Abstract

Surface reflective second harmonic generation (SRSHG) from materials has been a powerful technique for studying nonlinear properties of semiconductors.^1-2 However, many semiconductors can only be prepared in thin epitaxial layers and the nonlinear optical properties of multilayers have rarely been investigated. Analytical models for SRSHG from a single slab³ and for a single layer⁴ have been developed. However, approximations such as a small difference of refractive indices between the film and the substrate lead to the neglect of multiple reflections in the film. Recently, S. Janz, et al., reported SRSHG from a multilayer AlGaAs-GaAs structure based on quasiphase-matching (QPM) theory,⁵ again without the consideration of multiple reflections. They observed enhancement of second harmonic output over bare GaAs, but with poor agreement between experiment and theory. We seek improvement first by understanding the role of multiple reflections in a single layer and then applying this to multiple reflections in multilayer films.

© 1994 Optical Society of America