupling constant [21], and another experimental analysis to determine the coupling constant will be described.

The injection efficiency and the optical loss for each sample were extracted from the intercept and the slope using a cavity length method [13], as shown in Fig. 4(a). In such an extrapolation, we assume that the uncoated facet reflectivity of all three samples is 0.18, which was based on simulated modal refractive indices. From the extrapolation, we found that the internal loss increased from about 14 to ${19}\;{{\rm cm}^{- 1}}$ as we switched from first-order grating to the third-order grating with thinner p-GaN. Considering that the grating material HSQ itself has a very low absorption coefficient at visible wavelengths and should have no significant impact on the internal loss, we conclude that such a difference arises from the deeper optical mode penetration into the lossy ITO layer due to the reduced thickness of the p-GaN cladding layer. Such an observation agrees with the previous work that shows reducing the p-GaN cladding layer could lead to an efficiency degradation [18]. Such effects are likely to be more prominent here due to the low-temperature ITO deposition method used for the first 10 nm deposition. Simulated optical mode profile simulations further show that if the additional ${5}\;{{\rm cm}^{- 1}}$ loss originated entirely from ITO absorption, the material absorption coefficient would have to be ${3000}\;{{\rm cm}^{- 1}}$, rather high for ITO at this wavelength and implying that there is a significant room for improvement. Finite element method (FEM) simulations [Fig. 4(c)] and the refractive index difference method [13] further reveal that, even with a higher mode overlap from the thinner p-GaN cladding layer, the product of the coupling coefficient and cavity length of the third-order DFB-LD (${\sim}{0.65}$, for a 1800 µm cavity) is still lower than the reference first-order one (${\sim}{1.2}$). Such a difference in κ due to grating order difference allows us to analyze the impact of $\kappa L$ on the performance of the lasers. As $\kappa$ increases, the stopband of reflectance also widens, which often results in a worse mode suppression due to a flatter mirror loss curve [13] and can account for the SMSR differences we observed in Fig. 3(c). On the other hand, the increased reflectance, in turn, will cause a decrease in the total mirror loss and the laser threshold, which explains the threshold current difference in Fig. 3(a). Other than indirect estimation of the coupling coefficient from a simulation, previous studies also show that other methods such as a green function-based fitting of amplified spontaneous emission (ASE) spectrum could give a better insight [22]. Accurately characterizing the grating coefficient $\kappa$ directly from the device, however, remains difficult.

 figure: Fig. 4.

Fig. 4. (a) Inverse differential efficiency of different LDs as a function of cavity length. (b) Gain threshold versus injected current density for different DFB-LD designs. The dashed lines are the two parameter exponential fits. (c) FEM simulation of the mode profiles showing the fundamental mode penetrates into the HSQ layer for the third-order (left) and first-order (right) designs. Here we assume the refractive indices of ITO, HSQ, and GaN to be 2, 1.4, and 3.4, respectively. The κ values on the bottom represent the calculated coupling constants of the two structures.

