Two-dimensional indium gallium arsenide avalanche photodiode arrays for high sensitivity, high speed imaging

A 32 /spl times/ 32 element InGaAs focal plane array was demonstrated. These arrays may find application in 3-dimensional imaging systems. APD arrays will be advantageous in these systems since the bandwidths required of the readout integrated circuits push their noise performance into the regime where avalanche photodiodes are useful. Further work is underway on both readout integrated circuits for the arrays, as well as integrated microlenses that will improve the fill-factor of the arrays.

I Introduction

Demonstrations of three-dimensional imaging using a raster-scanned laser and a single detector have shown the utility of the three-dimensional technique in a wide variety of military applications. There is currently substantial effort being expended in the development of “flash” three dimensional imaging in which the return of a single laser pulse is timed, pixel-by-pixel, using a two-dimensional focal plane array. InGaAs Avalanche photodiodes (APDs) provide higher sensitivity than InGaAs PIN or HgCdTe PIN detectors in the eye-safe 1.55?m band which translates into greater range for a given laser pulse energy. Progress towards large area InGaAs APD arrays is reported here.