Lasing in random media

TLDR

Random lasers are non‑conventional lasers that rely on disorder‑induced scattering for feedback, and are classified into incoherent and coherent types, with large disorder enabling spatial confinement that underpins micro random lasers. The paper surveys random lasers with incoherent feedback. The study reviews experimental measurements of coherent‑feedback random lasers—thresholds, spectra, emission patterns, dynamics, photon statistics, speckle—and introduces theoretical models. The work enhances understanding of how light localization interacts with coherent amplification in random lasers.

Abstract

Abstract A random laser is a non-conventional laser whose feedback mechanism is based on disorder-induced light scattering. Depending on whether the feedback supplied by scattering is intensity feedback or amplitude feedback, random lasers are classified into two categories: random lasers with incoherent feedback and random lasers with coherent feedback. A brief survey of random lasers with incoherent feedback is presented. It is followed by a review of our recent experimental work on random lasers with coherent feedback, including measurement of the lasing threshold, lasing spectra, emission pattern, dynamical response, photon statistics, speckle pattern and the investigation of relevant length scales. Large disorder leads to spatial confinement of the lasing modes, that is the foundation for the micro random laser. Some theoretical models of random lasers with coherent feedback are briefly introduced. The study of random lasers improves our understanding of the interplay between light localization and coherent amplification.