9509257 Lyon This proposal suggests new operating principles and approaches to constructing switches for optical signals. The devices proposed here utilize an asymmetric semiconductor quantum structure (such as a stepped quantum well) embedded in a parallel plate metallic waveguide. Preliminary work indicates that these structures can be used to construct ultrafast electrooptic and all-optical devices. In particular, calculations have been performed which suggest that these structures will support coupled-field (coupled electrical and optical pulses) solitons. The objectives of the proposed work are to study the physics of these structures, use this information to refine the models and calculations, and to fabricate and test devices based on these principles. The work will involve investigations of various types of asymmetric quantum structures, ultrafast electrical pulse propagation on parallel-plate metallic waveguides, and the interactions of these electrical pulses with optical pulses traveling through the semiconductor embedded within the waveguide. Molecular beam epitaxy (MBE) will be used to grow the semiconductor materials, which will then be analyzed with various optical and electrical probes. The electrical pulses will be generated and measured with ultrafast optical pulses. Building upon this new knowledge, optical switches will be designed, fabricated, and tested. ***