Power-scaling Nd:YAG's quasi-four-level transition

Abstract

Increasing the output power of Nd:YAG's ⁴F_3/2→⁴I_9/2 quasi-four-level transition is attractive for providing a high-radiance source with a wavelength below 1 micron for applications at the life sciences interface, ranging and sensing, or as a vital element for next-generation display technologies, when frequency converted into the blue-green part of the visible spectrum. Reabsorption losses at the lasing wavelength combined with a relatively low stimulated emission cross-section and competition with the much stronger 1.06 micron transition, demands a configuration with high pumping intensity, comparable to the pump saturation intensity at 808nm, to achieve efficient operation. However, even with the availability of increasingly bright diode-lasers, the thermal deficit of the excitation cycle and the thermo-optic properties of the YAG host medium currently limit the achievable output power at 9xx nm. Presented here is a double-clad planar-waveguide Nd:YAG laser, operating at a lasing wavelength of 946nm with an output power in the 100W regime and better than 50% optical to optical conversion efficiency. The enhanced thermal management characteristics of the waveguide structure have enabled power-scaling well beyond that possible in a bulk laser configuration. These advantages and further power-scaling possibilities will be discussed.

SPIE Photonics West San Francisco 23-38 Jan (2010)

doi: 10.1117/12.847996