All-optical half adder based on photonic crystals for BPSK signals

We propose a very compact structure for all-optical half adder based on photonic crystal in binary-phase-shift-keyed signals. The square lattice of dielectric rods in SiO₂ background has been considered for photonic crystal structure. The photonic band gap and light propagation of proposed logic structure have been accomplished by plane wave expansion and finite difference time domain methods. The proposed structure can achieve logical function when the refractive index and radius of all rods are fabricated with relaxed error tolerance within − 0.005 to 0.005 and − 3 to 3 nm, respectively.