OPTICAL XOR LOGIC GATE

An all-optical XOR logic gate. In one embodiment, a single photon absorption medium is used to provide enhanced optical response of a gate to an applied optical signal. The apparatus described uses at least two gate inputs and an optical modulation structure such as a Mach-Zehnder interferometer to perform logical XOR operations on an optical input signal using the gate inputs. The result of the XOR operation is provided as information in an optical output signal representative of the result of the XOR operation impressed on the optical input signal.