Semiconductor lasers under orthogonal frequency-dependent optical feedback: experiments and theory

This paper presents experimental setup to study the influence of frequency-selective orthogonal, polarization-rotated feedback, of a semiconductor laser by placing a frequency-sensitive filter (Cs-vapor cell) in the way of the feedback beam to spectrally modulate the feedback power. Two different emission frequencies with almost the same output power were observed (less than 1% amplitude modulation was observed). This frequency bistability can have potential applications for all-optical logic gates and optical digital information technologies. Numerical simulation model that includes thermal and gain-saturation effects correctly reproducing the previously observed dynamics was also studied.