HIGH-SPEED 1.55 MU-M INGAAS/INGAASP MULTIQUANTUM-WELL LAMBDA/4-SHIFTED DFB LASERS

The high-speed modulation properties of 1.5 mu m multiquantum-well lambda/4-shifted DFB lasers are fully reviewed. In particular, the dependence of intrinsic dynamic proper?ies, such as relaxation oscillation frequency, nonlinear damping phenomenon, and spectral chirping under 10 Gbit/s direct modulation, on the number of quantum wells is systematically investigated and compared with those of bulk lasers. The results indicate that the dependence of the above three factors on the number of wells is clearly explained by the linear gain saturation of rite quantum-well lasers and that the optimum number of wells should be more than ten in order to increase the modulation bandwidth.