Packaging and qualification of single-photon counting avalanche photodiode focal plane arrays

Avalanche Photodiode (APD) photon counting arrays are finding an increasing role in defense applications in laser radar and optical communications. As these system concepts mature, the need for reliable screening, test, assembly and packaging of these novel devices has become increasingly critical. MIT Lincoln Laboratory has put significant effort into the screening, reliability testing, and packaging of these components. To provide rapid test and measurement of the APD devices under development, several custom parallel measurement and Geiger-mode (Gm) aging systems have been developed. Another challenge is the accurate attachment of the microlens arrays with the APD arrays to maximize the photon detection efficiency. We have developed an active alignment process with single μm precision in all six degrees of freespace alignment. This is suitable for the alignment of arrays with active areas as small as 5 μm. Finally, we will discuss a focal plane array (FPA) packaging qualification effort, to verify that single photon counting FPAs can survive in future airborne systems.