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For that reason, to further understand the effect of $\kappa$ and phase shift on the spectrum and the threshold current variations, we compared the material gain of the different LDs as a function of the injected current, which can be readily obtained as the product of the injection efficiency and the threshold current density. When the material gain is plotted as a function of the injected current density, as in Fig. 4(b), the points can be fitted to the two parameter exponential curve through the approximation, $J = {J_{{\rm tr}}}\;{\rm exp}({{g}_{{\rm th}}}/{{g}_{\textit{oN}}})$, where ${J_{{\rm tr}}}$ is the transparency current density, and ${{g}_{0N}}$ is a material gain coefficient for the QWs, assuming the recombination at threshold is dominated by spontaneous recombination. Furthermore, the threshold modal gain can also be given as ${g_{{\rm th}}} = \frac{m}{{\Gamma}}({{\alpha _i} + {\alpha _m}}),$ where ${{\alpha _i}}$ and ${{\alpha _m}}$ are the internal and mirror loss, $m$ is the number of quantum wells, and $\Gamma$ is the optical mode confinement (1.04 % per quantum well) and can be obtained from a numerical mode solver simulation [23]. Using this approach and the extracted values from Fig. 3(a), a material gain coefficient of around ${2150}\;{{\rm cm}^{- 1}}$ per quantum well and ${J_{{\rm tr}}}$ of ${0.57}\;{{\rm kA/cm}^2}$ was extracted for both first-order (black) and third-order (red) LDs, which is comparable to what we previously observed in similar Fabry–Perot lasers [23]. Now assuming that the non-shifted grating LDs have the same gain–current relations as the phase-shifted ones, the reason for a slightly higher gain threshold can be expected to be a higher equivalent mirror loss $(\Gamma {g_{{\rm th}}} - {\alpha _i})L$ based on the equation defining gain threshold. From this approach, the total mirror loss difference due to the extra $\lambda /{4}$ shift can be extracted to be 0.4, which could be useful information to characterize the grating and coupling properties in future experiments. Based on such an extracted threshold difference for phased-shifted grating, the $\kappa L$ for the third-order grating can be calculated using the transmission spectrum method [13] to be ${\sim}{0.55}$, which is very close to what we estimated using the refractive index difference method (0.65).

 figure: Fig. 5.

Fig. 5. (a) Broad-range and (b) high-resolution CW spectrum of a phase-shifted third-order grating DFB-LD at a high current density. (c) SMSRs of different grating order DFB-LDs as a function of current density minus threshold current density.

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It is also well known that the mode suppression characteristics are sensitive to the laser design, and maintaining a high SMSR at high current densities is strongly desired in many applications. However, introducing a $\lambda /{4}$ phase-shifted region often increases the optical intensity around this region, creates a nonuniform carrier density distribution, and results in strong longitudinal spatial hole burning (SHB), leading to a degradation of SMSR [24,25]. A high $\kappa$ has been generally associated with SHB, especially in phase-shifted DFB-LDs. The SMSR performance of different order designs was tested under various current densities, and the results are shown in Fig. 5(c). As expected, the SMSR first slowly goes up as a result of current injection. For lasers with a first-order grating, the SMSR drops quickly at high current densities (${\gt}\!{7}\;{{\rm kA/cm}^2}$), while such a degradation is less severe when a high-order grating is used. Combining the results from Fig. 3(a) and Figs. 5(a) and 5(b), the phase-shifted third-order DFB-LD emits with a power of more than 300 mW, a SMSR of 35 dB, and a FWHM of less than 2 pm at ${8}\;{{\rm kA/cm}^2}$. Specifically, such results represent the blue monolithic semiconductor laser sources that emit 100 mW level single-mode continuous power output.

In summary, the high-performance blue DFB-LDs with HSQ embedded grating structure were presented in this Letter. Such universal laser designs are free from expensive and complicated regrowth or etched grating techniques and can be easily integrated with other photonic components. The results foreshadow an alternative approach to realize efficient and powerful visible single-frequency laser sources, which will be useful in many upcoming optics and quantum applications.

Funding

Solid State Lighting and Energy Electronics Center, University of California Santa Barbara.

Acknowledgment

The authors thank the UCSB nanofabrication facility for their assistance in the fabrication process.

Disclosures

The authors declare no conflicts of interest.

REFERENCES

1. J. Dai, X. Xie, and X. Zhang, Phys. Rev. Lett. 97, 103903 (2006). [CrossRef]  

2. V. Ménoret, R. Geiger, G. Stern, N. Zahzam, B. Battelier, A. Bresson, A. Landragin, and P. Bouyer, Opt. Lett. 36, 4128 (2011). [CrossRef]  

