Waveguiding-assisted random lasing in epitaxial ZnO thin film

TL;DR

This paper demonstrates waveguiding-assisted random lasing in epitaxial ZnO thin films grown on sapphire, showing room temperature stimulated emission and lasing cavities formed by waveguiding effects rather than disordered scattering.

Contribution

It introduces a novel mechanism of random lasing in epitaxial ZnO films driven by waveguiding, differing from traditional disordered scattering systems.

Findings

Room temperature stimulated emission with a threshold of 900 kW/cm2.

Evidence of random lasing due to waveguiding in epitaxial ZnO.

Lasing cavities formed by self-guided light in the film.

Abstract

Zinc Oxide thin films were grown on c-sapphire substrates using pulsed laser deposition. Pump power dependence of surface emission spectra, acquired using a quadrupled 266 nm laser, revealed room temperature stimulated emission (threshold of 900 kW/cm2). Time dependent spectral analysis plus gain measurements of single-shot, side-emission, spectra pumped with a nitrogen laser revealed random lasing indicative of the presence of self-forming laser cavities. It is suggested that random lasing in an epitaxial system rather than a 3-dimensional configuration of disordered scattering elements, was due to waveguiding in the film. Waveguiding causes light to be amplified within randomly-formed closed-loops acting as lasing cavities.