Laser Properties Of Yb Research Articles

Crystal growth, thermal and laser properties of Yb:CTGS single crystal

The catangasite Ca3TaGa3Si2O14 (CTGS) single crystal is considered to be a promising self-frequency-doubling material for visible lasers. In this work, a CTGS single crystal with Yb-doping was successfully grown by the Czochralski method for the first time. The as-grown crystal showed yellowish coloration. The temperature dependent thermal properties, such as thermal expansion, specific heat, thermal diffusivity and thermal conductivity, were systematically investigated. The anisotropy of thermal expansion is rather small. Furthermore, its thermal conductivity is comparable to those well-known self-frequency-doubling laser crystals. In laser operation, a maximum continuous wave output power of 4.2 W at the wavelength of 1047 nm was obtained under the output coupler of 5%. These characteristics are very beneficial to laser applications.

Hot pressing of Yb:Y2O3 laser ceramics with LiF sintering aid

Transparent ytterbium-doped yttria ceramics, 2 at.% Yb:Y 2 O 3 , were fabricated by hot uniaxial pressing in vacuum at 1550 °C/50 MPa followed by a two-stage Hot Isostatic Pressing (HIPing) at 1200–1400 °C/100 MPa, using nanopowders obtained by self-propagating high-temperature synthesis (with lithium fluoride serving as a sintering aid). The addition of LiF during the powder synthesis markedly changed the morphology of powders, and at the stage of hot pressing, drastically reduced the carbon contamination of ceramics, as well as stimulated sintering without formation of the liquid phase. The spectroscopic properties of ceramics were studied. The stimulated-emission cross-section for Yb 3+ ions is 0.90 × 10 −20 cm 2 at 1030.4 nm and the luminescence lifetime is 797 μs. A continuous-wave 2 at.% Yb:Y 2 O 3 ceramic laser generated an output power of 735 mW at 1027–1034 nm with a slope efficiency of 64.5% and a laser threshold of 0.28 W. • Yb:Y 2 O 3 ceramic is produced by HPing and two-stage HIPing at 1200–1400 °C/100 MPa. • Lithium fluoride is used as a sintering aid improving the optical quality of ceramics. • The microstructure, spectroscopic and laser properties of Yb:Y 2 O 3 ceramic are studied. • The stimulated-emission cross-section for Yb 3+ ions is 0.90 × 10 −20 cm 2 at 1030.4 nm. • Yb:Y 2 O 3 ceramic laser generated 735 mW at 1027–1034 nm with a 64.5% slope efficiency.

Yb:GdScO3 crystal for efficient ultrashort pulse lasers.

We present, to the best of our knowledge, the first demonstration of thermal, optical, and laser properties of Yb:GdScO3 for potentially efficient ultrashort pulse lasers. The stimulated emission cross section at 1025 nm (E//c) is 0.46×10-20cm2 with the emission band width of 85 nm, even broader than the well-known Yb:CaGdAlO4. It has quite a high thermal conductivity of 5.54W/(m⋅K) at 50°C, comparable with Yb:YAG. In the continuous-wave regime, the maximum output power of 13.45 W at 1063.9 nm was generated with the optical-to-optical efficiency of 63.3%. These results suggest that the Yb:GdScO3 crystal is a promising candidate for ultrashort pulse lasers.

Anisotropy in spectroscopic and laser properties of Yb:Sr_3La_2(BO_3)_4 disordered crystal

We report, for the first time to our knowledge, on the polarized absorption and emission spectra and efficient laser action of the Yb:Sr3La2(BO3)4 disordered crystal. The strongest absorption and emission occur at about 977 nm for polarization direction parallel to the crystallographic b axis, with the peak absorption and emission cross-sections amounting, respectively, to 1.95 × 10−20 and 2.45 × 10−20 cm2. Efficient continuous-wave laser action is demonstrated with a-, b-, and c-cut crystal samples longitudinally pumped by a 976-nm diode laser, producing an output power of up to 8.2 W with an optical-to-optical efficiency of 32% with respect to incident pump power. Depending on the output coupling utilized, the laser action could exhibit a transition from single-polarization oscillation to dual-orthogonal-polarization oscillation at a certain pump level.

Spectral and Laser Properties of Yb:LuAG Transparent Ceramics Fabricated by Tape Casting Method

Yb3+‐doped LuAG laser ceramics with different Yb3+‐doping concentrations were successfully fabricated by nonaqueous tape casting method and vacuum sintering technology. XRD patterns and SEM morphologies of the ceramics were presented. The optical in‐line transmittance of the Yb‐doped LuAG ceramics was about 83% at 1030 nm. The fluorescence lifetime of annealed and unannealed ceramic samples was compared. From the spectroscopic properties, it can be seen that the ceramics had a large emission cross section of 2.9 × 10−20 cm2 with a FWHM of about 7.2 nm at 1030 nm. Under 100% population inversion, the maximum gain coefficient was estimated to be 12.4 cm−1 at 1030 nm. With a fiber‐coupled diode laser as pump source, CW laser at 1030 nm was demonstrated and the maximum output power of 338.9 mW was achieved with a slop efficiency of 19%. A tuning range from 1028 to 1036 nm was obtained.

