Linewidth study of 40-GHz passively mode-locked multimode semiconductor lasers

Passively mode-locked (PML) lasers have recently been investigated for pulse signal generation as they exhibit a periodic time variation of their output emission under continuous wave bias conditions. These devices allow a cost effective solution for pulse waveform signals generation at 40 GHz as they do not require any direct or external modulation. There are several types of configurations for edge emitting PML lasers. Among the most important are those based on gain-coupled distributed feedback (DFB) lasers [1], distributed Bragg reflector (DBR) lasers [2] and Fabry-Pérot (FP) cavities [3].