High-Sensitivity InGaAs Photoreceiver Arrays in GaAs Waveguide*

Abstract

Integration of optoelectronic devices in a common waveguide substrate will result in superior device modules for applications in optical communication systems operating in the 1.3 - 1.5 μιη wavelength region because of the significant improvements in speed, noise performance, and reliability via reduction of parasitic reactances associated with hybrid interface of individual devices. Arrays of photoreceivers are also needed for systems such as optical cross-point switches for telecommunications[1] and analog switching applications such as CATV or for optical interconnects between very large scale integrated circuits.[2] A number of InP-based single-element waveguide photodetectors[3] have been reported in recent years. Reports of their GaAs counterparts have been scarce.[4,5] Furthermore, arrays of waveguide photoreceivers are yet to be realized in GaAs. In this paper we report the realization of a 45-element photoreceiver array in a GaAs waveguide for use at 1.3 pm optical wavelength. The photoreceiver array that utilizes InGaAs photoconductors and passive load resistors has demonstrated important advantages such as large gain-bandwidth product, high degree of compactness, and simple processing requirements. The total active area of the photoreceiver arrays was as small as 0.45×0.25 mm2 A unique feature of these photodetector and photoreceiver is their very high gain (or sensitivity) at frequency up to 1 MHz which also makes the photoreceiver array an ideal candidate for integration with guided-wave acoustooptic signal processors[6] in which the integration of more than a few tens of photodetectors with switching bandwidths in the order of 3 MHz on a single integrated circuits has thus far presented difficult problems due to thermal and chip area considerations.[7]