1 May 1990 Picosecond lasing dynamics in quantum well lasers
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Abstract
It is now well known that the differential gain is enhanced in quantum well (QW) lasers by a factor of four compared to conventional double-hetero structure (DH) lasers because of step-like density of states. This enhancement is effective for the ultra-short pulse generation as well as increased modulation bandwidth [1] In fact, an extremely short pulse as narrow as 1 .3psec is successfully achieved in the QW lasers as shown in Fig. 1 [2], On the other hand, in order to achieve efficient carrier injection, the QWs in the active layer should be appropriately coupled. However, this coupling reduces the quantumconfinement effects, which results in suppressing the enhancement of the differential gain. In this paper, we investigate the effects of the QW structure parameters, such as coupling effect and the number of quantum wells, on lasing dynamics in the gain-switched QW lasers by measuring both pulse forms and spectral dynamics through a streak camera. The results indicates that, in the coupled QW lasers, the shift of spectra occurs drastically to longer wavelength, which is due to the fact that the formation of the mini-band in the coupled QWs causes the bulk-like behavior in the picosecond lasing properties. We also observed strong dependence of both pulse forms and spectral dynamics on the number of the QWs. This dependence mainly results from the difference in the gain profile at the initial stage of the pulse formation due to the difference in the carrier concentration per well (cm2). In addition, the overflow effect of carriers outside of QWs also plays an important role for the QW laser with a smaller number of QWs. The results are also theoretically discussed.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Yasuhiko Arakawa, Tetsuomi Sogawa, "Picosecond lasing dynamics in quantum well lasers", Proc. SPIE 1216, Nonlinear Optical Materials and Devices for Photonic Switching, (1 May 1990); doi: 10.1117/12.18119; https://doi.org/10.1117/12.18119
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