Random Lasers with Coherent Feedback

Abstract

We have demonstrated lasing with resonant feedback in active random media. Recurrent light scattering provides coherent feedback for lasing. A detailed experimental study of laser emission spectra, spatial distribution of laser intensity, dynamics, and photon statistics of random lasers with coherent feedback is presented. The fundamental difference and transition between a random laser with resonant feedback and a random laser with nonresonant feedback are illustrated. We have achieved spatial confinement of laser light in micrometer-sized random media. The optical confinement is attributed to disorder-induced scattering and interference. Using the finite-difference time-domain method, we simulate lasing with coherent feedback in active random media.