3. Y. Chi, D. Hsieh, C. Tsai, H. Chen, H. Kuo, and G. Lin, Opt. Express 23, 13051 (2015). [CrossRef]  

4. I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015). [CrossRef]  

5. P. Hammond and R. Hughes, Nat. Phys. Sci. 231, 59 (1971). [CrossRef]  

6. W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015). [CrossRef]  

7. C. Lin and C. Shank, Appl. Phys. Lett. 26, 389 (1975). [CrossRef]  

8. L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010). [CrossRef]  

9. Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015). [CrossRef]  

10. S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006). [CrossRef]  

11. J. Kang, H. Wenzel, E. Freier, V. Hoffmann, O. Brox, J. Fricke, L. Sulmoni, M. Matalla, C. Stölmacker, M. Kneissl, M. Weyers, and S. Einfeldt, Opt. Lett. 45, 935 (2020). [CrossRef]  

12. T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018). [CrossRef]  

13. L. Coldren, S. Corzine, and M. Mašnović, Diode Lasers and Photonic Integrated Circuits (Wiley, 2012).

14. M. Okai, N. Chinone, H. Taira, and T. Harada, IEEE Photonics Technol. Lett. 1, 200 (1989). [CrossRef]  

15. M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991). [CrossRef]  

16. P. Zhou and G. Lee, Appl. Phys. Lett. 58, 331 (1991). [CrossRef]  

17. W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009). [CrossRef]  

18. S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Express 26, 1564 (2018). [CrossRef]  

19. H. Zhang, D. Cohen, P. Chan, M. Wong, S. Mehari, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Lett. 44, 3106 (2019). [CrossRef]  

20. J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015). [CrossRef]  

21. T. Uusitalo, H. Virtanen, and M. Dumitrescu, Opt. Quantum Electron. 49, 206 (2017). [CrossRef]  

22. H. Wenzel, IEEE J. Sel. Top. Quantum Electron. 9, 865 (2003). [CrossRef]  

23. S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Jpn. J. Appl. Phys. 58, 020902 (2019). [CrossRef]  

24. K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991). [CrossRef]  

25. L. Ge, O. Malik, and H. Türeci, Nat. Photonics 8, 871 (2014). [CrossRef]  

References

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  • |
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  • |

  1. J. Dai, X. Xie, and X. Zhang, Phys. Rev. Lett. 97, 103903 (2006).
    [Crossref]
  2. V. Ménoret, R. Geiger, G. Stern, N. Zahzam, B. Battelier, A. Bresson, A. Landragin, and P. Bouyer, Opt. Lett. 36, 4128 (2011).
    [Crossref]
  3. Y. Chi, D. Hsieh, C. Tsai, H. Chen, H. Kuo, and G. Lin, Opt. Express 23, 13051 (2015).
    [Crossref]
  4. I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015).
    [Crossref]
  5. P. Hammond and R. Hughes, Nat. Phys. Sci. 231, 59 (1971).
    [Crossref]
  6. W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
    [Crossref]
  7. C. Lin and C. Shank, Appl. Phys. Lett. 26, 389 (1975).
    [Crossref]
  8. L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
    [Crossref]
  9. Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
    [Crossref]
  10. S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
    [Crossref]
  11. J. Kang, H. Wenzel, E. Freier, V. Hoffmann, O. Brox, J. Fricke, L. Sulmoni, M. Matalla, C. Stölmacker, M. Kneissl, M. Weyers, and S. Einfeldt, Opt. Lett. 45, 935 (2020).
    [Crossref]
  12. T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
    [Crossref]
  13. L. Coldren, S. Corzine, and M. Mašnović, Diode Lasers and Photonic Integrated Circuits (Wiley, 2012).
  14. M. Okai, N. Chinone, H. Taira, and T. Harada, IEEE Photonics Technol. Lett. 1, 200 (1989).
    [Crossref]
  15. M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991).
    [Crossref]
  16. P. Zhou and G. Lee, Appl. Phys. Lett. 58, 331 (1991).
    [Crossref]
  17. W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009).
    [Crossref]
  18. S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Express 26, 1564 (2018).
    [Crossref]
  19. H. Zhang, D. Cohen, P. Chan, M. Wong, S. Mehari, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Lett. 44, 3106 (2019).
    [Crossref]
  20. J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
    [Crossref]
  21. T. Uusitalo, H. Virtanen, and M. Dumitrescu, Opt. Quantum Electron. 49, 206 (2017).
    [Crossref]
  22. H. Wenzel, IEEE J. Sel. Top. Quantum Electron. 9, 865 (2003).
    [Crossref]
  23. S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Jpn. J. Appl. Phys. 58, 020902 (2019).
    [Crossref]
  24. K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
    [Crossref]
  25. L. Ge, O. Malik, and H. Türeci, Nat. Photonics 8, 871 (2014).
    [Crossref]

