Power Limits of Compact Ho3+:YAG Laser Resonators with Homogeneously Doped and Segmented Crystals

Laser light from Ho 3+ : YAG crystals in the 2 μm range has a variety of applications like remote sensing, medical applications, or the pumping of optical parametric oscillators for the generation of mid-infrared radiation. When working with this quasi-three-level laser material, a high pump intensity is required which can be generated in an end-pumped design. However, such a design leads to a large longitudinal temperature gradient resulting from the exponential absorption of the pump light. One approach to decrease the temperature peak at the front of the crystal and therefore reduce temperature-induced stresses in the crystal is the use of diffusion-bonded crystals consisting of multiple segments with increasing doping concentrations along the crystal axis [1].