Photo-resonator optical detectors and optical receiver systems incorporating same, In one example, an optically resonant detector includes a housing having an optical window, a photodetector disposed within the housing, and an optical resonator disposed in optical alignment with the photodetector within the housing and positioned between the optical window and the photodetector, the optical resonator being configured to receive an input optical signal via the optical window and to provide an output optical signal to the photodetector.