## Room temperature continuous wave operation and controlled spontaneous emission in ultrasmall photonic crystal nanolaser

Optics Express, Vol. 15, Issue 12, pp. 7506-7514 (2007)

http://dx.doi.org/10.1364/OE.15.007506

Acrobat PDF (1155 KB)

### Abstract

Photonic crystal slab enables us to form an ultrasmall laser cavity with a modal volume close to the diffraction limit of light. However, the thermal resistance of such nanolasers, as high as 10^{6} K/W, has prevented continuous-wave operation at room temperature. The present paper reports on the first successful continuous-wave operation at room temperature for the smallest nanolaser reported to date, achieved through fabrication of a laser with a low threshold of 1.2 μW. Near-thresholdless lasing and spontaneous emission enhancement due to the Purcell effect are also demonstrated in a moderately low *Q* nanolaser, both of which are well explained by a detailed rate equation analysis.

© 2007 Optical Society of America

## 1. Introduction

## 2. Evaluation of room temperature CW lasing characteristics

### 2.1. Device fabrication

27. M. Fujita, A. Sugitatsu, T. Uesugi, and S. Noda, “Fabrication of indium phosphide compound photonic crystal by iodine/xenon inductively coupled plasma etching,” Jpn. J. Appl. Phys. **43**, L1400–1402 (2004). [CrossRef]

28. T. Ide, J. Hashimoto, K. Nozaki, E. Mizuta, and T. Baba, “InP etching by HI/Xe inductively coupled plasma for photonic-crystal device fabrication,” Jpn. J. Appl. Phys. **45**, L102–L104 (2006). [CrossRef]

_{2}-based processes. Figure 1 shows scanning electron micrographs of the H0 nanolaser thus fabricated. The sidewall roughness of holes is less than 10 nm. Figures 2(a) and 2(b) show the top view of the H0 nanolaser and the modal distribution (magnetic field normal to the slab,

*H*) calculated by the finite-difference time-domain (FDTD) method, respectively, which affords an accurate model of the fabricated device with slab thickness and index of 140 nm and 3.4, respectively. Theoretically, the monopole mode has an ultrasmall

_{z}*V*

_{m}of 0.019 μm

^{3}= 0.15(λ/

*n*)

^{3}and a high passive

*Q*of 1.3×10

^{5}. Figures 3(a) and 3(b) show the corresponding results for the H1 nanolaser. In this case, the innermost holes are 85% of the diameter of outer holes. This device supports orthogonal dipole modes with a larger

*V*

_{m}of 0.028 μm

^{3}= 0.28(λ/

*n*)

^{3}and a lower

*Q*of 1.1×10

^{3}.

### 2.1. Measurement of lasing characteristics

*P*

_{eff}) was evaluated from the absorption efficiency of irradiated light in the slab (22%) [29

29. K. Nozaki, A. Nakagawa, D. Sano, and T. Baba, “Ultralow threshold and singlemode lasing in microgear lasers and its fusion with quasiperiodic photonic crystals,” IEEE J. Sel. Top. Quantum Electron. **9**, 1355–1360 (2003). [CrossRef]

*P*

_{eff}= 1.2 μW at RT (293 K), above which the single-mode spectrum of the monopole mode reaches a 40 dB peak over background and a resolution limit spectral width (Δλ) of 0.06 nm. At 0.8 times the threshold (the estimated transparent condition), Δλ is 0.08 nm and the corresponding

*Q*is 20,000. This is a reasonable value considering the theoretical passive

*Q*and the free carrier absorption in the active region, although the H0 nanocavity theoretically has a higher

*Q*of over 10

^{5}. On the other hand, the H1 nanolaser exhibits dull kink at around

*P*

_{eff}= 2.4 μW. The double peak spectrum of dipole modes reaches a 25 dB peak near RT (263 K). In the transparent state, Δλ is estimated to be 1.0 nm and the corresponding

*Q*is 1,500, in close agreement with the theoretical value. As shown in Figs. 2(d) and 3(d), the logarithmic plots of the modal intensity characteristics clearly show that the H1 nanolaser exhibits near-thresholdless behavior, even though the weaker Purcell effect than that in H0 nanolaser would be expected from the larger modal volume.

