2-mJ single-axial-mode gain-switched Cr:forsterite lasers

Single-longitudinal-mode operation of gain-switched Cr4+ laser, with output energy as much as 1.9 mJ, is reported from two different coupled-cavity resonators. A prism-coupled cavity and a modified Michelson interferometric grazing-incidence (MIGI) cavity was pumped by a multilongitudinal-mode Q-switched Nd:YAG laser; the modified MIGI cavity obtained 100-MHz-bandwidth laser output tunable between 1150 and 1330 nm. Conversion efficiency of 3.2% (slope efficiency of 4%) was achieved, with a pump threshold density as small as 0.2 J/cm2. Mode spacing of the laser output in multilongitudinal mode showed increased mode spacing in agreement with a coupled-cavity theory.