2020 (1)

2019 (2)

H. Zhang, D. Cohen, P. Chan, M. Wong, S. Mehari, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Lett. 44, 3106 (2019).
[Crossref]

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Jpn. J. Appl. Phys. 58, 020902 (2019).
[Crossref]

2018 (2)

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Express 26, 1564 (2018).
[Crossref]

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

2017 (1)

T. Uusitalo, H. Virtanen, and M. Dumitrescu, Opt. Quantum Electron. 49, 206 (2017).
[Crossref]

2015 (5)

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Y. Chi, D. Hsieh, C. Tsai, H. Chen, H. Kuo, and G. Lin, Opt. Express 23, 13051 (2015).
[Crossref]

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015).
[Crossref]

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

2014 (1)

L. Ge, O. Malik, and H. Türeci, Nat. Photonics 8, 871 (2014).
[Crossref]

2011 (1)

2010 (1)

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

2009 (1)

W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009).
[Crossref]

2006 (2)

J. Dai, X. Xie, and X. Zhang, Phys. Rev. Lett. 97, 103903 (2006).
[Crossref]

S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
[Crossref]

2003 (1)

H. Wenzel, IEEE J. Sel. Top. Quantum Electron. 9, 865 (2003).
[Crossref]

1991 (3)

K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
[Crossref]

M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991).
[Crossref]

P. Zhou and G. Lee, Appl. Phys. Lett. 58, 331 (1991).
[Crossref]

1989 (1)

M. Okai, N. Chinone, H. Taira, and T. Harada, IEEE Photonics Technol. Lett. 1, 200 (1989).
[Crossref]

1975 (1)

C. Lin and C. Shank, Appl. Phys. Lett. 26, 389 (1975).
[Crossref]

1971 (1)

P. Hammond and R. Hughes, Nat. Phys. Sci. 231, 59 (1971).
[Crossref]

Absil, P.

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

Baets, R.

K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
[Crossref]

Battelier, B.

Becerra, D.

Beere, H.

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Beltram, F.

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Borchert, B.

K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
[Crossref]

Bouyer, P.

Bresson, A.

Brox, O.

Chan, P.

Chen, H.

Chi, Y.

Chinone, N.

M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991).
[Crossref]

M. Okai, N. Chinone, H. Taira, and T. Harada, IEEE Photonics Technol. Lett. 1, 200 (1989).
[Crossref]

Cohen, D.

H. Zhang, D. Cohen, P. Chan, M. Wong, S. Mehari, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Lett. 44, 3106 (2019).
[Crossref]

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Jpn. J. Appl. Phys. 58, 020902 (2019).
[Crossref]

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Express 26, 1564 (2018).
[Crossref]

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Coldren, L.

L. Coldren, S. Corzine, and M. Mašnović, Diode Lasers and Photonic Integrated Circuits (Wiley, 2012).

Corzine, S.

L. Coldren, S. Corzine, and M. Mašnović, Diode Lasers and Photonic Integrated Circuits (Wiley, 2012).

Dai, J.

J. Dai, X. Xie, and X. Zhang, Phys. Rev. Lett. 97, 103903 (2006).
[Crossref]

Das, M.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015).
[Crossref]

David, K.

