Effect of phase-conjugate feedback on semiconductor laser dynamics

The effect of phase-conjugate feedback on the dynamic response of semiconductor lasers is studied by using a rate-equation approach. The steady state exists only for certain well-defined values of the phase of the intracavity optical field. Depending on the amount of phase-conjugate feedback, the steady state becomes unstable through two independent instabilities, referred to as fold and Hopf instabilities. The fold instability is due solely to the phase-conjugate nature of the feedback and does not occur in the case of normal feedback. In the instability region, the laser output is found to become chaotic by following a period-doubling or quasi-periodic route to chaos, depending on the amount of feedback.