Design and Simulation of Reconfigurable Optical Logic Gates for Integrated Optical Circuits

The proposed work presents a new structure that can be used as reconfigurable optical logic gates. This structure is constructed in a two dimensional (2D) photonic crystals (PhCs). Logic gates like AND, NOT and NOR are realized by using the proposed structure. These optical logic gates are constructed in 6 µm * 6 µm in 2D PhCs square lattice with a lattice constant a=0.648 µm. All the gates are realized by creating structural disorders in the cross-waveguide geometries of 2D PhCs. The several performance parameters are examined using this structure and observed that proposed structure has reduced size, fast response time of 0.46ps, high bit rates of 2.14Tbits/sec and better contrast ratio of 8.6dB against the existing designs. The signal amplitude larger than 0.5 arbitrary units (a.u.) and less than 0.1 (a.u.) at output are considered as logic ‘1’ and ‘0’ respectively. The plane wave expansion (PWE) is utilised to get the band gap for this logic gate 2D PhC structure and the finite difference time domain (FDTD) technique is utilised to investigate their performance in terms of light travelling in the crystal lattice structure. The gates are implemented in third optical window at the wavelength of 1.55 µm and can be used in photonic integrated circuits for signal processing in optical communication.