A laser communication system and method are disclosed. The laser communication system includes a laser receiver system to receive a frequency-shift keyed (FSK) optical signal encoded with a plurality of data signals. The laser receiver system including an FSK differential detection system that includes a plurality of differential detection filters that can each receive the FSK optical signal and generate an output. The FSK differential detection system can demodulate the FSK optical signal into a multi-bit digital code corresponding to a frequency of the FSK optical signal based on the output of each of the plurality of differential detection filters.