We present a Yb:YAG thin-disk laser with an adjustable and stable beam profile. A double-cavity geometry with an acousto-optic modulator (AOM) makes the spatial separation of the gain area, in which the central and external parts are used for L G 00 and L G 01 mode generation, respectively. By changing the loss of the AOM, the beam profile of the primary cavity is adjustable from annularity to flat-top continuously. At input pump power of 44 W, 8.5 W annular, 11.1 W shallow crater-shaped, and 12.1 W flat-topped modes were obtained. Moreover, the thin-disk laser with a multi-pass pumping scheme not only improves thermal management, but also minimizes depolarization loss, allowing the optimization of mode stability and laser performances. This Letter implies that a high-power laser with an adjustable and stable beam profile can be implemented via this scheme.

We present a 2 μm Tm:YAG disk laser multi-pass pumped by a 1 μm laser. The transitions in competition of up conversion (UC) and excited state absorption (ESA) are analyzed in detail based on a numerical model that considers stimulated emission, fluorescence, non-radiative decay, UC, andESA, showing good agreement with experiments. The proportions and fractional thermal loads of all transitions are derived quantitatively. The results show that UC and ESA are critical in Tm:YAG disk lasers, resulting in a decrease in the absorbed pump power and temperature after lasing for two different disk thicknesses. In addition, although the absorbed pump power of the 0.5 mm disk is lower than in the 1 mm case, its relatively weak UC and ESA and low total fractional thermal load can improve laser performance. A 0.5 mm Tm:YAG disk laser thus delivered the maximum output power of1.05 W with beam quality of Mx2 = 2.02 and My2 = 2.03.

No abstract

No abstract