Recovery process of low-frequency fluctuations in laser diodes with external optical feedback

The recovery process of low-frequency fluctuations is experimentally investigated in a semiconductor laser with external optical feedback. Monotonic stepwise increase of the light output intensity is observed for various external cavity lengths. The time interval of each step corresponds to the round-trip time of the external cavity. Transitions between steps and dynamics within each step are analyzed. Experimental results are discussed with reference to the scenario of chaotic mode itinerancy. Statistical properties of time intervals between power dropout events are also discussed.