In the present work we report on the growth, spectroscopy and laser results of diode pumped Pr-doped LiYF(4), LiLuF(4) and LiGdF(4) fluoride, scheelite-type structure crystals. We measured the polarisation dependent absorption and emission properties as well as the decay time of the (3)P(0) level. Exploiting the (3)P(2) absorption around 444 nm, we obtained efficient laser emission under GaN laser diode pumping on several transitions from the green to the near infrared wavelength range.

We report on bulk optical refrigeration of Yb:YLF crystal to a temperature of ~124 K, starting from the ambient. This is achieved by pumping the E4-E5 Stark multiplet transition at ~1020 nm. A lower temperature of 119±1 K (~-154C) with available cooling power of 18 mW is attained when the temperature of the surrounding crystal is reduced to 210 K. This result is within only a few degrees of the minimum achievable temperature of our crystal and signifies the bulk solid-state laser cooling below the National Institute of Standards and Technology (NIST)-defined cryogenic temperature of 123 K.

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We measure the minimum achievable temperature (MAT) as a function of excitation wavelength in anti-Stokes fluorescence cooling of high purity Yb3+-doped LiYF4 (Yb:YLF) crystal. Such measurements were obtained by developing a sensitive noncontact thermometry that is based on a two-band differential luminescence spectroscopy using balanced photo-detectors. These measurements are in excellent agreement with the prediction of the laser cooling model and identify MAT of 110 K at 1020 nm, corresponding to E4–E5 Stark manifold transition in Yb:YLF crystal

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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 the present work we report on the growth, spectroscopy and laser results of LiLuF(4):Pr(3+) 1.25% in the melt. Room temperature polarized absorption and emission spectra have been recorded and the decay time of the (3)P0 manifold has been measured. Finally efficient room temperature laser emission have been obtained at 522.8 nm, 607.25 nm, 640.17 nm and 721.5 nm under 480 nm pumping by means of an optically pumped semiconductor laser.