Limitations of homogeneous and segmented single-crystal compact TEM$_{00}$-mode Ho$^{3+}$:YAG laser resonators

We present investigations on output power limitations of near-diffraction-limited compact Ho$^{3+}$:YAG laser resonators employing a homogeneous or segmented laser crystal. An approach for designing a segmented crystal is presented. Maximum output powers of 57.6W and 51.9W are reached with the homogeneous and segmented crystal, respectively, resulting in pulse energies of 1.14mJ and 1.04mJ at a repetition rate of 50kHz in Q-switched operation. Interferometric experiments are conducted to derive the radial temperature profile for both crystals. Simulations based on a split-step beam propagation method are used to model the longitudinal temperature gradient in both crystals.