Characteristics of a diode-pumped Yb:CaF2–SrF2 mode-locked laser using a carbon nanotube absorber

Yb:CaF2–SrF2 disordered crystals are successfully grown by the TGT method. By using a double-walled carbon nanotube saturable absorber (DWCNT-SA), the continuous-wave mode-locked (CWML) laser properties of Yb:CaF2–SrF2 crystals are demonstrated under diode pumping for the first time. The mode-locked laser delivers pulses as short as 5 ps at a center wavelength of 1045.5 nm without any dispersion compensation. The oscillator operating at a repetition rate of ∼87 MHz delivers 292 mW average output power.

Spectral and laser properties of Yb and Ho co-doped (YLa)2O3 transparent ceramic

Highly transparent Yb, Ho doped (YLa)2O3 ceramic was fabricated by conventional ceramic processing with nanopowders. The absorption and emission spectra of the ceramic was investigated. The energy transfer mechanism between Yb3+ and Ho3+ was also discussed. The strong emission band around 2 μm indicated that the Yb—Ho: (Y0.90La0.10)2O3 transparent ceramic is a promising gain medium for the generation of 2 μm laser emissions. The laser operation of Yb—Ho co-doped (YLa)2O3 ceramic at 2.1 μm is first reported.

Thermal and laser properties of Yb:LuAG for kW thin disk lasers

Thin disk laser experiments with Yb:LuAG (Yb:Lu(3)Al(5)O(12)) were performed leading to 5 kW of output power and an optical-to-optical efficiency exceeding 60%. Comparative analyses of the laser relevant parameters of Yb:LuAG and Yb:YAG were carried out. While the spectroscopic properties were found to be nearly identical, investigations of the thermal conductivities revealed a 20% higher value for Yb:LuAG at Yb(3+)-doping concentrations of about 10%. Due to the superior thermal conductivity with respect to Yb:YAG, Yb:LuAG offers thus the potential of improved performance in high power thin disk laser applications.

Anisotropy in spectroscopic and laser properties of monoclinic Yb:KLu(WO4)2 crystal

We conducted an investigation into the polarized absorption and emission spectra, the absorption for unpolarized pump light, and the continuous-wave (cw) laser properties of the Yb:KLu(WO4)2 crystal. The low symmetry of the crystal leads to strong anisotropy in the crystal spectroscopy; the strongest absorption and emission occur in the polarization direction parallel to the Nm principal axis. The Ng-cut crystal has highest absorption efficiency for unpolarized pump light and largest potential for generating laser output power. With 11 W of cw output power produced by using a 2 mm thick crystal, the optical-to-optical conversion and slope efficiencies amount to 68% and 80%, respectively, with respect to the absorbed pump power.

Temperature-dependent lasing and spectroscopy of Yb:Y 2O 3 and Yb:Sc 2O 3

Spectroscopic and laser properties of Yb 3+ in ceramic Y 2O 3 have been studied at room and cryogenic temperatures. Laser performance is very substantially improved by cooling to liquid nitrogen temperature, primarily due to the great reduction in ground state absorption that permits laser operation on the much stronger 1030-nm emission line rather than the 1077-nm line. The 976-nm “zero line” is observed to become much weaker as the temperature is reduced. Several models for this behavior are considered, but none adequately explains this surprising result. Spectroscopy of Yb:Sc 2O 3 indicates that it is likely to be an even better cryogenic gain material, given samples of comparable optical quality.

Growth, spectroscopic, and laser properties of Yb^3+-doped Lu_3Al_5O_12 garnet crystal

We have grown high-quality LuAG:Yb3+ crystals with 0.75, 3.8, 10, 12, 15, 20, and 50 at. % concentrations by the vertical Bridgman method. With low-temperature spectroscopy the Stark sublevel structure of the 2F7/2 ground state and the 2F5/2 excited state has been determined. With room-temperature spectroscopy, the emission cross section was found to be 3×10−20 cm2, being 1.5 times the YAG:Yb3+ emission cross section. The luminescence quantum efficiency was measured in samples with different Yb3+ concentrations. Its value was found to be 90% for 3.8 and 10 at. %, 84% for 20 at. %, and 70% for 50 at. % Yb3+. The laser-emission tunability under diode pumping was found to extend from 1045 up to 1095 nm in a 12 at. % sample with 3.15 mm thickness.

Thermal stability, spectra and laser properties of Yb:lead-zinc-lanthanum-tel lurite glasses

A series of new glasses of 70TeO22-(20-x) ZnO-xPbO-5La22O33-25K22O-25Na22O (x=0,5,10,15, 20mol %) doped with Yb22O33 is presented. Thermal stability, spectra and laser properties of Yb3+3+ ions have been measured. It has been found that the glass with x=15 has a good thermal s tability ((Txx-Tgg)>195℃), high stimulated emission cross -section of 125pm22 for the 22F5/25/2 →22F7/27/2 transition and a long fluorescence lifetime of 094ms and a broad fluorescence effective linewidth of 72nm. From the viewpoint of good potential laser parameters, it is desirab le to have high-average power and short pulse tunable laser, which can be achie ved by doping with Yb22O33.

