Logic gate and optical half-adder designed by photonic crystal based on BPSK signals

We design a logic gate and an optical half-adder based on photonic crystal using BPSK signals. The logic gate is composed of a silicon rod array and a microcavity containing a SiO2 dielectric column, which can realize XOR and XNOR logic. The optical half adder is formed by introducing a reference beam with a fixed initial phase to the proposed logic gate. The initial phase of incident light determines the logic state of the BPSK signals. The intensity of the output light determines the output logic state. We use the plane wave expansion and finite element methods to analyze logic gates and optical half adders. The proposed logic gate and optical half-adder cover 160 µm2 and 270 µm2, the response time is 0.6 ps and 0.9 ps, respectively, and the margin difference of the output signals is 103% and 81%, respectively. Their compact structure, short response time, and large margin difference of the output signals have potential application prospects in all-optical information processing.