Design of ultra compact all-optical XOR, XNOR, NAND and OR gates using photonic crystal multi-mode interference waveguides

We propose ultra compact all-optical XOR, XNOR, NAND and OR gates based on photonic crystal multi-mode interference waveguides for binary-phase-shift-keyed signals. The logic gates have been simulated and analyzed by finite difference time domain method. The extinction ratio between the ON state and the OFF state for XOR, XNOR, NAND and OR gates are more than 28.6 dB, 28.6 dB, 25 dB and 26.6 dB in the whole C-band, respectively. The proposed structure can achieve logical function when the radius of all rods is fabricated with relaxed error tolerance within - 10% to 30% from designed parameters. The device possesses ultra compact size with approximately 6.9 mu m x 6.7 mu m. The proposed logic gates may potentially be used as key components in all-optical information networks for processing binary-phase-shift-keyed signals. Crown Copyright (c) 2013 Published by Elsevier Ltd. All rights reserved.