Emission Cross Section Of Yb Research Articles

Temperature-dependent radiative lifetime of Yb:YLF: refined cross sections and potential for laser cooling

We revisit the spectroscopic characterization of ytterbium-doped LiYF4 (Yb:YLF) for the application of laser cooling. Time-dependent fluorescence spectroscopy reveals a temperature dependence of the radiative lifetime which we explain by the Boltzmann distribution of excited ions in the upper Stark levels. The emission cross sections of Yb:YLF from 17 K to 440 K are revised using the temperature-dependent radiative lifetimes from fluorescence spectra. We provide fit equations for the peak values of important transitions as a function of temperature, which is also useful for the design of Yb:YLF laser oscillators and amplifiers operated at cryogenic temperatures. Based on our spectroscopic data, we show the prerequisite crystal purity to achieve laser cooling below liquid nitrogen temperatures.

Fabrication and spectral properties of Yb,Ho:Y2O3 transparent ceramics

Yb,Ho:Y 2 O 3 ceramics have been fabricated by Spark Plasma Sintering method (SPS). The microstructure and transmittance of the ceramics sintered from 1623 K to 1673 K were analyzed. The highest in-line transmittance of Yb,Ho:Y 2 O 3 ceramic sintered at 1673 K reached almost 83% at 750 nm with the thickness of 1 mm. The absorption spectra, fluorescence spectra and fluorescence decay curve were recorded at room temperature. The Judd-Ofelt parameters Ω 2 , Ω 4 and Ω 6 were calculated to be 8.33 × 10 −20 cm 2 , 1.81 × 10 −20 cm 2 , and 0.82 × 10 −20 cm 2 , respectively. The intense emission cross section of Yb,Ho:Y 2 O 3 ceramic was 3.43 × 10 −20 cm 2 at 2057 nm with full width at half maximum (FWHM) of 208 nm. The results indicate that Yb,Ho:Y 2 O 3 transparent ceramic can be a promising laser gain medium for laser operation around 2 μm. • The highest in-line transmittance of Yb,Ho:Y 2 O 3 ceramic sintered at 1673 K reached almost 83% at 750 nm with the thickness of 1 mm. • The spectral characteristics were intensively investigated through Judd-Ofelt theory.

Radiative transition properties of Yb3+ in Er3+/Yb3+ co-doped NaYF4 phosphor

Usually, it is difficult to quantitatively express the optical transition properties of Yb 3+ in powdered samples owing to the difficulty in measuring the absolute absorption spectra. In this work, we developed an approach for confirming the absorption and emission cross section spectra and the radiative transition rates for the absorption and emission transitions between 2 F 7/2 and 2 F 5/2 states of Yb 3+ . The proposed approach was examined for Yb 3+ in Er 3+ /Yb 3+ co-doped NaYF 4 powders. The absorption cross section for 2 F 7/2 → 2 F 5/2 transition and emission cross section for 2 F 5/2 → 2 F 7/2 transition of Yb 3+ in NaYF 4 :Er 3+ /Yb 3+ were confirmed. Meanwhile, the transition rates for the absorption and emission transitions were also calculated. A route for calculating the radiative transition rate, absorption and emission cross sections of Yb 3+ in powdered samples is proposed. Furthermore, the radiative transition properties of Yb 3+ in NaYF 4 :Er 3+ /Yb 3+ phosphor derived from an auto-combustion-assisted fluoridation was studied via our proposed route. • NaYF 4 : Er 3+ and NaYF 4 : Er 3+ /Yb 3+ phosphors were prepared via an auto-combustion assisted solid-state reaction. • A new calculation method of radiation transition rates of Yb 3+ was proposed and used for Er 3+ /Yb 3+ co-doped NaYF 4 powders. • The absorption cross section spectra of Er 3+ /Yb 3+ co-doped NaYF 4 and Er 3+ doped NaYF 4 powders were confirmed. • The absorption and emission cross sections of Yb 3+ in NaYF 4 were derived. • The transition rates of Yb 3+ for the absorption ( 2 F 7/2 → 2 F 5/2 ) and emission ( 2 F 5/2 → 2 F 7/2 ) transitions were calculated.

