STABLE POLARIZATION SELF-MODULATION IN VERTICAL-CAVITY SURFACE-EMITTING LASERS

The characteristics of polarization self-modulation in a vertical-cavi ty surface-emitting laser (VCSEL) were studied for frequencies up to a pproximate to 9 GHz both experimentally and theoretically. Polarizatio n self-modulation was obtained by rotating the linearly polarized outp ut of the VCSEL by 90 degrees and reinjecting it into the laser. Exper imentally we simultaneously recorded time traces, optical and radio-fr equency spectra. We found for increasing modulation frequencies that t he output characteristics changed from square-wave to sinusoidal and t he VCSEL system assumed new polarization eigenstates that are differen t from the free-running VCSEL eigenstates. We modeled polarization sel f-modulation as an interband process and found a good qualitative agre ement between our experimental and numerical results. (C) 1998 America n Institute of Physics. [S0003-6951(98)01019-5].