Search and Characterization of Optical Ceramics and Crystals for Diode-pumped Laser Oscillations

Glass matrix doped with rare-earth ions is a promising laser active medium for high power laser systems. Due to amorphous structure of glasses the absorption and emission spectra lines are broader in comparison with crystalline materials thus pumping radiation can be absorbed efficiently, moreover much broader gain bandwidth is suitable for generation of ultra-short pulses. Another advantage of the glass matrix is the possibility to fabricate large volume ingots and simultaneously preservation of sufficient optical quality. The lower thermal conductivity of glasses can be compensated by geometry of the active medium for instance shaped into fibres or discs. We present temperature dependence of spectroscopic and laser properties of newly developed Er, Yb - doped potassium-lanthanum phosphate glass, which is appropriate for generation of radiation at 1.53 μm. The sample of Er,Yb:KLaP glassy mixture was cut into disc shape with dimensions of 2.5 mm (thickness) and 5 mm (diameter) and its faces were polished plan-parallelly without being anti-reflection coated. The temperature dependence of the transmission and emission spectra Er,Yb:KLaP together with the fluorescence decay time were measured the temperature range from 80 to 400 K. The fluorescence lifetime of manifold 4I13/2 (upper laser level) prolonged and the intensity of up-conversion radiation decreased with decreasing temperature. The longitudinal excitation of Er,Yb:KLaP was carried out by a fibre-coupled laser diode (pulse duration 2 ms, repetition rate 10 Hz, pump wavelength 969 nm). Laser resonator was hemispherical, with flat pumping mirror (HR @ 1.5 μm) and spherical output coupler (R = 98 % @ 1.5 - 1.6 μm). The Er,Yb:KLaP glass laser properties were investigated in the temperature range 80 - 300 K. The highest slope efficiency with respect to absorbed pumped power was 6.1 % at 80 K. The maximum output of peak amplitude power was 0.71 W at 80 K, i.e. 1.2 times higher than at 300 K. Tunability of laser wavelength at 80 K in range 1528 - 1552 nm was obtained using MgF2 birefringent filter. From our measurement it can be concluded, that spectroscopic and laser properties of newly developed Er,Yb:KLaP glass are slightly temperature dependent.

ABSTRACTTrivalent rare earth ions in crystalline or fiber hosts are among the most successful of laser materials, but new dopant-host combinations and more detailed understanding of existing materials continue to be needed. This paper presents a few examples from the work of our team at the Army Research Laboratory, highlighting the interrelation between spectroscopic properties and laser behavior. It focuses on bulk solids, though rare-earth-doped fiber lasers are also extremely important. One system discussed is Nd:YAG, particularly concentration quenching in heavily doped ceramic YAG. Spectroscopic properties of Yb:Y2O3 and Yb:Sc2O3 help to elucidate their laser performance. Spectra indicate that Er:YAG is more promising than Er:Sc2O3 for room temperature laser operation, but that the reverse is true for operation at and somewhat above liquid nitrogen temperature.

Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material

In this paper the optical spectroscopic properties of Yb 3+ /Er 3+ co-doped antimony-phosphate glasses were investigated. The absorption and luminescence spectra were measured and the emission cross-section for 4 I 13/2 -> 4 I 15/2 transition of Er 3+ was calculated on the basis of McCumber theory. The resonant energy transfer (ET) between Yb 3+ -> Er 3+ ions was investigated pumping at 976nm. As a result of optimization of rare earth concentration the best efficiency of energy transfer in fabricated glasses was obtained for molar composition 1%Y 2 O 3 : 0.5%Er 2 O 3 . Full Text: PDF References M. Liao, Z. Duan, L.Hu, Y. Fang, L.Wen,"Spectroscopic properties of Er 3+ /Yb 3+ codoped fluorophosphate glasses", J. Lum 126 139 (2007) [CrossRef] L. Zang, H. Hu, C. Qi, F. Lin,"Spectroscopic properties and energy transfer in Yb 3+ /Er 3+ -doped phosphate glasses", Opt. Mat. 17 371 (2001) [CrossRef] J. F. Philipps, T. Töpfer, H. Ebendorff - Heidepriem, D. Ehrt, R.Sauerbrey,"Appl. Phys. B72 399 (2001)", Spectroscopic and lasing properties of Er 3+ :Yb 3+ -doped fuoride phosphate glasses [CrossRef] Y. Fang L. Hu, M. Liao L. Wen J. Alloys Comp. 457 19 (2008) Qian, C. Zhao, G.F. Yang, Z.M. Yang, Q.Y. Zhang, Z.H. Jiang"Spectroscopic properties of Er 3+ -doped Na 2 O?Sb 2 O 3 ?B 2 O 3 ?SiO 2 glasses", J. Non-Cryst. Solids 354 1981 (2008) [CrossRef] W.J. Miniscalco, R.S. Quimby,"General procedure for the analysis of Er3+ cross sections", Opt. Lett. 16 (1991) [CrossRef] Q. Qian, Q.Y. Zhang, H.F. Jiang Z.M. Yang, Z.H. Jiang,"The spectroscopic properties of Er 3+ -doped antimony?borate glasses", Physica B 405 2220 (2010) [CrossRef]

