Sub-thermal to super-thermal light statistics from a disordered lattice via deterministic control of excitation symmetry

TL;DR

This paper demonstrates that by controlling excitation symmetry in a disordered lattice with chiral symmetry, one can deterministically tune light statistics from sub-thermal to super-thermal regimes, regardless of disorder level.

Contribution

The study introduces a method to control light statistics in disordered lattices by breaking excitation symmetry, enabling deterministic tuning of thermalization regimes.

Findings

Sub-thermal light statistics are inaccessible with single-site excitation.

Interferometric control allows spanning from sub-thermal to super-thermal regimes.

Chiral symmetry breaking enables deterministic light statistics tuning.

Abstract

Monochromatic coherent light traversing a disordered photonic medium evolves into a random field whose statistics are dictated by the disorder level. Here we demonstrate experimentally that light statistics can be deterministically tuned in certain disordered lattices, even when the disorder level is held fixed, by controllably breaking the excitation symmetry of the lattice modes. We exploit a lattice endowed with disorder-immune chiral symmetry in which the eigenmodes come in skew-symmetric pairs. If a single lattice site is excited, a "photonic thermalization gap" emerges: the realm of sub-thermal light statistics is inaccessible regardless of the disorder level. However, by exciting two sites with a variable relative phase, as in a traditional two-path interferometer, the chiral symmetry is judiciously broken and interferometric control over the light statistics is exercised, spanning sub-thermal and super-thermal regimes. These results may help develop novel incoherent lighting sources from coherent lasers.