In this work, the authors investigate the new structure of all optical half subtractor in a two dimensional photonic crystal based on wave interference and phase shift keying technique. The suggested structure is designed using 10 optical waveguides and one defect in the basic structure. The numeral methods such as plane wave expansion and finite difference time domain are used to analyze the proposed structure. According to obtained results, the rise and fall times, the working bit rate, the minimum and maximum values of the normalized power at ON and OFF states for output ports are 0.1 ps, 0.05 ps, 5 Tbit/s, 77 and 17%, respectively. According to results, high switching speed, compactness, low power consumption and ultra-fast operation are the main advantages of designed optical half subtractor compared with the previous structures.

In optical processing systems, multiplexer is used to design optical devices such as arithmetic logic unit (ALU) and shift register (SR). Through this paper, we investigate the application of nonlinear photonic crystal ring resonator (PhCRR) based on nonlinear Kerr effect for realizing an all optical 2 × 1 multiplexer. The structure consists of two PhCRRs and five optical waveguides using hexagonal lattice silicon (Si) rods with a background of air. Performance of all optical 2 × 1 multiplexer is replicated with the help of finite difference time domain (FDTD) procedure at a wavelength of 1571 nm, and simulations presented an ultra-compact optical structure with ultra-fast switching speed.