The effect of electronic feedback on semiconductor lasers

Negative electronic feedback (EFB) has a strong effect on the performance of a bistable laser diode amplifier and on injection-locked lasers. Negative EFB drastically reduces the switching-up input power level and the hysteresis in the input-output power characteristic and in the tuning curves of the bistable laser amplifier. Furthermore, negative EFB leads to a reduction in the time delay associated with optical switching in diode laser amplifiers. This provides a means of enhancing the versatility of the proposed system in some potential applications. For an injected-locked laser, negative EFB achieves a broadening in the locking bandwidth and its dynamically stable region.>