An optical phase detector circuit is provided that is suitable for use in an optical phase lock loop. The optical phase detector includes a first optical flip-flop circuit configured to produce a first digital output based on ON/OFF state of a first digital optical input and a digital electrical control signal. A second optical flip-flop circuit is configured to produce a second digital output based on ON/OFF state of a second digital optical input and the digital electrical control signal. An AND gate is operably coupled to both the first and second optical flip-flops. The AND gate produces the digital electrical control signal for supply to the first and second optical flip-flop circuits according to an AND function of the first and second digital outputs produced by the first and second optical flip-flop circuits.