Abstract

Phase-conjugate optical feedback has been used recently to achieve linewidth narrowing in external cavity laser diodes as well as for improving the characteristics of laser diode arrays. It is well known that conventional mirror feedback can cause dramatic changes in the dynamical behaviour and noise properties of laser diodes. Of particular importance in such cases is the phase of the light returned to the laser after a round trip of the external cavity. Phase-conjugate mirrors, on the other hand, have the property of reversing the phase of light incident upon them. Consequently there is a zero round-trip phase change in an external cavity formed with a phase-conjugate mirror.

© 1994 IEEE