Enhancement of brightness in microchip laser with angular filtering mirrors

Microchip lasers are very compact and efficient coherent light sources; however, their applications are restricted due to poor beam quality and limited brightness, especially in high-emission power regimes. We used a thin-film-based angular filtering mirror to substitute one of the planar resonator mirrors to solve this limitation. The angle-selective reflection suppresses the high-order transverse modes and enables lasing on the lowest-order ones, thus improving the spatial quality of the emitted beam. Our experimental results, supported by numerical simulations, demonstrate decrease of beam quality parameter M2 and a twofold increase in the brightness of emitted radiation. •Microchip laser applications are restricted due to poor beam quality and limited brightness.•Thin-film-based angular filtering mirror can substitute one of the planar microchip resonator mirrors and solve the brightness limitation in microchip laser.•We demonstrate twofold increase in the brightness of emitted radiation by experiment and confirm by numerical simulation.