Efficient single-frequency operation of a Ho:YAG ring laser at room temperature with a traveling-wave TeO<sub>2</sub> acousto-optic modulator to enforce unidirectional operation is reported. By use of a 2-at. % Ho<sup>3+</sup> -doped 10-mm-long Ho:YAG rod, end pumped by a cladding-pumped tunable Tm-doped silica fiber operating at 1.9 μm, the Ho:YAG ring laser yielded 3.7 W of single-frequency output at 2.1 μm in a diffraction-limited TEM<sub>00</sub> beam with <i>M</i><sup>2</sup> < 1.1 for an incident pump power of 8.8 W. The rf power required for unidirectional operation was 0.3 W and corresponded to an increase in cavity loss for the lasing direction (due to diffraction) of only 0.5%. The prospects for further improvement in efficiency are discussed.
© 2004 Optical Society of America
(140.3070) Lasers and laser optics : Infrared and far-infrared lasers
(140.3480) Lasers and laser optics : Lasers, diode-pumped
(140.3560) Lasers and laser optics : Lasers, ring
(140.5680) Lasers and laser optics : Rare earth and transition metal solid-state lasers
D. Y. Shen, W. A. Clarkson, L. J. Cooper, and R. B. Williams, "Efficient single-axial-mode operation of a Ho:YAG ring laser pumped by a Tm-doped silica fiber laser," Opt. Lett. 29, 2396-2398 (2004)