A novel design of all-optical 4 to 2 encoder with multiple defects in silica-based photonic crystal fiber

Abstract

An encoder logic gate is a combinational circuit that performs the coding operation on the input binary data, and 2n input lines are encoded with n bits. In this paper, we present a new design of a high-speed all-optical 4 to 2 encoder using a solid-core photonic crystal fiber (PCF) composed of pure silica. The proposed structure consisting of an optical buffer and two optical OR gates has four input ports and two output ports in a square lattice of PCF. The plane-wave expansion method is used to compute the band structure of the encoder, and the beam propagation method is applied to calculate the transmission and the electric field distribution of optical light inside the device. We demonstrate that the proposed 4 to 2 encoder can operate in the C-band, ranging from 1530 nm to 1565 nm, which is an appropriate device for telecommunication applications. The numerical results demonstrate that the normalized transmission values less than 0.02 % and greater than 95 % are supposed to be logic 0 and logic 1, respectively. The maximum delay of the encoder is 0.3 ps, and its total footprint is 50 μm × 30 μm×3 mm; thus, due to the relatively simple and low-cost fabrication of PCFs and their applications in photonics-based systems, the proposed device can be used in optical communications and networking.