Efficient high-power laser operation of Yb:KLu(WO_4)_2 crystals cut along the principal optical axes (original) (raw)
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Dual-wavelength diode-pumped laser operation of N p-cut and N g-cut Tm:KLu(WO4)2 crystals
Applied Physics B, 2013
Simultaneous continuous-wave laser oscillation at two wavelengths has been observed and studied in a diode-pumped monoclinic N p-cut Tm:KLu(WO 4) 2 for different transmission of the output coupler. The maximum output power reached 1.15 W with a slope efficiency of 20.4 % with respect to the absorbed power for polarization parallel to the N m optical axis. In an analogous N g-cut crystal, the dual-wavelength laser operation is accompanied by polarization switching with increasing pump power and the switching point depends on the output coupling. The thresholds are slightly higher, and the slope efficiency reached a maximum of 25.5 % for polarization parallel to N m at low pump levels, but at high pump levels, the oscillating polarization is parallel to N p , reaching maximum output power of 3.09 W. Simple modelling with rate equations taking into account reabsorption losses explains qualitatively the complex behavior observed in the continuous-wave laser experiments with this anisotropic biaxial laser crystal.
Prospects of monoclinic Yb:KLu(WO_4)_2 crystal for multi-watt microchip lasers
Optical Materials Express, 2015
The concept of Yb-doped double tungstate microchip lasers is verified and scaled to the multi-watt power level. The active element is a 2.6 mm-thick Yb:KLuW crystal cut along the N g optical indicatrix axis. Maximum continuous-wave output power of 4.4 W is extracted at 1049 nm with a slope efficiency of 65% and an optical-to-optical efficiency of 44% with respect to the absorbed pump power. The laser emission is linearly polarized and the intensity profile is characterized by a near-circular TEM 00 mode with M 2 x,y < 1.1. Due to low intracavity losses of the microchip laser, laser operation at wavelengths as long as 1063 nm is achieved. The mechanism of the thermal mode stabilization in the microchip cavity is confirmed. At very low resonator losses polarization-switching between E || N m and N p oscillating states is observed and explained on the basis of spectroscopic and thermal lens characteristics.
CW laser operation around 2-μm in (Tm,Yb):KLu(WO 4) 2
2010
Laser generation in continuous wave (CW) regime at 1.94-μm from (Tm,Yb) codoped system has been investigated in two different hosts: KLu(WO 4) 2 and KY(WO 4) 2. The high quality crystals were grown by the Top-Seeded Solution Growth Slow Cooling (TSSG-SC) method with doping levels of 2.5 at. %Tm and 5 at. %Yb. The active media were pumped with a diode laser at 980 nm. We demonstrated the superior performance of KLu(WO 4) 2 compared to that of KY(WO 4) 2 and improved the results already obtained in the literature. The maximum laser output power reached was 157 mW for (Tm,Yb):KLu(WO 4) 2 and 123 mW for (Tm,Yb):KY(WO 4) 2 .
Continuous-wave diode-pumped operation of an Yb:NaLa(WO4)2 laser at room temperature
Optics and Laser Technology, 2007
Room-temperature continuous-wave (cw) laser operation is demonstrated with the newly developed Yb:NaLa(WO4)2 disordered crystal by end-pumping with a fiber-coupled diode laser. A maximum output power of 330 mW is obtained with an optical efficiency of 4.9% and a slope efficiency of 6.3% with respect to the incident pump power. The efficiencies in terms of the absorbed pump power are roughly three times higher. Sellmeier dispersion curves for the ordinary and extraordinary refractive indices of the NaLa(WO4)2 host are reported along with crystallographic and spectroscopic properties related to the Yb3+-doping.
Diode-Pumped Ho-Doped KLu(WO 4 ) 2 Laser at 2.08 µm
Applied Physics Express, 2011
We report on the efficient continuous-wave diode-pumped laser operation of Ho in the monoclinic KLu(WO 4) 2 crystal at 2080 nm, resonantly pumped at a wavelength of 1941 nm by a fiber-coupled GaSb diode stack. A maximum output power of 408 mW and a slope efficiency of 54.5% with respect to the absorbed pump power were achieved. A comparison of the laser performance within the Ho-doped KRE(WO 4) 2 (Ho:KRE(WO 4) 2) family of monoclinic crystals showed a slightly superior performance of Ho:KY(WO 4) 2 , achieving a maximum output power of 438 mW and a slope efficiency of 58.8% under identical conditions.
Continuous-wave lasing of a stoichiometric Yb laser material: KYb(WO_4)_2
Optics Letters, 2003
For the first time to the authors' knowledge, continuous-wave laser emission of the stoichiometric crystal KYb͑WO 4 ͒ 2 was achieved at 1068 nm. The 125-mm-thin sample was directly water cooled and pumped at 1025 nm by a Ti : sapphire laser. The maximum output power at room temperature was 20 mW.
IEEE Journal of Quantum Electronics, 2005
Epitaxial monoclinic double tungstate composites based on the strongly anisotropic KLu(WO 4) 2 (KLuW) were grown with high crystalline quality and laser operation of ytterbium was demonstrated for the first time. Highly efficient CW laser emission of an Yb:KLuW-KLuW crystal was achieved near 1030 nm. The 100-m-thick Yb:KLuW layer was pumped at wavelengths near 980 nm by a tapered diode laser as well as by a Ti:sapphire laser. More than 500 mW of CW output power and slope efficiencies up to 66% were obtained at room temperature without cooling.
Indium-modified Yb:KLu(WO 4 ) 2 crystal: Growth, spectroscopy and laser operation
Journal of Luminescence, 2017
We report on the growth, spectroscopic and laser characterization of a novel monoclinic laser crystal, Yb,In:KLu(WO 4) 2 (Yb,In:KLuW). The absorption, stimulated-emission and gain cross-section spectra of 3.5 at.% Yb, 5.5 at.% In-doped KLuW are determined at room temperature with polarized light and compared with those for Yb,In:KYW, as well as singly Yb-doped KLuW and KYW crystals. It is found that the introduction of In results in a decrease of the transition cross-sections and in a spectral broadening of the absorption and emission bands. Such a broadening is more pronounced for light polarization E || N p. For Yb,In:KLuW, the maximum σ abs is 9.9 × 10-20 cm 2 at 980.9 nm for E || N m and the corresponding bandwidth of the absorption peak is 3.7 nm. The radiative lifetime for Yb 3+ ions is 237±5 µs. The stimulated-emission cross-sections are σ SE (m) = 2.4×10-20 cm 2 at 1022.4 nm and σ SE (p) = 1.3×10-20 cm 2 at 1039.1 nm corresponding to an emission bandwidth of >30 nm and >35 nm, respectively. The diode-pumped N g-cut Yb,In:KLuW microchip laser generated 4.11 W at 1042-1048 nm with a slope efficiency of 78%. The Yb,In:KLuW crystal is very promising for the generation of sub-100 fs pulses in mode-locked lasers due to its broadband emission characteristics.