Design and analysis of optical logic gates based on trifurcation structured 2D photonic crystals

Abstract

In this paper, a trifurcation structured optical logic gates is designed based on 2D photonic crystals that is composed of square lattice air holes in silicon. The results of the proposed structure confirm that it could exhibit the optical logic gate functionality of OR, AND, NOR and NAND gates. These gates were designed with three inputs port and single output port. Out of the three inputs, the centre port is considered as the reference input. The inputs are followed by a square shaped resonator design. The bit rate and footprint are calculated for the proposed optical logic gates. The contrast ratio for AND, NAND and NOR gate is 6.15 dB, 5.79 dB and 2.97 dB respectively. Additionally, phase shifts are introduced in the launch field to improve the contrast ratio and it is found that certain logic functions display improved power output. The contrast ratio for AND, OR gate (with 180° phase shift) is 6.52 dB and 10.79 dB, respectively. The footprint for the proposed gate is 424.7 μm. Plane wave expansion and finite difference time domain method are used to calculate the band structure and wave propagation of the structure.