Subharmonic Microwave Modulation Stabilization of Tunable Photonic Microwave Generated by Period-One Nonlinear Dynamics of an Optically Injected Semiconductor Laser

We have proposed and experimentally demonstrated a novel approach to stabilize the photonic microwave generated by the period-one (P1) nonlinear dynamics of an optically injected semiconductor laser by introducing external subharmonic microwave modulation technique. External optical injection first drives a semiconductor laser into single sideband (SSB) P1 nonlinear dynamics whose frequency can be tuned by varying the optical injection strength, and then an external subharmonic microwave modulation is applied to the laser for stabilizing the frequency of the P1 oscillation. The experimental results show that after adopting 1/3 and 1/4 subharmonic microwave modulation, significant reduction up to more than three orders of magnitude of generated microwave linewidth can be achieved. Furthermore, we have analyzed the linewidth narrowing effects under subharmonic modulation with different powers and frequencies, and mapped the subharmonic microwave locking region in the parameter space of the power and frequency of the external subharmonic microwave.