K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
[Crossref]

DenBaars, S.

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Jpn. J. Appl. Phys. 58, 020902 (2019).
[Crossref]

H. Zhang, D. Cohen, P. Chan, M. Wong, S. Mehari, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Lett. 44, 3106 (2019).
[Crossref]

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Express 26, 1564 (2018).
[Crossref]

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Dumitrescu, M.

T. Uusitalo, H. Virtanen, and M. Dumitrescu, Opt. Quantum Electron. 49, 206 (2017).
[Crossref]

Einfeldt, S.

Eliyahu, D.

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Faist, J.

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Farrell, R.

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Freier, E.

Fricke, J.

Ge, L.

L. Ge, O. Malik, and H. Türeci, Nat. Photonics 8, 871 (2014).
[Crossref]

Geiger, R.

Grzanka, S.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Guo, W.

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

Gwyn, S.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Hammond, P.

P. Hammond and R. Hughes, Nat. Phys. Sci. 231, 59 (1971).
[Crossref]

Hangleiter, A.

W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009).
[Crossref]

Harada, T.

M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991).
[Crossref]

M. Okai, N. Chinone, H. Taira, and T. Harada, IEEE Photonics Technol. Lett. 1, 200 (1989).
[Crossref]

Hoffmann, V.

Hsieh, D.

Hughes, R.

P. Hammond and R. Hughes, Nat. Phys. Sci. 231, 59 (1971).
[Crossref]

Ilchenko, V.

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Kang, J.

Katori, H.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015).
[Crossref]

Kelly, A.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Kneissl, M.

Kozaki, T.

S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
[Crossref]

Kuo, H.

Landragin, A.

Lee, G.

P. Zhou and G. Lee, Appl. Phys. Lett. 58, 331 (1991).
[Crossref]

Lee, S.

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Leonard, J.

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Leszczynski, M.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Liang, W.

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Lin, C.

C. Lin and C. Shank, Appl. Phys. Lett. 26, 389 (1975).
[Crossref]

Lin, G.

Mahler, L.

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Maleki, L.

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Malik, O.

L. Ge, O. Malik, and H. Türeci, Nat. Photonics 8, 871 (2014).
[Crossref]

Margalith, T.

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Mašnovic, M.

L. Coldren, S. Corzine, and M. Mašnović, Diode Lasers and Photonic Integrated Circuits (Wiley, 2012).

Masui, S.

S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
[Crossref]

Matalla, M.

Matsko, A.

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Mehari, S.

Ménoret, V.

Merckling, C.

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

Morthier, G.

K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
[Crossref]

Mukai, T.

S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
[Crossref]

Nagahama, S.

S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
[Crossref]

Najda, S.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Nakamura, S.

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Jpn. J. Appl. Phys. 58, 020902 (2019).
[Crossref]

H. Zhang, D. Cohen, P. Chan, M. Wong, S. Mehari, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Lett. 44, 3106 (2019).
[Crossref]

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Opt. Express 26, 1564 (2018).
[Crossref]

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Ohkubo, T.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015).
[Crossref]

Okai, M.

M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991).
[Crossref]

M. Okai, N. Chinone, H. Taira, and T. Harada, IEEE Photonics Technol. Lett. 1, 200 (1989).
[Crossref]

Pantouvaki, M.

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

Perlin, P.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Rafailov, E.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Ritchie, D.

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Savchenkov, A.

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Scheibenzuber, W.

W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009).
[Crossref]

Schwarz, U.

W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009).
[Crossref]

Seidel, D.

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Shank, C.

C. Lin and C. Shank, Appl. Phys. Lett. 26, 389 (1975).
[Crossref]

Slight, T.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Speck, J.

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Stanczyk, S.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Stern, G.

Stölmacker, C.

Sulmoni, L.

Taira, H.

M. Okai, N. Chinone, H. Taira, and T. Harada, IEEE Photonics Technol. Lett. 1, 200 (1989).
[Crossref]

Takamoto, M.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015).
[Crossref]

Tian, B.