## 3. Time-resolved measurement of emission decay

*F*) are calculated to be 25 and 13 for the H0 and H1 nanolasers, respectively, assuming typical parameters for the GaInAsP QW wafers at RT (

*a*

_{p}= 0.4,

*n*= 3.4, and Δλ= 8.8 nm for a homogeneous broadening of 4.3 meV) [17

17. T. Baba and D. Sano, “Low threshold lasing and Purcell effect in microdisk lasers at room temperature,” IEEE J. Sel. Top. Quantum Electron. **9**, 1340–1346 (2003). [CrossRef]

*Q*is not necessarily important for achieving thresholdless operation.

## 4. Theoretical fitting of Purcell factor

*N*(

*x*,

*y*,

*z*;

*t*) and photon density of the laser mode

*S*(

*t*) with respect to positions

*x*,

*y*,

*z*and time

*t*, as given by [30

30. K. Nozaki and T. Baba, “Carrier and photon analyses of photonic microlasers by two-dimensional rate equations,” IEEE J. Sel. Area. Commun. **23**, 1411–1417 (2005). [CrossRef]

*P*

_{pump}is the pump power density,

*ħ*ω

_{pump}is the pump energy,

*G*(

*N*) is the gain coefficient,

*C*is the spontaneous emission coupling factor into the laser mode when the Purcell effect is not counted,

*B*is the radiative recombination coefficient,

*C*

_{A}is the Auger recombination coefficient,

*D*is the carrier diffusion constant, τ

_{ph}is the photon lifetime determined by the passive cavity

*Q*and the free carrier absorption loss, and

*υ*

_{s}is the surface recombination velocity.

*E*is the electric field distribution of the laser mode, which is normalized such that ∫∫∫

*n*

^{2}|

*E*|

^{2}d

*x*d

*y*d

*z*= [

*n*

^{2}|

*E*|

^{2}]

_{max}

*V*

_{m}= 1. Further details of these equations were referred to Ref. 30, except for the third term on the right side of Eq. (1). This term introduced in the present paper expresses the controlled SpE; the SpE term for the laser mode is weighted by

*Fn*

^{2}|

*E*|

^{2}

*V*

_{m}. When

*FC*≫ 1, the (1-

*C*) term in parenthesis is negligible for the laser mode, and the equations become dependent only on

*FC*. The theoretical results shown in Fig. 5 are calculated with typical parameters for the wafer [31

31. M. Fujita, A. Sakai, and T. Baba, “Ultra-small and ultra-low threshold microdisk injection laser - design, fabrication, lasing characteristics and spontaneous emission factor,” IEEE J. Sel. Top. Quantum Electron. **5**, 673–681 (1999). [CrossRef]

*Q*for each laser, and the short pulse pumping condition used in the time-resolved measurement. Fitting the theoretical characteristics to the experimental plots suggests

*FC*values of 10 and 7 for the H0 and H1 nanolasers, respectively. For the dipole mode of the H1 nanolaser,

*C*is calculated to be 0.4 [32

32. J. Vučkovič, O. Painter, Y. Xu, A. Yariv, and A. Scherer, “Finite-difference time-domain calculation of the spontaneous emission coupling factor in optical microcavities,” IEEE J. Quantum Electron. **35**, 1168–1175 (1999). [CrossRef]

*FC*can be well explained by a

*C*value of 0.4–0.5 and the theoretical

*F*values of 25 and 13. If the (1-

*C*) term is not neglected, the SpE coupling factor enhanced by the Purcell effect can be expressed as

*C*′ =

*FCn*

^{2}|

*E*|

^{2}

*V*

_{m}/(

*FCn*

^{2}|

*E*|

^{2}

*V*

_{m}+1-

*C*) for a local dipole and averaged as

*C*′ =

*FC*/(

*FC*+1-

*C*) for dipoles distributed over the modal area in the QW. For the experimental results, averaged

*C*′ of 0.94 and 0.92 are estimated for the H0 and H1 nanolasers, respectively. However, if the two dipole modes in the H1 nanolaser have the same

*F*, averaged

*C*′ would be half of this value.

