Directional Random Lasing in Liquid Crystal Infiltrated Metasurfaces

TL;DR

This paper demonstrates a method to achieve highly directional random lasing in liquid crystal infiltrated metasurfaces, enabling wide-angle beam steering without complex external components, which advances tunable coherent light sources.

Contribution

It introduces a novel approach to control the emission direction of random lasers using liquid crystal infiltrated metasurfaces, enabling wide-angle steering at submicron scales.

Findings

Transition from isotropic to directional emission with pump energy adjustment

Enhanced spatial coherence enables high-angle diffraction coupling

Achieved wide-angle beam steering without external components

Abstract

Random lasers (RL) emit light through multiple scattering in disordered gain media, typically resulting in isotropic emission with limited directionality control. Controlling RL emission direction in compact systems remains a challenge. Here we report directional random lasing achieved by infiltrating dye-doped nematic liquid crystals into a nanostructured silica metasurface. By adjusting pump energy, we induce a transition from uniform angular photoluminescence to a strongly directional emission peak at large angles in the amplified spontaneous emission and RL regimes. This directionality arises from enhanced spatial coherence in the strong scattering regime, enabling coupling of guided random-laser modes to high-angle diffraction through the metasurface grating. Our system demonstrates wide-angle RL beam steering at submicron scale without complex external components. These results provide a straightforward method to control RL emission directionality, advancing tunable coherent light sources and metasurface-based photonic applications.