Band-Gap Solitons in Nonlinear Photonic Crystal Waveguides and Their Application for Functional All-Optical Logic Gating

Vakhtang Jandieri,Tornike Onoprishvili,Ramaz Khomeriki,Douglas H Werner,Levan Chotorlishvili,Daniel Erni,Jamal Berakdar

doi:10.3390/photonics8070250

Abstract

This review paper summarizes our previous findings regarding propagation characteristics of band-gap temporal solitons in photonic crystal waveguides with Kerr-type nonlinearity and a realization of functional and easily scalable all-optical NOT, AND and NAND logic gates. The proposed structure consists of a planar air-hole type photonic crystal in crystalline silicon as the nonlinear background material. A main advantage of proposing the gap-soliton as a signal carrier is that, by operating in the true time-domain, the temporal soliton maintains a stable pulse envelope during each logical operation. Hence, multiple concatenated all-optical logic gates can be easily realized paving the way to multiple-input ultrafast full-optical digital signal processing. In the suggested setup, due to the gap-soliton features, there is no need to amplify the output signal after each operation which can be directly used as a new input signal for another logical operation. The efficiency of the proposed logic gates as well as their scalability is validated using our original rigorous theoretical formalism confirmed by full-wave computational electromagnetics.

Highlights

Several analytical and numerical methods have been proposed [1,2,3] to investigate the soliton propagation in various kinds of media [4]
We provide an overview of our recent studies [21,22,23,24,25] about a realization of functional, compact and reliable all-optical logic gates, which may become key in modern computing and ultrafast optical signal processing [26,27]
We have suggested a functional all-optical scheme for compact NOT and AND logic gates in a realistic model of Kerr-type nonlinear coupled PhC [8–14] waveguides (PCWs) (C-PCWs) by using the dynamical properties of optical band-gap solitons

Summary

Introduction

Several analytical and numerical methods have been proposed [1,2,3] to investigate the soliton propagation in various kinds of media [4]. A working concept is based on the virtually “perfect digitalization” of the time-domain signals inherent to the process of band-gap soliton transmission [21,22,23,37,38,39,40,41] in periodic nonlinear media [3,42]. An analytical formalism for the propagation of temporal solitons in PhC waveguides based on a multi-harmonic treatment of the nonlinear setup is presented. A full-wave computational electromagnetics analysis, namely the finite-difference time-domain (FDTD) method [47], is utilized to demonstrate the successful operation of functional all-optical logic gates.

Formulation of the Problem

Numerical Simulations on Functional All-optical Logic Gates and Discussions

All-Optical NOT Logic Gate

All-Optical AND Logic Gate

All-Optical NAND Logic Gate

Conclusions