Diode-pumped industrial high-power cw all-solid state laser at 266 nm

The first cw high-power deep UV laser at 266 nm is accomplished by an intracavity frequency doubled and externally quadrupled diode-pumped Nd:YAG laser. The quadrupling stage is an actively stabilized unidirectional ring cavity based on the patent-pending DeltaConcept, where a minimum number of optical components--two mirrors and one prism are used. The symmetrical Brewster-angled beam path through the prism guarantees minimum losses and hence maximum power enhancement and efficiency. The cavity length control is done by moving the prism along its symmetry axis using a piezoelectric element. The beam path in the cavity remains not only completely unaffected during this movement but also unaffected in the first order by small tilts of the prism due to possible imperfection of the piezoelectric element. Furthermore, the stabilization loop has excellent dynamic behavior owing to the small mass of the prism. Minimum losses result in a power enhancement up to 150. The unique feature of the DeltaConcept shown above adopted in the 266 nm laser results in high beam pointing stability of < 2 (mu) rad/ degree(s)C and long term deep UV power stability of < 2% over 10 hours. By using Brewster-cut BBO crystals the high-power deep UV cw laser can deliver 266 nm radiation with an output power of 1.5 Watt at a green pumping power of 5 W. First slim design of the whole laser was realized to meet rough requirements posed by industrial applications. This slim design is the ideal replacement of traditional gas and ion UV lasers.