<title>Quantum-well electrorefraction and optical waveguide device applications</title>

We demonstrate waveguide devices for optical fiber communications that employ unique semiconductor quantum well electrorefractive phenomena. Field- and carrier-induced effects are applied to electro-optic directional coupler switches and interferometric intensity modulators that are considerably more compact than bulk semiconductor waveguide devices. These quantum well waveguide components are -' 500 microns long, suitable for monolithic integration with semiconductor laser diodes, and limited in speed only by RC parasitics.