Double symmetry breaking of solitons in one-dimensional virtual photonic crystals

TL;DR

This paper investigates the phenomenon of double symmetry breaking in spatial solitons within one-dimensional virtual photonic crystals, revealing how solitons shift and restore symmetry as power increases, with potential applications in optical switching.

Contribution

It introduces the concept of double symmetry breaking in solitons within nonlinear photonic crystals with competing linear and nonlinear potentials, analyzed through numerical and analytical methods.

Findings

First SSB shifts soliton into a nonlinear stripe at low power.

Second SSB pushes the soliton off the nonlinear channel at higher power.

Results suggest potential for power-controlled light beam switching.

Abstract

We demonstrate that spatial solitons undergo two consecutive spontaneous symmetry breakings (SSBs), with the increase of the total power, in nonlinear photonic crystals (PhCs) built as arrays of alternating linear and nonlinear stripes, in the case when maxima of the effective refractive index coincide with minima of the self-focusing coefficient, and vice versa, i.e.,the corresponding linear and nonlinear periodic potentials are in competition. This setting may be induced, as a virtual PhC, by means of the EIT (electromagnetically-induced-transparency) technique, in a uniform optical medium. It may also be realized as a Bose-Einstein condensate (BEC) subject to the action of combined periodic optical potential and periodically modulated Feshbach resonance. The first SSB happens at the center of a linear stripe, pushing a broad low-power soliton into an adjacent nonlinear stripe and gradually suppressing side peaks in the soliton's shape. Then, the soliton restores its symmetry, being pinned to the midpoint of the nonlinear stripe. The second SSB occurs at higher powers, pushing the narrow soliton off the center of the nonlinear channel,while the soliton keeps its internal symmetry. The results are obtained by means of numerical and analytical methods. They may be employed to control switching of light beams by means of the varying power.