Design of wavelength division multiplexing devices based on tunable edge states of valley photonic crystals

TL;DR

This paper proposes a novel all-dielectric silicon topological valley photonic crystal-based WDM device that offers low loss, tunable wavelength channels, and compact design, advancing integrated photonic circuits.

Contribution

It introduces a tunable topological valley photonic crystal design for WDM devices with adjustable wavelength channels in the telecommunication range.

Findings

Two channels with high contrast ratios (22.4 dB and 24.9 dB) achieved.

Effective refractive index tuning enables continuous wavelength adjustment.

Broad applicability in designing various integrated photonic devices.

Abstract

Wavelength division multiplexing (WDM) devices are key elements of Photonic integrated circuits (PICs). Conventional WDM devices based on silicon waveguides and photonic crystals have limited transmittance due to high loss introduced by the strong backward scattering from defects. In addition, it is challenging to reduce the footprint of those devices. Here we theoretically demonstrate a WDM device in the telecommunication range based on all-dielectric silicon topological valley photonic crystal (VPC) structures. We tune its effective refractive index by tuning the physical parameters of the lattice in the silicon substrate, which can continuously tune the working wavelength range of the topological edge states, which allows designing WDM devices with different channels. The WDM device has two channels (1470 nm-1523 nm and 1548 nm-1609 nm), with contrast ratios of 22.4 dB and 24.9 dB, respectively. The principle of manipulating the working bandwidth of the topological edge states can be generally applied in designing different integratable photonic devices, thus it will find broad applications.