State Switching Phase-Space Trajectory of a Semiconductor Laser with Optical Feedback

The switching dynamics between a stable state and a period-one (P1) state is investigated in a semiconductor laser with conventional optical feedback. The switching dynamics requires feedback with a long round-trip delay time. Experimentally, state switching is observed with the period corresponding to the round-trip time and a microwave oscillation frequency at around the relaxation resonance frequency of the laser. Numerically, cases with different round-trip times are compared for presenting a clear route to state switching. The phase-space trajectory of the state switching is shown as comprised of a dwelling in an external cavity mode during the stable emission and a periodic cycling during the P1 oscillation.