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

Tredicucci, A.

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Tsai, C.

Tsuchiya, T.

M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991).
[Crossref]

Tsukayama, K.

S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
[Crossref]

Türeci, H.

L. Ge, O. Malik, and H. Türeci, Nat. Photonics 8, 871 (2014).
[Crossref]

Uomi, K.

M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991).
[Crossref]

Ushijima, I.

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015).
[Crossref]

Uusitalo, T.

T. Uusitalo, H. Virtanen, and M. Dumitrescu, Opt. Quantum Electron. 49, 206 (2017).
[Crossref]

Van Campenhout, J.

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

Van Thourhout, D.

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

Vankwikelberge, P.

K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
[Crossref]

Veprek, R.

W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009).
[Crossref]

Virtanen, H.

T. Uusitalo, H. Virtanen, and M. Dumitrescu, Opt. Quantum Electron. 49, 206 (2017).
[Crossref]

Walther, C.

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Wang, Z.

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

Watson, S.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Wenzel, H.

Weyers, M.

Wiersma, D.

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Witzigmann, B.

W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009).
[Crossref]

Wolf, T.

K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
[Crossref]

Wong, M.

Xie, X.

J. Dai, X. Xie, and X. Zhang, Phys. Rev. Lett. 97, 103903 (2006).
[Crossref]

Yadav, A.

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Yanamoto, T.

S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
[Crossref]

Yonkee, B.

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

Zahzam, N.

Zhang, H.

Zhang, X.

J. Dai, X. Xie, and X. Zhang, Phys. Rev. Lett. 97, 103903 (2006).
[Crossref]

Zhou, P.

P. Zhou and G. Lee, Appl. Phys. Lett. 58, 331 (1991).
[Crossref]

Appl. Phys. Express (1)

T. Slight, S. Stanczyk, S. Watson, A. Yadav, S. Grzanka, E. Rafailov, P. Perlin, S. Najda, M. Leszczyński, S. Gwyn, and A. Kelly, Appl. Phys. Express 11, 112701 (2018).
[Crossref]

Appl. Phys. Lett. (3)

P. Zhou and G. Lee, Appl. Phys. Lett. 58, 331 (1991).
[Crossref]

C. Lin and C. Shank, Appl. Phys. Lett. 26, 389 (1975).
[Crossref]

J. Leonard, D. Cohen, B. Yonkee, R. Farrell, T. Margalith, S. Lee, S. DenBaars, J. Speck, and S. Nakamura, Appl. Phys. Lett. 107, 011102 (2015).
[Crossref]

IEEE J. Quantum Electron. (2)

K. David, G. Morthier, P. Vankwikelberge, R. Baets, T. Wolf, and B. Borchert, IEEE J. Quantum Electron. 27, 1714 (1991).
[Crossref]

M. Okai, T. Tsuchiya, K. Uomi, N. Chinone, and T. Harada, IEEE J. Quantum Electron. 27, 1767 (1991).
[Crossref]

IEEE J. Sel. Top. Quantum Electron. (1)

H. Wenzel, IEEE J. Sel. Top. Quantum Electron. 9, 865 (2003).
[Crossref]

IEEE Photonics Technol. Lett. (1)

M. Okai, N. Chinone, H. Taira, and T. Harada, IEEE Photonics Technol. Lett. 1, 200 (1989).
[Crossref]

Jpn. J. Appl. Phys. (2)

S. Masui, K. Tsukayama, T. Yanamoto, T. Kozaki, S. Nagahama, and T. Mukai, Jpn. J. Appl. Phys. 45, L1223 (2006).
[Crossref]

S. Mehari, D. Cohen, D. Becerra, S. Nakamura, and S. DenBaars, Jpn. J. Appl. Phys. 58, 020902 (2019).
[Crossref]

Nat. Commun. (1)

