An exact analysis is presented of the steady-state stability of a semi
conductor laser subjected to feedback from a phase-conjugate mirror. R
educed stability occurs at low feedback whenever the effective externa
l delay time is an integer multiple of the relaxation oscillation peri
od. The role of a finite response time of the mirror is to enhance dra
stically the steady state stability. (C) 1998 Optical Society of Ameri
ca.