| Autor: |
Kumazaki, Naoki, Takagi, Yohei, Ishihara, Mikito, Kasahara, Kenichi, Sugiyama, Atsushi, Akikusa, Naota, Edamura, Tadataka |
| Zdroj: |
Japanese Journal of Applied Physics; Aug2008, Vol. 47 Issue 8R, p1-1, 1p |
| Abstrakt: |
We report the experimental linewidth enhancement factor (α-factor) results on mid-infrared InGaAs/InAlAs quantum cascade lasers (QCLs) obtained using the self-mixing method. The waveforms appearing under self-mixing conditions were different from those originally predicted, which assumed that the gain was symmetric around the gain peak and that α=0. The signs of the QCL α-factors were identified to be negative and asymmetric to the gain peak by using the nonsymmetrical mirror drive, and by comparing their wave patterns to those of conventional 1.55-µm laser diodes. The nonparabolicity of the subbands was a possible cause of the α-factor's asymmetry. The subbands are no longer parallel if the lasing energy is restricted by the nonparabolicity, which produces inhomogeneous broadening and an asymmetric optical gain spectrum with a long wavelength tail. Taking the nonparabolicity into account, we determined the QCL gain spectrum and the dependence of the α-factor on the spectral position relative to the gain peak. The dependence of the α-factor on detuning was in reasonable agreement with the calculation that accounts for the asymmetry in gain. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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