| This dissertation focuses on characterizing, modeling, and utilizing the nonlinear behavior of a vertical cavity semiconductor optical amplifier (VCSOA). The nonlinearities of the index of refraction in the amplifier cause polarization dependent gain and nonlinear response to optical input. These phenomenon enable new applications for VCSOAs, such as all-optical logic regeneration and polarization conversion.; In semiconductor optical amplifiers, the index of refraction and optical intensity are coupled though the carrier density, resulting in a third-order nonlinearity. In a resonant amplifier structure, this coupling causes the optical input/output relationship to be nonlinear and wavelength dependent. The effect of this nonlinearity in vertical cavity semiconductor optical amplifiers (VCSOA) is characterized. A new theoretical description based on a modified form of the rate equations is developed and compared to experimental observations. The nonlinear I/O of a VCSOA is then applied to achieve all-optical logic regeneration. Optical gain of 10 dB, with a 6 dB improvement in signal to noise ratio is achieved. The response time of the nonlinearity is shown to be <1 ns. The theoretical model is used to investigate design optimizations and performance limits for this application.; VCSOAs also may exhibit dependence of gain on polarization state, despite their circular symmetry. This dependence is characterized and various symmetry breaking mechanisms considered to explain the behavior. Electro-optic birefringence is identified as the dominant contribution to this dependence for the VCSOA structure studied. A model to predict the modification of polarization state by the VCSOA is developed and compared to measurements. The application of polarization conversion is proposed and finally, optimization steps to modify the polarization dependence of the VCSOA considered. |