*C*′, the SpE intensity below the threshold is more than two orders of magnitude lower than the ideal thresholdless level. One reason for this is the short pulse pumping in the time-resolved measurement, which leads a lower carrier density [33], longer SpE lifetime and higher carrier losses. Therefore, the intensity becomes much higher in the CW experiment, as shown in Figs. 2(d) and 3 (d). But still the intensity is 1 – 2 orders lower than the thresholdless level. This is due to various carrier losses, as explained in the next section.

## 5. Discussion

### 5.1. Origin of the carrier losses

*Q*are explained by the rate equation analysis. Figure 6(a) shows the laser characteristics calculated for the H0 nanolaser under CW condition. Parameters used for (A) – (D) are summarized in Table I. (A) shows the result for typical parameters of

*υ*

_{s}= 2 × 10

^{4}cm/s,

*D*= 2 cm

^{2}/s, and

*FC*= 10 (

*F*= 25,

*C*= 0.4). The SpE intensity is attenuated two orders lower than the thresholdless level by surface recombination, carrier diffusion, and nonlaser mode emission. When the surface recombination and carrier diffusion are neglected by assuming

*υ*

_{s}= 0 cm/s and

*D*= 0 cm

^{2}/s, the SpE intensity becomes 30 times higher, as shown in (B) and (C). The remaining carrier loss is the nonlaser modes, which originates from the assumption

*C*= 0.4. (When the surface recombination and carrier diffusion are neglected, (1-

*C*) term in Eq. (1) cannot be ignored.) Actually, (D) calculated for

*C*= 1 well traces the ideal thresholdless line. But particularly large attenuation of the SpE in (C) is caused by a photon recycling process. Figure 6(b) shows the schematic showing the carrier and photon behaviors in the cavity. In a high-

*Q*nanocavity, emitted photons coupled to the laser mode are strongly reabsorbed below the transparent condition due to the long photon lifetime. (It is different from the so-called strong coupling regime of electron and photon, because the electronic coherent state is hardly maintained within the photon lifetime in the QW active region at RT.) The recycled carriers are partly redistributed to nonlaser mode emission, which quickly escapes from the cavity, or wasted by nonradiative recombinations. This recycling process severely accelerates carrier losses and reduces the SpE intensity.

### 5.2. Discussion for effective spontaneous emission enhancement

34. H. Ichikawa, K. Inoshita, and T. Baba, “Reduction in surface recombination of GaInAsP/InP micro-columns by CH_{4} plasma irradiation,” Appl. Phys. Lett., **78**, 2119–2121 (2001). [CrossRef]

*F*. For a large

*F*, the SpE rate for the laser mode becomes higher than the nonradiative recombination rate, and the spatial hole burning of carriers formed by the intensified mode suppresses the carrier diffusion to outside of the cavity. In addition, the coupling of SpE to nonlaser modes is relatively suppressed. As a result, the SpE intensity is enhanced almost in proportional to

*F*, as shown in Fig. 7(a). However,

*F*in this experiment cannot be enhanced by the cavity

*Q*but constrained by the homogeneous broadening. Therefore, a significant enhancement is not expected without employing another material with a narrower homogeneous broadening. The third one is the optimization of the cavity

*Q*. Figure 7(b) shows the intensity characteristics calculated against different

*Q*s. As mentioned above, a high

*Q*accelerates carrier losses through the photon recycling process. The SpE intensity is clearly enhanced for lower

*Q*, even though the threshold also increases.

