Emission Spectrum of Random Lasers

Abstract

In recent years advances in microstructuring techniques have made it possible to manufacture novel mirrorless cavities known as random lasers. Examples for this new type of laser include strongly disordered semiconductors [1, 2], polymer systems [3], solutions of TiO ₂ nanoparticles [4, 5], as well as synthetic opals infiltrated with laser dyes [6]. The feedback in random lasers is provided by the random scattering of light in a dielectric with a spatially fluctuating refractive index. Light amplification results from the interaction with a medium of active atoms. The interest in random lasers is motivated both by possible applications and by their novel emission properties. Due to their intrinsic randomness such lasers often emit light in a large solid angle (up to 4 π). Moreover, random lasers are cheap and can easily be designed with different shape and size. These properties may prove useful for applications in computer displays and photonic devices. In this paper we discuss our present theoretical understanding [7, 8] of random lasers.