Crosstalk analysis of integrated Geiger-mode avalanche photodiode focal plane arrays

Abstract

Arrays of photon-counting Geiger-mode avalanche photodiodes (APDs) sensitive to 1.06 and 1.55 µm wavelengths and as large as 256 x 64 elements on 50 µm pitch have been fabricated for defense applications. As array size, and element density increase, optical crosstalk becomes an increasingly limiting source of spurious counts. We characterize the crosstalk by measurement of emitted light, and by extracting the spatial and temporal focal plane array (FPA) response to the light from FPA dark count statistics. We discuss the physical and geometrical causes of FPA crosstalk, suggest metrics useful to system designers, then present measured crosstalk metrics for large FPAs as a function of their operating parameters. We then present FPA designs that suppress crosstalk effects and show more than 40 times reduction in crosstalk.