## 6. Conclusion

*Q*factor of 20,000 and an effective lasing threshold of just 1.2 μW. The enhanced SpE rate due to the Purcell effect was evaluated carefully through time-domain measurements. The product of the Purcell factor and the SpE coupling factor,

*FC*, was estimated to be 10 for this nanolaser. The observed characteristics were well explained by a detailed rate equation analysis, with the results indicating that carrier losses and photon recycling process in a device with unnecessarily high

*Q*degrade the SpE intensity below the lasing threshold. Actually, near-thresholdless operation was observed in a device with a low

*Q*of 1500. Thus, a high

*Q*is desirable for low threshold laser operation, while a moderately low

*Q*is effective when high efficiency modal emission below threshold is particularly expected in such applications as a single photon emitter.

## Acknowledgment

## References and links

1. | T. H. Maiman, “Stimulated optical radiation in ruby,” Nature |

2. | I. Hayashi, M. B. Panish, P. W. Foy, and S. Sumski, “Junction lasers which operate continuously at room temperature,” Appl. Phys. Lett. |

3. | K. Iga, F. Koyama, and S. Kinoshita, “Surface emitting semiconductor lasers,” IEEE J. Quantum Electron, |

4. | J. L. Jewell, J. P. Harbison, A. Scherer, Y. H. Lee, and L. T. Florez, “Vertical-cavity surface emitting lasers: design, growth, fabrication, characterization,” IEEE J. Quantum Electron. |

5. | S. L. McCall, A. F. J. Levi, R. E. Slusher, S. J. Pearton, and R. A. Logan, “Whispering gallery mode microdisk lasers,” Appl. Phys. Lett. |

6. | O. Painter, R. K. Lee, A. Scherer, A. Yariv, J. D. O’Brien, D. D. Dapkus, and I. Kim, “Two dimensional photonic band-gap defect mode laser,” Science |

7. | E. M. Purcell, “Spontaneous emission probabilities at radio frequencies,” Phys. Rev. |

8. | T. Kobayashi, Y. Morimoto, and T. Sueta, “Closed microcavity laser,” Nat. Top. Meet. Rad. Sci. RS85-06 (1985). |

9. | E. Yablonovitch and T. J. Gmitter, “Inhibited spontaneous emission in solid state physics and electronics,” Phys. Rev. Lett. |

10. | Y. Yamamoto, ed., “ |

11. | H. Yokoyama and K. Ujihara, eds., “ |

12. | T. Baba, “Photonic crystals and microdisk cavities based on GaInAsP-InP system,” IEEE J. Sel. Top. Quantum Electron. |

13. | J. M. Gérard and B. Gayral, “Strong purcell effect for InAs quantum boxes in three-dimensional solid-state microcavities,” J. Lightwave Technol. |

14. | M. Loncâr, T. Yoshie, A. Scherer, P. Gogna, and Y. Qiu, “Low-threshold photonic crystal laser,” Appl. Phys. Lett. |

15. | H. Y. Ryu, M. Notomi, E. Kuramochi, and T. Segawa, “Large spontaneous emission factor (>0.1) in the photonic crystal monopole-mode laser,” Appl. Phys. Lett. |

16. | T. Baba, D. Sano, K. Nozaki, K. Inoshita, Y. Kuroki, and F. Koyama, “Observation of fast spontaneous emission decay in GaInAsP photonic crystal point defect nanocavity at room temperature,” Appl. Phys. Lett. |

17. | T. Baba and D. Sano, “Low threshold lasing and Purcell effect in microdisk lasers at room temperature,” IEEE J. Sel. Top. Quantum Electron. |

18. | R. Coccioli, M. Boroditsky, K.W. Kim, Y. Rahmat-Samii, and E. Yablonovitch, “Smallest possible electromagnetic mode volume in a dielectric cavity,” IEE Proc.-Optoelectron. |

19. | Z. Zhang and M. Qiu, “Small-volume waveguide-section high |

20. | K. Nozaki, T. Ide, J. Hashimoto, W. H. Zheng, and T. Baba, “Photonic crystal point shift nanolaser with ultimate small modal volume,” Electron. Lett. |

