Nonlinear Optics and Nonlinear Dynamics in Semiconductor Lasers Subject to External Optical Injection

摘要

This Phase II SBIR effort investigates novel output characteristics of semiconductor lasers that can be induced by external optical injection. Specific interest is in characteristics relevant to the control of microwave and millimeter-wave electronics through enhanced modulation characteristics, characterization of vertical cavity surface emitting laser (VCSEL) arrays, and analysis of chaotic dynamics that can be induced by optical injection. Under external optical injection, all semiconductor lasers tested, conventional edge emitting Fabry Perot laser diodes, VCSELs, and distributed feedback (DFB) laser diodes exhibited periodic oscillation of the optical power due to an instability in the coupling between the circulating optical field and the semiconductor gain medium. The instability could be locked to a microwave reference by simultaneously injecting a weak modulation current at the appropriate frequency, i.e., double locking to both microwave and optical references. Phase locked operation with sub-Hz linewidth and - 125 dBc/Hz residual phase noise was measured, values that compare favorably with other published reports A compact configuration using relatively inexpensive optical components was demonstrated. All laser types could be accurately modeled using a lumped element, coupled equation model for the circulating optical field and free carrier density. The model showed good agreement with a mapping of the types of nonlinear dynamics observed experimentally.