Monolithic optoelectronic switch integrating a GaAs/AlGaAs heterojunction bipolar transistor and a vertical cavity surface emitting laser

Abstract

Monolithic arrays of optical switches based on the integration of GaAs vertical cavity surface-emitting lasers (VCSELs) with heterojunction phototransistors form a flexible two-dimensional switching fabric that is useful for a variety of applications in parallel optical processing. VCSEL-based optical switches with high optical gain and contrast can perform digital logic as well as amplification and memory functions, while binary switch nodes can spatially re-route the optical signal paths at high speed in a multi-stage optical switching network. These switches can also be integrated with heterojunction bipolar transistors (HBT) to form a high speed (GB/s) electrical-to-optical (O-to-E or E-to-O) interface to VLSI electronics, thus providing simple communication between the optical switching network and the electronic control and processing functions. We describe below the first monolithic demonstration of an optoelectronic switch integrating an HBT with a VCSEL, achieving low modulation current, high current gain, and efficient electrical-to-optica1 conversion. >