Estudo do desempenho do interferômetro de Michelson de fibras de cristal fotônico para aplicações em circuitos lógicos nas configurações on-off e ppm

Abstract

In this work, we present a numerical investigation of the performance of a fully optical device, composed of a double directional coupler, followed by two symmetrically identical Bragg gratings, recorded in his arms out, setting up a Michelson interferometer with features a filter add / drop. We consider the propagation of ultrashort pulses (order of femtoseconds) over the entire length of the system. Higher order effects such as third-order dispersion, intrapulse Raman scattering and self-steepening were included in the generalized nonlinear Schrödinger equation governing the pulse propagation. The research is conducted through numerical simulations, using the method Runge Kutta fourth order. We work with two different applications. Firstly, we conduct the study of the device in an on-off system in three distinct regimes of pumping power: below the critical power (Po = 150 kW), critical power (Pc=177 kW) and power above the critical (Po = 196 kW). We determine several relevant quantities to characterize system performance, such as transmission, extinction rate, crosstalk and compression factor as a function of dephasing added to one of the Bragg gratings Michelson interferometer. Furthermore, we use the device as a two input logic gate, according to the four possible combinations of two pulses, on the input fibers 1 and 2, to obtain the logic functions XOR, OR and NOT. In a second step, the four possible combinations for two pulses, on the input fibers 1 and 2, modulated by the Temporal Pulse Position (PPM) in the logical levels 0 or 1, were used. The effects of a variation in the coding parameter offset (ε) (of the PPM modulation), in the initial position of the pulse associated to the reference pulse or unmodulated information, have been investigated and an OR gate, has emerged. Through the analysis of output pulses, we studied the Signal to Noise Ratio (SNR) for the construction of a figure of merit, with the aim of comparing the performance of logic gates obtained.