Materials For Fast Switching And Logic Devices

Abstract

Nonlinear optical properties of some materials, which are of current interest, are reviewed. Emphasis is put on GaAs-A1GaAs multiple-quantum-wells, bulk GaAs and CdSxSi_x-doped glasses. The use of these materials for high-speed optical logic devices is described. Optical NOR-gate operation of a GaAs-AlGaAs etalon with picosecond switch-on and off times is high-lighted. Optical materials are attractive both for device applications as well as for the fundamental understanding of their optical properties. Optical characterization of nonlinear materials is a subject of extensive research efforts by several groups. Interaction of light with matter, especially at high excitation levels, and the subsequent many-body effects are of fundamental importance. The physics of high density exciton phenomena, dynamics of electron-electron and electron-phonon interactions in semiconductors are of particular interest. Generation of femtosecond laser pulses and application of short-pulse techniques allow direct measurements of these dynamical effects with incredible time-resolution. Optical nonlinear materials play an important role in optical devices.1,2,3 Optical signal processing and ultimately optical computing depend critically on nonlinear materials. Nonlinear optical devices need materials with rapid response times, large nonlinearity and room-temperature capability. Optical bistable devices and logic gates are essential for parallel processing, while guided wave devices are needed for serial applications.