A single photon avalanche diode based apparatus comprising: at least one array of single photon avalanche diodes configured to receive light generated externally to the apparatus, wherein the at least one array is configurable to be sub-divided into a plurality of sub-arrays, each sub-array able to receive a separate free space light communication channel; and a receiver configured to receive the output from each sub-array and output data based on the received plurality of sub-array separate free space light communication channel.