21. | K. Nozaki and T. Baba, “Laser characteristics with ultimate-small modal volume in photonic crystal slab point-shift nanolasers,” Appl. Phys. Lett. |

22. | K. Inoshita and T. Baba, “Fabrication of GaInAsP/InP photonic crystal lasers by ICP etching and control of resonant mode in point and line composite defects,” IEEE J. Sel. Top. Quantum Electron. |

23. | J. K. Hwang, H. Y. Ryu, D. S. Song, I. Y. Han, H. K. Park, D. H. Jang, and Y. H. Lee, “Continuous room-temperature operation of optically pumped two-dimensional photonic crystal lasers at 1.6 μm,” Photon. Tech. Lett. |

24. | M. Nomura, S. Iwamoto, K. Watanabe, N. Kumagai, Y. Nakata, S. Ishida, and Y. Arakawa, “Room temperature continuous-wave lasing in photonic crystal nanocavity,” Opt. Exp. |

25. | D. Englund, D. Fattal, E. Waks, G. Solomon, B. Zhang, T. Nakaoka, Y. Arakawa, Y. Yamamoto, and J. Vučković, “Controlling the spontaneous emission rate of single quantum dots in a two-dimensional photonic crystal,” Phys. Rev. Lett. |

26. | W. H. Chang, W. Y. Chen, H. S. Chang, T. P. Hsieh, J. I. Chyi, and T. M. Hsu, “Efficient single-photon sources based on low-density quantum dots in photonic-crystal nanocavities,” Phys. Rev. Lett. |

27. | M. Fujita, A. Sugitatsu, T. Uesugi, and S. Noda, “Fabrication of indium phosphide compound photonic crystal by iodine/xenon inductively coupled plasma etching,” Jpn. J. Appl. Phys. |

28. | T. Ide, J. Hashimoto, K. Nozaki, E. Mizuta, and T. Baba, “InP etching by HI/Xe inductively coupled plasma for photonic-crystal device fabrication,” Jpn. J. Appl. Phys. |

29. | K. Nozaki, A. Nakagawa, D. Sano, and T. Baba, “Ultralow threshold and singlemode lasing in microgear lasers and its fusion with quasiperiodic photonic crystals,” IEEE J. Sel. Top. Quantum Electron. |

30. | K. Nozaki and T. Baba, “Carrier and photon analyses of photonic microlasers by two-dimensional rate equations,” IEEE J. Sel. Area. Commun. |

31. | M. Fujita, A. Sakai, and T. Baba, “Ultra-small and ultra-low threshold microdisk injection laser - design, fabrication, lasing characteristics and spontaneous emission factor,” IEEE J. Sel. Top. Quantum Electron. |

32. | J. Vučkovič, O. Painter, Y. Xu, A. Yariv, and A. Scherer, “Finite-difference time-domain calculation of the spontaneous emission coupling factor in optical microcavities,” IEEE J. Quantum Electron. |

33. | Y. Suematsu and S. Akiba, “High-speed pulse modulation of injection lasers at non-bias condition,” Trans. IECE of Japan |

34. | H. Ichikawa, K. Inoshita, and T. Baba, “Reduction in surface recombination of GaInAsP/InP micro-columns by CH |

**OCIS Codes**

(140.5960) Lasers and laser optics : Semiconductor lasers

(230.3990) Optical devices : Micro-optical devices

**ToC Category:**

Lasers and Laser Optics

**History**

Original Manuscript: April 19, 2007

Revised Manuscript: May 28, 2007

Manuscript Accepted: May 28, 2007

Published: June 4, 2007

**Citation**

Kengo Nozaki, Shota Kita, and Toshihiko Baba, "Room temperature continuous wave operation and controlled spontaneous emission in ultrasmall photonic crystal nanolaser," Opt. Express **15**, 7506-7514 (2007)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-15-12-7506

