Suppression and restoration of disorder-induced light localization mediated by PT-symmetry breaking

TL;DR

This paper investigates how PT-symmetry breaking in optical waveguide arrays influences light localization, revealing suppression near the breaking point and gradual restoration beyond it, with implications for controlling light propagation.

Contribution

It demonstrates the dramatic effect of PT-symmetry breaking on light localization and provides insights into the transition between localized and delocalized regimes in disordered optical systems.

Findings

Localization is suppressed near the PT-symmetry breaking point due to increased diffraction.

Beyond the symmetry-breaking point, localization gradually reappears, with localized mode power increasing over propagation.

Localization strength increases monotonically with disorder, regardless of PT-symmetry state.

Abstract

We uncover that the breaking point of the PT-symmetry in optical waveguide arrays has a dramatic impact on light localization induced by the off-diagonal disorder. Specifically, when the gain/loss control parameter approaches a critical value at which PT-symmetry breaking occurs, a fast growth of the coupling between neighboring waveguides causes diffraction to dominate to an extent that light localization is strongly suppressed and statistically averaged width of the output pattern substantially increases. Beyond the symmetry-breaking point localization is gradually restored, although in this regime the power of localized modes grows upon propagation. The strength of localization monotonically increases with disorder at both, broken and unbroken PT-symmetry.