W. Liang, V. Ilchenko, D. Eliyahu, A. Savchenkov, A. Matsko, D. Seidel, and L. Maleki, Nat. Commun. 6, 7371 (2015).
[Crossref]

Nat. Photonics (4)

L. Mahler, A. Tredicucci, F. Beltram, C. Walther, J. Faist, H. Beere, D. Ritchie, and D. Wiersma, Nat. Photonics 4, 165 (2010).
[Crossref]

Z. Wang, B. Tian, M. Pantouvaki, W. Guo, P. Absil, J. Van Campenhout, C. Merckling, and D. Van Thourhout, Nat. Photonics 9, 837 (2015).
[Crossref]

I. Ushijima, M. Takamoto, M. Das, T. Ohkubo, and H. Katori, Nat. Photonics 9, 185 (2015).
[Crossref]

L. Ge, O. Malik, and H. Türeci, Nat. Photonics 8, 871 (2014).
[Crossref]

Nat. Phys. Sci. (1)

P. Hammond and R. Hughes, Nat. Phys. Sci. 231, 59 (1971).
[Crossref]

Opt. Express (2)

Opt. Lett. (3)

Opt. Quantum Electron. (1)

T. Uusitalo, H. Virtanen, and M. Dumitrescu, Opt. Quantum Electron. 49, 206 (2017).
[Crossref]

Phys. Rev. B (1)

W. Scheibenzuber, U. Schwarz, R. Veprek, B. Witzigmann, and A. Hangleiter, Phys. Rev. B 80, 115320 (2009).
[Crossref]

Phys. Rev. Lett. (1)

J. Dai, X. Xie, and X. Zhang, Phys. Rev. Lett. 97, 103903 (2006).
[Crossref]

Other (1)

L. Coldren, S. Corzine, and M. Mašnović, Diode Lasers and Photonic Integrated Circuits (Wiley, 2012).

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Figures (5)

Fig. 1.
Fig. 1. (a) 3D schematic view of a DFB-LD with a phase-shifted embedded grating structure. (b) Cross-sectional view of the LD showing the first- and third-order grating structures with phase shifts, a p-GaN cladding layer, and an active region (in blue). The color area indicates the coupling between the active region and the grating. The line plot indicates the intensity of the fundamental mode, where the penetration into the gratings can be seen.
Fig. 2.
Fig. 2. Top SEM views of a third-order (a) grating DFB-LD before the evaporation of the probing pad. (b) Bird’s eye SEM view of a fabricated LD with a 3 µm wide ridge. (c) Overview of the final device soldered on a copper heat sink. (d) Focused ion beam imaging of a third-order grating with a $\lambda /{4}$ shift in the center of the cavity.
Fig. 3.
Fig. 3. (a) CW L–I–V characteristics of 3 µm by 1800 µm DFB-LDs with different grating orders and phase-shifted lengths. (b) Far-field image of the laser; the inset figure shows the far-field horizontal light intensity at the distance of 6 mm to the laser facet. (c) Their spectra and SMSR at a current density of ${4.5}\;{{\rm kA/cm}^2}$.
Fig. 4.
Fig. 4. (a) Inverse differential efficiency of different LDs as a function of cavity length. (b) Gain threshold versus injected current density for different DFB-LD designs. The dashed lines are the two parameter exponential fits. (c) FEM simulation of the mode profiles showing the fundamental mode penetrates into the HSQ layer for the third-order (left) and first-order (right) designs. Here we assume the refractive indices of ITO, HSQ, and GaN to be 2, 1.4, and 3.4, respectively. The κ values on the bottom represent the calculated coupling constants of the two structures.
Fig. 5.
Fig. 5. (a) Broad-range and (b) high-resolution CW spectrum of a phase-shifted third-order grating DFB-LD at a high current density. (c) SMSRs of different grating order DFB-LDs as a function of current density minus threshold current density.

Equations (2)

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R = R g + ( 1 R g 2 ) R m 1 + R g R m ,
R g = tanh ( κ L g ) ,

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