We report on efficient lasing of Pr-doped fluoride materials with cw output powers up to 600 mW in the visible spectral range. Praseodymium doped LiYF(4) and LiLuF(4) crystals were pumped either by an intracavity frequency doubled optically pumped semiconductor laser with output powers up to 1.6 W and nearly diffraction limited beam quality or by a multimode GaN-laser diode with an output power of about 370 mW. Furthermore, intracavity frequency doubling of the red Pr-laser radiation to 320 nm reaching output powers of more than 360 mW with a conversion efficiency of 61% and an optical-to-optical efficiency of 22% are presented.

We report, for the first time to our knowledge, diode-pumped cw laser oscillation of Pr3+:LiYF4 in the red spectral range. The pump power is provided by a GaN laser diode emitting a maximum output power of 25 mW at a wavelength of approximately 442 nm. The Pr3+ laser emits 1.8 mW of output power at a 639.7-nm wavelength. Threshold pump power and slope efficiency in a nonoptimized setup are determined to be 5.5 mW and 24%, respectively.

A high-power optically pumped semiconductor laser operating around 970 nm has been used as a pumping source for an upconversion laser based on an Er3+ doped LiLuF4 crystal. Nearly 0.5 W of continuous wave (cw) output power and 0.8 W peak power at a 50% pump duty cycle could be achieved at a wavelength of 552 nm. This represents the highest output power from a room temperature upconversion laser ever reported. Laser threshold and slope efficiency were measured to be below 100 mW of absorbed pump power and 30%, respectively. This experiment could be an important step along the route to realizing a compact and efficient upconversion laser emitting in the Watt level power regime.

We describe a new approach for the generation of coherent ultraviolet radiation. Continuous-wave ultraviolet light at 320 nm has been obtained by intracavity frequency doubling of red-emitting Praseodymium lasers. Lasing at the 640-nm fundamental wavelength in Pr:LiYF(4) and Pr:BaY(2)F(8) was realized by employing an optically pumped semiconductor laser at 480 nm as pump source.Using LiB(3)O(5) as nonlinear medium, ~19 mW of ultraviolet radiation with ~9% optical efficiency with respect to absorbed power was reached for both laser crystals; the visible-to-ultraviolet conversion efficiency was 26% and 35% for Pr:LiYF(4) and Pr:BaY(2)F(8), respectively.

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In this paper, we report on 500 mW of cw ultraviolet radiation at 360 nm, which has been obtained by intracavity frequency doubling of a Pr:YLF laser, end pumped by 1.8 W Coherent High Power OPS Laser at 479 nm. We have demonstrated the scalability of Pr:YLF laser to pump power of 5.3Watts, resulting in real continuous wave 2.5 Watts of output power at 720 nm and cw 1.3 Watts at 360 nm.

We present an air-cooled optically pumped semiconductor laser that provides a cw output power of 1W at 488 nm. This performance was achieved via intracavity frequency doubling at a laser diode pump power of 2.5 Watts. The increased efficiency was realized by optimizing the OPS chip design and improving the heat extraction from the OPS chip. Efficient cooling of the OPS chip and a compact and mechanically stable folded resonator provide maintenance-free long life laser operation with an M 2 of less than 1.1 and a noise of less than 0.25% rms. The size of the laser head is the same as for the 20 mW commercially available version, namely 125x70x34 mm.

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