A design for an ultrafast all-optical full subtractor based on two-dimensional photonic crystals

Abstract

A novel passive all-optical full subtractor device is realized using a two-dimensional (2-D) photonic crystal. The proposed structure is realized using the concept of beam interference in a sequence of T- and Y-shaped line-defective waveguide structures made of a linear material such as silicon with air as the background medium. The major advantage of this design approach is the avoidance of nonlinear materials and semiconductor optical amplifiers. In addition to the actual input ports, some reference input ports are also utilized to achieve the desired full subtractor functionality. The different input combinations to the full subtractor are given and optimized via several simulations. The full subtractor functionality is validated using the Opti-FDTD tool. The simulation results for the full subtractor are supported by the E-field distribution and power analysis at the output ports for different input logic values at a wavelength around 1550 nm. The proposed structure shows a fast response time of 0.16 ps, a bit rate of 6.25 Tbps, and a contrast ratio of 3.97 dB, and occupies an area of 465 µm2. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.