Thermal stability, spectra and laser properties of Yb: lead–zinc–telluride oxide glasses

A series of new glasses of 70TeO 2–(20 − x) ZnO– xPbO − 5La 2O 3–2.5K 2O–2.5Na 2O (mol%) doped with Yb 3+ is presented. Thermal stability, spectra and laser properties of Yb 3+ ions have been measured. It found that 70TeO 2–15PbO–5ZnO–5La 2O 3–2.5K 2O–2.5Na 2O composition glass had fine stability (( T x− T g)>190 °C), high-stimulated emission cross-section of 1.25 pm 2 for the 2F 5/2 → 2F 7/2 transition and existed measured fluorescence lifetime of 0.94 ms and the broad fluorescence effective linewidth of 72 nm. Evaluated from the good potential laser parameters, this system glass is excellent for short pulse generation in diode pumped lasers, short pulse generation tunable lasers, high-peak power and high-average power lasers.

Thermal analysis, spectra and laser properties of a new Yb 3+-doped multicomponential tellurite-based glass

A series of new glasses of 70TeO 2-(20− x) ZnO– xGeO 2–5La 2O 3–2.5K 2O–2.5Na 2O (mol%) doped with Yb 3+ is presented. Thermal analysis, spectra and laser properties of Yb 3+ ions have been measured. It is found that 70TeO 2–20GeO 2–5La 2O 3–2.5K 2O–2.5Na 2O composition glass had better thermal stability than 75TeO 2–20ZnO–5Na 2O glass, higher stimulated emission cross-section of 1.23 pm 2 for the 2 F 5/2→ 2 F 7/2 transition close to PN glass, lower minimum pump intensity of 0.98 KW/cm 2 , long fluorescence lifetime of 0.92 ms and the broad fluorescence effective line width of 77 nm . Evaluated from the good potential laser parameters, this system glass is a promising host of miniature solid lasers such as short pulse generation in diode pumped lasers, short pulse generation tunable lasers, high-peak power and high-average power lasers, etc.

Thermal and laser properties of Yb:YAl 3(BO 3) 4 crystal

Large optical-quality Yb:YAl 3(BO 3) 4(Yb:YAB) crystals have been grown by the flux method. The thermal properties of Yb:YAB crystal were measured for the first time. The thermal properties of Yb:YAB crystal with different Yb 3+ ion concentrations are also reported. The results show that the ytterbium concentration influences the properties of Yb:YAB crystal. The specific heat decreases with the increase of Yb 3+ ion concentrations in the experiment range. Apparently, the thermal expansion coefficient increases along the c-direction with the increase of Yb 3+ ion concentrations, while it changes slightly along the a-direction. The output laser in 1120–1140 nm ranges has been demonstrated pumped by InGaAs laser. The slope efficiency is 3.8%. The self-frequency-doubling output power of 1 mW is achieved.

Optical and laser properties of Yb:Y2SiO5 single crystals and discussion of the figure of merit relevant to compare ytterbium-doped laser materials

In this paper, we explore two different directions in the investigation of Yb-doped solid-state laser crystals. At first, we describe the spectroscopic properties, site occupancies, energy-level diagrams and laser performances of Yb:Y2SiO5 (Yb:YSO), a new promising laser material. Then, in a more general point of view, we discuss the problem of evaluating the laser potential of the known Yb-based lasers. The approach proposed by De Loach et al. [IEEE J. Quantum Electron. 29 (1993) 1179] is shown to be incomplete to some extent. In a search for new figures of merit, it seems reasonable to include other parameters such as the thermal properties of the host.

Diode pumping and laser properties of Yb:Ho:YAG

The rare-earth ion Yb 3+ is an efficient sensitizer for Ho 3+ crystal lasers. It has a broad absorption band lying in the emission range of commercially available InGaAs diode lasers and an efficient energy transfer to Ho 3+. We have investigated four Yb 3+:Ho 3+:YAG laser crystals with 16.1 and 30.3 at.% Yb 3+, both with 2 at.% Ho 3+ and two different crystal thicknesses. The pump absorption coefficient α is about 15.1 cm −1 for 16.1 at.% Yb 3+ in YAG at λ=936 nm. Due to the strong absorption, relatively thin crystals with a thickness of 0.5 and 1 mm were used in active mirror configuration. Room temperature cw laser emission has been achieved in all these crystals. The laser thresholds have been measured as a function of the crystal temperature between 0 and 60°C. Thresholds and slope efficiencies of the different crystals are compared. Under diode laser pumping room temperature quasi cw emission up to 370 mW has been achieved in a 15-mm-long resonator for the first time.