Nonlinear switching of low-index defect modes in photonic lattices

TL;DR

This paper investigates nonlinear signal switching in photonic lattices with low-index defect channels, revealing a Bragg-type coupler that functions as an all-optical switch with power differences based on nonlinearity type.

Contribution

It introduces a novel nonlinear switching mechanism in photonic lattices with low-index defects, distinct from conventional couplers, controlled by lattice parameters and nonlinearity.

Findings

Bragg-type coupler exhibits all-optical switching behavior.

Switching power differs for focusing versus defocusing nonlinearity.

Coupling length is tunable via lattice parameters and channel spacing.

Abstract

We address nonlinear signal switching between two low-index defect channels induced in periodic optical lattices. In contrast to conventional directional couplers, where the guiding mechanism is total internal reflection or refraction, in such Bragg-type coupler, the guidance is of a photonic-bandgap origin. The coupling length in the low-index coupler is controlled by the lattice parameters and by the channel spacing. In the nonlinear regime the Bragg-type coupler behaves as an all-optical switch, exhibiting a remarkable difference of switching power for focusing versus defocusing nonlinearity.