Disk laser

A disk laser or active mirror (Fig.1) is a type of diode pumped solid-state laser characterized by a heat sink and laser output that are realized on opposite sides of a thin layer of active gain medium. Despite their name, disk lasers do not have to be circular; other shapes have also been tried. The thickness of the disk is considerably smaller than the laser beam diameter.

The disk laser concepts allows very high average and peak powers due to its large area leading to moderate power densities on the active material.

Active mirrors and disk lasers

Initially, disk lasers were called active mirrors, because the gain medium of a disk laser is essentially an optical mirror with reflection coefficient greater than unity. An active mirror is a thin disk-shaped double-pass optical amplifier.

The first active mirrors were developed in the Laboratory for Laser Energetics (USA). Then, the concept was developed in various research groups, in particular, the University of Stuttgart (Germany) for Yb:doped glasses.