Taming random lasers through active spatial control of the pump

TL;DR

This paper demonstrates a numerical method to control and select specific lasing modes in random lasers by shaping the pump profile, effective even in weak scattering regimes, enabling robust single-mode operation.

Contribution

It introduces an iterative optimization approach for active spatial control of the pump to select desired lasing modes in random lasers, including in weak scattering conditions.

Findings

Successful mode selection via pump shaping in strong scattering regimes.

Effective mode control achieved even in weak scattering regimes.

Potential for robust single-mode operation of random lasers.

Abstract

Active control of the pump spatial profile is proposed to exercise control over random laser emission. We demonstrate numerically the selection of any desired lasing mode from the emission spectrum. An iterative optimization method is employed, first in the regime of strong scattering where modes are spatially localized and can be easily selected using local pumping. Remarkably, this method works efficiently even in the weakly scattering regime, where strong spatial overlap of the modes precludes spatial selectivity. A complex optimized pump profile is found, which selects the desired lasing mode at the expense of others, thus demonstrating the potential of pump shaping for robust and controllable singlemode operation of a random laser.