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### References

- T. H. Maiman, "Stimulated optical radiation in ruby," Nature 187, 493−494 (1960). [CrossRef]
- I. Hayashi, M. B. Panish, P. W. Foy and S. Sumski, "Junction lasers which operate continuously at room temperature," Appl. Phys. Lett. 17, 109−111 (1970). [CrossRef]
- K. Iga, F. Koyama and S. Kinoshita, "Surface emitting semiconductor lasers," IEEE J. Quantum Electron., 24, 1845−1855 (1988). [CrossRef]
- J. L. Jewell, J. P. Harbison, A. Scherer, Y. H. Lee and L. T. Florez, "Vertical-cavity surface emitting lasers: design, growth, fabrication, characterization," IEEE J. Quantum Electron. 27, 1332-1347 (1991). [CrossRef]
- S. L. McCall, A. F. J. Levi, R. E. Slusher, S. J. Pearton and R. A. Logan, "Whispering gallery mode microdisk lasers," Appl. Phys. Lett. 60, 289−291 (1992). [CrossRef]
- O. Painter, R. K. Lee, A. Scherer, A. Yariv, J. D. O’Brien, D. D. Dapkus, and I. Kim, "Two dimensional photonic band-gap defect mode laser," Science 284, 1819-1821 (1999). [CrossRef] [PubMed]
- E. M. Purcell, "Spontaneous emission probabilities at radio frequencies," Phys. Rev. 69, 681 (1946).
- T. Kobayashi, Y. Morimoto and T. Sueta, "Closed microcavity laser," Nat. Top. Meet. Rad. Sci. RS85-06 (1985).
- E. Yablonovitch and T. J. Gmitter, "Inhibited spontaneous emission in solid state physics and electronics," Phys. Rev. Lett. 58, 2059−2062 (1987). [CrossRef] [PubMed]
- Y. Yamamoto, ed., "Coherence, Amplification, and Quantum effects in Semiconductor Lasers," (John Wiley & Sons, New York, 1991).
- H. Yokoyama and K. Ujihara, eds., "Spontaneous Emission and Laser Oscillation in Microcavities," (CRC Press, New York, 1995).
- T. Baba, "Photonic crystals and microdisk cavities based on GaInAsP-InP system," IEEE J. Sel. Top. Quantum Electron. 3, 808-830 (1997). [CrossRef]
- J. M. Gérard and B. Gayral, "Strong purcell effect for InAs quantum boxes in three-dimensional solid-state microcavities," J. Lightwave Technol. 17, 2089-2095 (1999). [CrossRef]
- M. Loncâr, T. Yoshie, A. Scherer, P. Gogna and Y. Qiu, "Low-threshold photonic crystal laser," Appl. Phys. Lett. 81, 2680-2682 (2002). [CrossRef]
- H. Y. Ryu, M. Notomi, E. Kuramochi, and T. Segawa, "Large spontaneous emission factor (>0.1) in the photonic crystal monopole-mode laser," Appl. Phys. Lett. 84, 1067-1069 (2004). [CrossRef]
- T. Baba, D. Sano, K. Nozaki, K. Inoshita, Y. Kuroki and F. Koyama, "Observation of fast spontaneous emission decay in GaInAsP photonic crystal point defect nanocavity at room temperature," Appl. Phys. Lett. 85, 3989−3991 (2004). [CrossRef]
- T. Baba and D. Sano, "Low threshold lasing and Purcell effect in microdisk lasers at room temperature," IEEE J. Sel. Top. Quantum Electron. 9, 1340-1346 (2003). [CrossRef]
- R. Coccioli, M. Boroditsky, K.W. Kim, Y. Rahmat-Samii and E. Yablonovitch, "Smallest possible electromagnetic mode volume in a dielectric cavity," IEE Proc.-Optoelectron. 145, 391−397 (1998). [CrossRef]
- Z. Zhang and M. Qiu, "Small-volume waveguide-section high Q microcavities in 2D photonic crystal slabs," Opt. Exp. 12, 3988−3995 (2004). [CrossRef]
