This research focuses on semiconductor heterostructures grown in a Riber 32P molecular beam epitaxy machine dedicated exclusively to nonlinear optics, probably the only one in the world. Over the last several years considerable experimental and theoretical capabilities and experience have been acquired and developed to understand the band-edge nonlinearities of semiconductors and to design, fabricate, and operate nonlinear optical devices. Having under one roof capabilities for design, growth, fabrication, linear and nonlinear spectroscopy, and many-body theory has accelerated this process, leading to synergistic interactions. In the area of nonlinear materials, research will focus on the bandstructure, optical nonlinearity, and gain of strained layer superlattices, relevant as materials for low-power nonlinear devices and low-threshold lasers. Research on waveguide structures includes nonlinear directional couplers with and without current injection, as many-n phase shifter by current injection, and a 10-um intersubband-transition laser. Research on etalon structures concentrates on all- optical switches for optical communication, low- power slow-response etalons, and the sensitivity to external feedback of vertical-cavity surface- emmitting lasers. All findings for nonlinear optics apply equally well to optoelectronics, since the steady-state room-temperature band-edge properties of a semiconductor are determined solely by the carrier density however generated. //
