High-power efficient and compact near- and mid-IR solid-state lasers with nonlinear optical frequency conversion

The development of powerful compact solid-state mid-IR lasers is highly relevant for applications in medicine, precision material processing, environmental monitoring, control of production processes, military and technical tasks. Recent investigations performed at IAP RAS have enabled the creation of compact and highly efficient solid-state lasers (based on Nd: YAG and Nd: YVO4, Ho: YAG and Tm: YLF crystals and Tm:Lu2O3 ceramics with diode laser pumping) capable of generating high-beam-quality radiation in the wavelength range of 1—2 µm. With the use of nonli-near optical parametric oscillators (OPOs) the radiation of these lasers is converted to the mid-IR range.

Laboratory model of Tm:YLF-based diode-pumped air-cooled CW laser with output power of 30 W at a wavelength of
1908 nm

Diode side-pumped Nd:YVO4 slab lasers with the grazing-incidence bounce geometry have been created by the research group headed by O. L. Antipov. The laser radiation at 1064 nm is efficiently converted to the mid-infrared (at a wavelength of 3391 nm) in an OPO based on a periodically poled LiNbO3:MgO crystal. The narrow bandwidth in the mid-IR region (<0.1 cm—1) is achieved by injecting He-Ne laser radiation into a single-cavity OPO.

Another important result is creation of a Tm3+:Lu2O3 ceramic laser. The ceramics was produced for the first time by Konoshima Chemicals Co., Ltd. (Japan) specially for IAP RAS. Using this ceramics, efficient laser emission at ~2095 nm (the longest wavelength emission for thulium lasers) under pumping by commercially available diodes at ~810 nm was obtained. The effect of cross-relaxation of Tm3+ ions (each absorbed pump quantum gives rise to two excited ions) ensures a more than 40% efficiency of pump power conversion to laser output power at 2 microns. Laboratory models of Tm3+:Lu2O3 lasers are created which are capable of generating cw and pulse-repetitive radiation with an average output power of more than 50 W.

Active Tm3+:Lu2 element and laboratory model
of a miniature ceramic laser