Realization of all optical logic gates using universal NAND gates on photonic crystal platform

In this paper, the design of all-optical logic gates using the combination of universal NAND gates has been proposed. The photonic crystal structure consists of triangular lattice arrangement of air holes in silicon. Initially, the all optical NAND gate has been designed and optimized. Further, the optimized NAND gates have been used and arranged in a combination such that the combined structure behaves as an all-optical logic gate specifically, NOT, AND, OR, XOR and XNOR. The truth table for the designed all-optical logic gates has been verified at an operating wavelength of 1.55 μm. The proposed all optical gates exhibit a response period of 2.168 ps with a bit rate of 0.461 Tb/sec. Further, the contrast ratio for the designed gates has also been obtained.