Abstract

The sensitivity of semiconductor lasers to the external feedback is well known.¹,² Even a relatively small amount of feedback can destabilize the steady state and lead to nonlinear phenomena, such as coherence collapse, period doubling, and optical chaos. The phase of the feedback signal is important in the nonlinear dynamics. This dependence on the feedback phase can be eliminated if the feedback is produced by using a phase-conjugate mirror. This paper considers the effect of phase-conjugate feedback on semiconductor-laser dynamics by using the appropriate differential–difference rate equations. The steady-state solution of these equations shows that the effect of phase-conjugate feedback is to pin down the phase of the intracavity field. Another difference from the case of ordinary feedback is that the phase equation has only a single solution, so multiple external-cavity modes are never excited. The stability of the steady-state solutions is examined through a linear stability analysis. The results show that the steady state can become unstable not only through a Hopf bifurcation (similar to the case of ordinary feedback) but also through a fold bifurcation. The dynamic behavior beyond the linear stability analysis is studied by solving the differential–difference rate equations numerically.

© 1990 Optical Society of America