  While single-pixel superconducting nanowire single photon detectors (SNSPDs)
have demonstrated remarkable efficiency and timing performance from the UV to
near-IR, scaling these devices to large imaging arrays remains challenging.
Here, we propose a new SNSPD multiplexing system using thermal coupling and
detection correlations between two photosensitive layers of an array. Using
this architecture with the channels of one layer oriented in rows and the
second layer in columns, we demonstrate imaging capability in 16-pixel arrays
with accurate spot tracking at the few photon level. We also explore the
performance tradeoffs of orienting the top layer nanowires parallel and
perpendicular to the bottom layer. The thermally-coupled row-column scheme is
readily able to scale to the kilopixel size with existing readout systems, and
when combined with other multiplexing architectures, has the potential to
enable megapixel scale SNSPD imaging arrays.
