Infrared All-Optical Image Processing in Semiconductors Using the Nonlinear Index Due to Dynamic State-Filling

摘要

This project included basic studies of infrared nonlinear optical response and optical switching in semiconductor materials. Investigations ranged from the mid-infrared (InAs) through the 1.06 micrometers region (InP/based quaternaries) to the near-IR (GaAs/GaAlAs Multiple Quantum Wells). Mechanisms of dynamic state filling were explored; the stdy was extended to exciton resonance nonlinearities and finally the concept of enhanced carrier transport nonlinearities was introduced. This new non-local nonlinearity is due to the motion of optically induced charges within semiconductor depletion regions causing space change fields which decrease built-in fields. The optically induced change in internal fields causes nonlinear transmission due to electro-absorption, electro-refraction, and the quantum confined Stark effect. The result was the experimental demonstration of larger nonlinearities than have ever been previously measured, with a change of refractive index of 0.01 at an intensity level of 700 microwatts/sq cm. Keywords: Semiconductors, Nonlinear, Optical, Infrared lasers, Optical switches, and Bistability. (RRH)