Slow Light Effect and Tunable Channel in Graphene Grating Plasmonic Waveguide

Yingqiu Zhang,Qiaohua Wu,Wenfeng Li,Chunlei Li,Xing Liu

doi:10.3390/photonics9020054

Abstract

A graphene plasmon waveguide composed of silicon grating substrate and a silica separator is proposed to generate the slow-light effect. A bias voltage is applied to tune the optical conductivity of graphene. The tunability of the slow-light working channel can be achieved due to the adjustable bias voltage. With an increase in the bias voltage, the working channel exhibited obvious linear blue-shift. The linear correlation coefficient between the working channel and the bias voltage was up to 0.9974. The average value of the normalized delay bandwidth product (NDBP) with different bias voltages was 3.61. In addition, we also studied the tunable group velocity at a specific working channel. Due to the tunability of this miniaturized waveguide structure, it can be used in a variety of applications including optical storage devices, optical buffers and optical switches.

Highlights

For the silica spacer with a thickness of more than 100 nm, the effect of the silicon permittivity of silica, ε0 is the dielectric permittivity of the vacuum, Vb is the bias voltage substrate on the dispersion of Surface plasmon polaritons (SPPs) modes can be ignored [31]
We focus on the slow-light effectmethod in the proposed waveguide
The two-dimenperfectly matched layer time-domain (PML) as the boundary condition utilized in following calculasional finite-difference methodis(Lumerical tions

Summary

Introduction

Ran Hao et al studied the slow-light performances and the large delay-bandwidth product in a graphene-grating waveguide [25]. Lu Hua et al realized slow light at the edge of the stopband and introduced graded grating to broaden the Photonics 2022, 9, 54 the large delay-bandwidth product in a graphene-grating waveguide [25]. Bragg equation is used to set athe gratIn this paper, a waveguide consisting of athe single layer of graphene and silicon ing waveguide parameters a specific frequency (35 the THz), and equation the slow light working grating containing a defect at cavity is proposed. The influence of the bias voltage guide comprehensively evaluated by the normalized bandwidth product on the are tunable slow light working channel is discussed.

Structure and Theory schematic diagram of the proposed graphene waveguide is

Discussion

50 V50toV70toV70 with a stepa of

Conclusions grating waveguide containing a defect was proposed