Lasing from ordered colloidal micro-resonator arrays to random distributed systems

Abstract

{While colloidal microstructures are widely utilized to engineer ordered micro-resonator arrays with precise optical responses, intentionally harnessing their inherent structural randomness opens new ways for tailoring light-matter interactions. In this study, we investigate the profound impact of programmable structural disorder on the light-scattering and emission properties of colloidal micro-assemblies. Focusing on a dye-doped polymer system incorporating hollow silica microspheres, we demonstrate how controlled stochasticity alignment modulates the dominant optical feedback mechanisms. By manipulating surface tension-driven self-assembly, we observe a continuous morphological evolution from locally ordered, two-dimensional micro-gratings arrays to highly scattering macro-aggregates. Crucially, we show that increasing this structural disorder alters the light amplification pathway, transforming the optical emission sequentially, from distinct, localized resonant modes within well-defined cavities, through non-resonant amplified spontaneous emission (ASE), and ultimately culminating in robust random lasing (RL). Our findings underscore that integrating self-assembly principles with deterministically controlled randomness provides a powerful strategy to precisely engineer the emission regimes of photonic materials.