Transition intensity calculation of Yb:YAG**Project supported by the National Natural Science Foundation of China (Grant Nos. 61405206, 51502292, and 51702322), the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant Nos. CXJJ-16M251 and CXJJ-15M055), and the National Key Research and Development Program of China (Grant No. 2016YFB0402101)

The Yb:YAG is an excellent high-average power and ultra-short pulse laser crystal. Transition intensity parameters and Huang–Rhys factors are fitted to its emission spectrum by the full-profile fitting method. Calculated results indicate that the emission spectrum of Yb:YAG at cryogenic temperature consists of three pure electron state transitions and two phonon-assisted transitions, one vibronic transition releases one-phonon of 3 cm−1, and the other vibronic transition absorbs one-phonon of 22 cm−1. At 300 K, the phonon assisted transition of 3 cm−1 turns into two- or more-phonon assisted transitions. The procedure absorbing phonon can reduce the thermal load of Yb:YAG and improve the laser efficiency, which may be one of the reasons why Yb:YAG has excellent performance. The emission bands of Yb:YAG are broadened thermally, and the peak values decrease by several times. The emission cross sections of Yb:YAG determined by Fuchtbauer–Ladenburg (F–L) formula are remarkably different from those calculated with , which indicates that it is necessary for a laser material to determine its transition intensity parameters in order to reasonably evaluate the laser performance.

Growth, structure, and spectroscopic properties of 5 at.% Yb:GdNbO4 laser crystal

A new crystal of Yb-doped gadolinium niobate, 5at.% Yb:GdNbO4, is grown by Czochralski method for the first time. The structure of Yb:GdNbO4 is determined by Rietveld refinement to the X-ray powder diffraction data and it belongs to the monoclinic space group of I2/a. With the center of 955nm, the FWHM of absorption spectra is 57nm and the absorption cross section is calculated to be 0.97×10−20cm2. Spectral parameters are calculated with absorption spectrum. In emission spectra, the strongest peak is at 1001nm and the FWHM is 49nm. In comparison with corresponding emission cross section of Yb:YSO and Yb:GSO, Yb:GdNbO4 exhibits a relatively larger emission cross section. In addition, a maximal output power of 270mW is obtained and the slope efficiency is 7.5%.

Phosphate Yb3+ doped air-cladding photonic crystal fibers for laser applications

We present two single-mode photonic crystal fibers with air-cladding for laser applications. We developed PCF structures created by replacing respectively one and seven air-holes with 6%mol ytterbium doped glass. With increasing mode area you can increase power level and shorten fiber length in laser construction. We achieved 53 and 19 cm optimum length fiber lasers with 4.7 W and 12.4 W respectively maximum output power. The slope efficiency of the lasers were 15.6% and 42.4%. The use of air-cladding brought very high numerical aperture of pump waveguides in both laser fibers resulting with the value of 0.72 and 0.91 respectively. Full Text: PDF References J. Limpert, O. Schmidt, J. Rothhartd, F. Röser, T. Schreiber, A. Tunnermann, "Extended single-mode photonic crystal fiber lasers", Opt. Express 14, 2715 (2006), CrossRef G. Bouwmans, R. M. Percival, W. J. Wadsworth, J. C. Knight, P. St. J. Russell, "High-power Er:Yb fiber laser with very high numerical aperture pump-cladding waveguide", Appl. Phys. Lett. 83, 817 (2003) CrossRef Y. Yeong, J. K. Sahu, D. N. Payne, J. Nilsson, "Ytterbium-doped large-core fiber laser with 1.36 kW continuous-wave output power", Opt. Express 12, 6088 (2004), CrossRef H.Yin, P. Deng, Y. Zhang, F. Gan, "Determination of emission cross section of Yb 3+ in glasses by the reciprocity method", Mat.Lett. 30, 29 (1997) CrossRef D.E. McCumber, "Theory of Phonon-Terminated Optical Masers", Phys. Rev. 134, 299 (1964) CrossRef D.E. McCumber, "Einstein Relations Connecting Broadband Emission and Absorption Spectra", Phys. Rev. 136, 954 (1964) CrossRef L. Li et al., "Investigation of modal properties of microstructured optical fibers with large depressed-index cores", Opt. Lett. 30, 3275 (2005) CrossRef W. J. Wadsworth et al.,"Very high numerical aperture fibers", Photonics Techn. Lett. 16, 843 (2004) CrossRef L. Zenteno, J.Lightwave Techn. 11, 1435 (1993) Y. Lee, M. J. F. Digonnet, S. Sinha, KE. Urbanek, R. L. Byer, S. Jiang, JSQE 1, 93 (2009)