- K. Nozaki, T. Ide, J. Hashimoto, W. H. Zheng and T. Baba, "Photonic crystal point shift nanolaser with ultimate small modal volume," Electron. Lett. 41, 843−845 (2005). [CrossRef]
- K. Nozaki and T. Baba, "Laser characteristics with ultimate-small modal volume in photonic crystal slab point-shift nanolasers," Appl. Phys. Lett. 88, 211101 (2006). [CrossRef]
- K. Inoshita and T. Baba, "Fabrication of GaInAsP/InP photonic crystal lasers by ICP etching and control of resonant mode in point and line composite defects," IEEE J. Sel. Top. Quantum Electron. 9, 1347−1354 (2003). [CrossRef]
- J. K. Hwang, H. Y. Ryu, D. S. Song, I. Y. Han, H. K. Park, D. H. Jang and Y. H. Lee, "Continuous room-temperature operation of optically pumped two-dimensional photonic crystal lasers at 1.6 μm," Photon. Tech. Lett. 12, 1295−1297 (2000). [CrossRef]
- M. Nomura, S. Iwamoto, K. Watanabe, N. Kumagai, Y. Nakata, S. Ishida, and Y. Arakawa, "Room temperature continuous-wave lasing in photonic crystal nanocavity," Opt. Express 14, 6308−6315 (2006). [CrossRef]
- D. Englund, D. Fattal, E. Waks, G. Solomon, B. Zhang, T. Nakaoka, Y. Arakawa, Y. Yamamoto and J. Vuèkoviæ, "Controlling the spontaneous emission rate of single quantum dots in a two-dimensional photonic crystal," Phys. Rev. Lett. 95, 013904 (2005). [CrossRef] [PubMed]
- W. H. Chang, W. Y. Chen, H. S. Chang, T. P. Hsieh, J. I. Chyi and T. M. Hsu, "Efficient single-photon sources based on low-density quantum dots in photonic-crystal nanocavities," Phys. Rev. Lett. 96, 117401 (2006). [CrossRef] [PubMed]
- M. Fujita, A. Sugitatsu, T. Uesugi and S. Noda, "Fabrication of indium phosphide compound photonic crystal by iodine/xenon inductively coupled plasma etching," Jpn. J. Appl. Phys. 43, L1400−1402 (2004). [CrossRef]
- T. Ide, J. Hashimoto, K. Nozaki, E. Mizuta and T. Baba, "InP etching by HI/Xe inductively coupled plasma for photonic-crystal device fabrication," Jpn. J. Appl. Phys. 45, L102−L104 (2006). [CrossRef]
- K. Nozaki, A. Nakagawa, D. Sano and T. Baba, "Ultralow threshold and singlemode lasing in microgear lasers and its fusion with quasiperiodic photonic crystals," IEEE J. Sel. Top. Quantum Electron. 9, 1355−1360 (2003). [CrossRef]
- K. Nozaki and T. Baba, "Carrier and photon analyses of photonic microlasers by two-dimensional rate equations," IEEE J. Sel. Area. Commun. 23, 1411−1417 (2005). [CrossRef]
- M. Fujita, A. Sakai and T. Baba, "Ultra-small and ultra-low threshold microdisk injection laser - design, fabrication, lasing characteristics and spontaneous emission factor," IEEE J. Sel. Top. Quantum Electron. 5, 673−681 (1999). [CrossRef]
- J. Vuèkoviè, O. Painter, Y. Xu, A. Yariv and A. Scherer, "Finite-difference time-domain calculation of the spontaneous emission coupling factor in optical microcavities," IEEE J. Quantum Electron. 35, 1168−1175 (1999). [CrossRef]
- Y. Suematsu and S. Akiba, "High-speed pulse modulation of injection lasers at non-bias condition," Trans. IECE of Japan 59, 1−8 (1976).
- H. Ichikawa, K. Inoshita and T. Baba, "Reduction in surface recombination of GaInAsP/InP micro-columns by CH4 plasma irradiation," Appl. Phys. Lett., 78, 2119−2121 (2001). [CrossRef]

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