Stability analysis of semiconductor laser with phase-conjugate feedback

The stability of the output power of a semiconductor laser with phase-conjugate feedback (PCF) is studied by numerical simulations based on the rate equations. We investigated the critical reflectivity at which the stable fixed output power evolves into periodic oscillation. As a result, we found that the critical reflectivity shows a periodic structure against the external cavity length and the stability is much enhanced at the periodic peak positions. The stability and dynamic behavior of a semiconductor laser with PCF are compared with those for conventional optical feedback. It is also found that the periods of the nearby peaks correspond to the frequency of the laser relaxation oscillation frequency and the stable peaks for the PCF are located at external lengths completely out of phase from those for the conventional feedback. Linear stability analysis using the rate equations is performed and the theoretical background for the stability is also given.