Experimental Study on Temperature Dependence of Absorption and Emission Properties of Yb:YAG Crystal as a Disk Laser Medium

In this paper, the absorption and fluorescence emission spectra of Yb:Y3Al5O12 (YAG)(25 at%) crystal as a disk laser medium are measured at high temperature (300-450K). The absorption and emission cross sections of Yb:YAG crystal are determined using Reciprocity method. Temperature dependence of 941nm absorption cross section and 1031nm emission cross section is extracted in the range of 300-450K. According to our experimental results, an exponential temperature dependence between 300K and 450K is acquired for the 1031nm peak emission cross section and also for 941nm peak absorption cross section of Yb:YAG crystal. These results could be used for simulation and design of high power highly doped Yb:YAG thin disk lasers. Keywords—Yb:YAG crystal, Emission cross section, Absorption coefficient, Temperature dependence, Reciprocity method .

Fluorescence investigation of Ho 3+ in Yb 3+ sensitized mixed-alkali bismuth gallate glasses

Efficient 2.0 μm infrared and visible upconversion emissions have been observed in Ho 3+/Yb 3+ co-doped mixed-alkali bismuth gallate (LKBBG) glasses having a maximum-phonon energy of 673 cm −1. The Judd–Ofelt parameters Ω 2, Ω 4 and Ω 6 of Ho 3+ indicate that there is a high asymmetry and strong covalent environment in LKBBG glasses. The large absorption and emission cross-sections of Yb 3+ confirm that it is a suitable sensitizer for capturing and transferring pump energy to Ho 3+. The emission cross-section profile for the 5I 7 → 5I 8 transition is derived using the reciprocity method and the peak value is 5.54 × 10 −21 cm 2, which is much larger than the value in fluorozircoaluminate glasses. LKBBG glasses exhibit low maximum-phonon energy and large refractive index, and it is possible to achieve an effective 1.66 μm U-band emission of Ho 3+ under 900nm laser radiation.

Dependence of the Yb^3+ emission cross section and lifetime on temperature and concentration in yttrium aluminum garnet

Measurements are reported of the spectroscopic properties (absorption and emission spectra, stimulated-emission cross section, and radiative lifetime) of (YbxY1-x)3Al5O12 for nominal x values of 0.025, 0.05, 0.1, 0.2 and 0.3 at temperatures of 15–300 K. The emission cross sections of Yb:YAG with different Yb3+ concentrations were determined by use of the Füchtbauer–Ladenburg formula and the reciprocity method. At low temperatures, the product (στ) of the effective stimulated-emission cross section and the radiative lifetime is greater than at room temperature for all concentrations. Product στ is nearly independent of Yb3+ concentration at a given temperature. These results will aid in the design of high-power thin disk lasers by use of highly doped Yb:YAG.

Determination of emission cross section of Yb 3+ in glasses by the reciprocity method

The reciprocity method is applied to calculate the emission cross section of Yb 3+ in glasses, the error in σ em being less than ± 15%. The effect of radiation trapping is quantitatively evaluated by the parameter [( I p I S ) c − ( I p I s ) m]/( I p I s ) c, and fluorescence lifetime is determined by the equation τ f = τ m( I p I s ) m ( I p I s ) c .