High-power red, orange, and green Pr^3+:LiYF_4 lasers

Abstract

Laser experiments with Pr(3+):LiYF4 under excitation with a frequency doubled optically pumped semiconductor laser emitting 5 W at 479 nm were performed at seven different laser wavelengths of 523, 546, 604, 607, 640, 698, and 720 nm. At all these wavelengths the output power exceeded 1 W. The best performance at 523 nm with an output power of 2.9 W at a slope efficiency of 72% and an optical-to-optical efficiency of 67% with respect to the incident pump power represents the highest efficiency ever reported for a praseodymium-doped laser material.

Power scaling of blue-diode-pumped Pr:YLF lasers at 523.0, 604.1, 606.9, 639.4, 697.8 and 720.9 nm

“…For all lasers except the orange, we estimated the internal round-trip cavity losses 2γ int : in the light of the energy conservation law, the internal round-trip cavity losses for the corresponding transmission of OC could be determined in [7].…”

“…In order to achieve these visible lasers, the photons need to be pumped from ground-state level 3 H 4 to excited energy level 3 P 0 (around 480 nm), 3 P 1 þ 1 I 6 (around 469 nm), or 3 P 2 (around 444 nm). Therefore, three efficient pump sources have ever been developed to meet the pumping demands, i.e., optically pumped and frequency-doubled semiconductor lasers (OPSLs) at ∼480 nm [7], diode-pumped and frequency-doubled Nd:YAG laser at ∼469 nm [8,9], and InGaN laser diodes at ∼444 nm [10][11][12].…”

“…a maximum output power up to 2.9 W in green was achieved [7]. However, at present, the OPSLs operating at the blue spectral domain are still expensive, cumbersome and on-demand.…”

InGaN-LD-Pumped Continuous-Wave Deep Red Laser at 670 nm in Pr3+:LiYF4 Crystal

“…The emission cross section at 670 nm of Pr 3+ in YLF crystal is the smallest one in comparison with those at 640 nm or 607 nm. However, the emission cross sections at 670 nm, 523 nm and 696 nm are comparable, and the later two emissions have been demonstrated as a good candidate of visible solid-state lasers [6], [7]. We expect the 670 nm emission in a Pr:YLF crystal to be a new promising visible laser.…”

Laser Active Materials for High-Intensity Lasers

“…Most importantly (see the energy level diagram reported in Fig. 9), it can give rise to multicolor laser emissions (emitting levels 3 P 0 and 3 P 1 ), the most efficient ones occurring in the green-to-red spectral domain at laser wavelengths of about 523, 546, 607 and 640 nm [37], [38], and also in the deep-red and the near infrared at 698 [39] and 915 nm [40], with laser efficiencies ranging between about 25% and 65%.…”