Nonlinear properties of novel materials

Millimeter wave nonlinearities in semiconductor superlattices are analyzed. Self-induced transparency, giant third order susceptibilities and third harmonic generation are predicted at 250 GHz. Enhanced nonlinear optical properties of quantum dots are quantified, in agreement with experiments. Application to lasers indicates threshold current density of the order of amperes per centimeter squared, temperature independent threshold condition, and visible light emission for 50 A dots. The origin of sublinear intensity dependence of the erasure rate in barium titanate is attributed to the presence of shallow impurities. The exponent has resonances as a function of the grating wave vector, and is linear function of temperature. Self-oscillatory behavior of phase conjugate wave in self-pumped photorefractive is shown to arise from the photovoltaic effect. The first resonantly enhanced self-pumped phase conjugate mirror is demonstrated at 0.852 nm. Self-starting temporal oscillation in resonant two-wave mixing is attributed to the phenomenon of light induced drift. Third order optical susceptibilities at 10.6 micro m in semiconductor superlattices are calculated to be of the order of 10.0001 esu. Application to laser hardening of FLIR systems, using the techniques of light induced prism, shows dynamic range 10,000, subnanosecond response time, and tens of milliwatts per centimeter squared differential intensity threshold at the aperture plane.