Dynamic modeling of semiconductor laser under self-optical feedback: Theory and experiment

Abstract

The effects of optical feedback (OF) in semiconductor lasers (SL) have been studied extensively. Recently, interest in this subject has continuously intensified because of the growing emphasis on optical communication systems, with their requirements for stable, narrow linewidth sources. There are many different effects of semiconductor lasers subjected to external reflections. OF was found to induce mode hopping, coherence collapse, and mode partition noise in the SL spectrum, which could cause noise fluctuations in the SL power output. OF is also highly effective in linewidth reduction or broadening depending upon the amount of feedback. Here, we investigate the effect of optical feedback on the relaxation oscillation of semiconductor lasers. Relaxation oscillations (RO) are important when it is desired to modulate the SL at higher frequencies or at frequencies near the device oscillation frequency. Depending upon the system application some modulation schemes may be optimized. However, in straight AM modulation, distortions can still occur at frequencies near resonance.