Investigation on PhC based T-shaped waveguide as all-optical XOR, NOT, OR and AND logic gates

In this article, we propose a simple photonic crystal based T-shaped waveguide as XOR, NOT, and OR logic gates, and as an AND gate with small modification in the radius of its directional rods. The operation of the waveguide as a proposed logic gate structure depends upon the phase of the input light applied. The phase of the light applied to port A of the waveguide is zero whereas it varies for port B. For the NOT gate, port B is used to apply the reference input with 180° phase. The phase of the input light applied to port B is zero for OR and AND while it is 180° for XOR. Numerical analysis is carried out by simulating the proposed logic gate structure at a wavelength of 1550 nm for all the logic gates using Finite Difference Time Domain method. The results show that the ON to OFF contrast ratio of XOR and NOT gates is 54.91 dB while it is 6.02 dB for AND gate, with a fast response time of less than 0.15 ps. Finally, it can be concluded that, the proposed simple and common logic gate structure with fast output response allows it to be utilized as a basic component in the future Photonic Integrated Circuits.