We fabricated highly transparent Yb3+-doped rare-earth sesquioxide ceramics for solid-state lasers and demonstrated the ceramic lasers. The spectroscopic properties were measured for the low temperature laser operation.

We fabricated highly transparent Yb3+-doped rare-earth sesquioxide ceramics for solid-state lasers and demonstrated the ceramic lasers. The spectroscopic properties were measured for the low temperature laser operation.

Spectral kinetic study of four-component BaF2–ZnF2–CdF2-YbF3 fluoride ceramics by selective laser excitation

Better understanding of the role of SiO2, P2O5 and Al2O3 on the spectroscopic properties of Yb3 + doped silica sol-gel glasses

Spectroscopic properties of Nd <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions in SrF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -CaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> solid solutions were investigated. The absorption and fluorescence spectra of different individual and clustered optical centers were observed depending on Nd <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions concentration. The laser properties of SrF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> :Nd <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> crystal with neodymium ions concentration of 0.5 at.% containing high symmetry cubic and tetragonal optical centers together with low symmetry clusters were investigated under diode pumping. Using temperature tuning of laser diode pumping wavelength two different lines centered at about 1037 nm and 1044 nm attributed to oscillation of different optical centers were obtained. The slope efficiency of 17% was obtained for short wavelength oscillations at 1037 nm without optimization. The distribution of the output energy between the two oscillating lines for several wavelengths of laser diode pumping. The comparison with LaF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> :Nd <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> crystal having single type of Nd <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> optical centers was carried out.

The spectroscopic and laser properties of Er:YLF crystal, that is appropriate for generation at 2.8 μm, in temperature range 80 - 300 K are presented. The sample of Er:YLF (6 at. % of Er3+) had face-polished plan- parallel faces without anti-reflection coatings (thickness 9 mm). During experiments the Er:YLF was attached to temperature controlled copper holder and it was placed in vacuum chamber. The transmission and emission spectra together with the fluorescence decay time were measured depending on temperature. The excitation of Er:YLF was carried out by a laser diode radiation (pulse duration 5 ms, repetition rate 10 Hz, pump wavelength 972 nm). Laser resonator was hemispherical, 100 mm in length with flat pumping mirror (HR @ 2.8 μm) and spherical output coupler (r = 100 mm, R = 95 % @ 2.65 - 2.85 μm). The tunability of laser at 80, 200 and 300 K was tested using MgF2 birefringent filter and several laser lines in wavelength range from 2709 nm to 2860 nm were observed. The fluorescence decay time of manifold 4I11/2 (upper laser level) became shorter and intensity of up-conversion radiation was increasing with decreasing temperature. In pulsed regime, the highest slope efficiency with respect to absorbed mean power 23 % and the maximum output energy 12.5 mJ were reached. The laser radiation generated by Er:YLF laser (2.81 μm) is close to absorption peak of water (3 μm) thus this wavelength can be use in medicine and spectroscopy.

Stark splitting and spectroscopic properties improvement of Yb3+-doped phosphate glass with SiO2 modification

Fluorescence and Spectroscopic Properties of Yb3+-Doped Phosphate Glasses

Crystal growth, optical spectroscopy and laser experiments on new Yb3+-doped borates and silicates

Spectroscopic properties of Yb 3+-doped silicate glasses

Influence of TeO 2, PbF 2, ZnF 2 on the spectroscopic and lasing properties of Yb 3+ doped fluorophosphate glass