Nonlinear dynamics of semiconductor lasers with phase-conjugate feedback

Abstract

Semiconductor lasers are known to be extremely sensitive to external optical feedback. This paper considers the case in which the feedback is due to reflections from a phase-conjugate mirror, rather than from an ordinary mirror. Such phase-conjugate feedback (PCF) introduces novel features into the laser dynamics. A steady state in which the laser phase is locked to a fixed value can be reached when the amount of PCF is below a critical value. With increasing PCF, the steady state is destabilized and the laser output becomes chaotic following a period-doubling or a quasi-periodic route, depending on the amount of feedback. The effects of spontaneous-emission noise on the laser instabilities are studied by solving numerically a set of stochastic rate equations. Numerical simulations are used to study how the noise characteristics such as relative intensity noise, frequency noise, and the line shape are affected by the PCF.