Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of the Optical Society of America B

Laser cooling in Yb^3+:YAG

Galina A. Nemova, Raman Kashyap

Published Jan 22, 2014• 20 citations
Publisher

Abstract

We develop a detailed theoretical model for laser cooling in Yb3+:YAG. The expressions for the fluorescence power density removed from the system with spontaneous emission, the power density radiated with stimulated emission, as well as the heat power density generated in the system by nonradiative decays on the impurities of the host material have been calculated. The influence of each of these power densities on the cooling process has been analyzed. We show, for the first time to our knowledge, how the temperature dependences of the different parameters of the system as well as the concentration of the impurities in the host influence the final temperature of the cooled sample.

DOI
10.1364/josab.31.000340

Related papers

Temperature dynamics of laser cooling of solids with Yb3+ions

Galina A. Nemova, Raman Kashyap

We consider a theoretical model for laser cooling with anti-Stokes fluorescence of a Yb3+:YAG sample. We have estimated the fluorescence power density removed from the system with spontaneous emission, the power density radiated with stimulated emission as well as the heat power density generated in the system by non-radiative decays from the impurities in the host material. We have investigated the influence of each of these power densities on the cooling process in Yb3+:YAG system. It has been shown how the temperature dependences of the different parameters of the system as well as the concentration of the impurities in the host influence the final temperature of the cooled sample.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Feb 19, 2014•1 citation

Minimization of temperature for laser cooling of Yb-ion-doped crystals

Andrei V. Ivanov, Yu. Rozhdestvensky, E. Yu. Perlin

In this paper, quantum mechanical calculations of cooling characteristics for the Yb3+: YLF system with use of the vibronic model of laser cooling are presented. Dynamics of the laser cooling process for the seven-level system of an Yb ion is described by the density-matrix formalism. Dependences of the cooling characteristics on the pump intensity are obtained for various temperatures and absorption coefficients of impurity ions. It is shown that the pump intensity, at which the net cooling power has a maximum, depends on temperature. Thus, choosing the intensities, which correspond to the net cooling power maximum over the entire temperature range, we achieve a lower sample temperature at a shorter time than in the case of using a constant intensity throughout the cooling process. Calculations are performed for the parameters of the Yb3+:YLF system.

Applied Optics•Sep 19, 2016•4 citations

Research on several parameters influencing on laser cooling of solids

Jia You-Hua, Ji Xian-Ming, Yin Jian-Ping +1 more

Laser cooling of solids is also called anti-Stokes fluorescent cooling, it is a new optical cooling technology in recent years. We propose a two-level model to analyze the absorption and stimulated-emission processes between the Yb3+2F7/2 ground-state manifold and the 2F5/2 excited-state manifold, and discuss several parameters that influence the cooling power, and find some ways to improve the cooling power. The influences of the doped concentration, pumping power and the effective pump-spot area on cooling are particularly analyzed. At the same time, we make computer simulation about the cooling process and obtain the temperature as a function of the cooling time, which is similar to the experimental results. So this shows that our model is reasonable.

Acta Physica Sinica•Jan 1, 2007•1 citation

Comparison of Yb3+: YAP with Yb3+: YAG cooling crystals

Chaoyu Wang, Jianping Yin

Abstract YAlO 3 (YAP) shows lower phonon energy than Y 3 Al 5 O 12 (YAG), which implies a lower temperature can be obtained in Yb 3+ -doped YAP according to the single-frequency phonon model. Here, a 2% Yb 3+ : YAP crystal was refrigerated by anti-Stokes fluorescence and compared to YAG crystal with the same doping concentration in experiments. Yb 3+ exhibited a broad spectral cooling range in YAP from 1020nm to 1070nm, which was broader than in YAG from 1020 nm to 1055 nm. A minimum achievable temperature (MAT) dropped to ~ 249.7 K at 1040 nm for Yb 3+ : YAP, which was lower than that of ~ 259.3 K obtained in 2% Yb 3+ : YAG. Further analysis predicted that the cooling limit of two crystals can reach ~167 K for Yb 3+ : YAP and ~171 K for Yb 3+ : YAG from room temperature. This work exhibited the excellent cooling properties of Yb 3+ : YAP compared with Yb 3+ : YAG in experiment and provided a unique perspective for the practical application of high-power Radiation balance lasers (RBLs).

Applied Physics B•Apr 27, 2026•1 citation

Saturation Effects and Thermal Balance in Laser-Cooled Solids

Long Cheng

The role of saturation of background absorption by unintended impurities has been investigated for the first time theoretically and experimentally in the context of laser cooling of crystalline solids and the operation of self-cooled or radiation-balanced lasers. In this thesis it is shown that when saturation of the background takes place at an intensity lower than the saturation intensity of dopant ions responsible for cooling, as in Yb3+:LiYF4, cooling efficiency can be improved by using elevated input intensity. With the same input power, the measured cooling efficiency in 10% Yb3+:LiYF4 crystal was doubled at 1020 nm when the beam radius was reduced by a factor of 10, by partially saturating the background impurity absorption. This is effective not only as a post-growth method of enhancing cooling efficiency but offers a new way of reaching lower temperatures than were previously possible with anti-Stokes fluorescent (ASF) refrigeration. Prior to this work, cooling efficiency was thought to be independent of intensity and crystal purification was considered as the only way to improve the cooling efficiency. It is further demonstrated that background saturation plays a key role in the operation of self-cooled or radiation-balanced lasers. Because radiation-balanced lasers operate under saturated conditions it is essential to include limitations imposed by impurity content of the gain medium. When this is done, quantitative predictions of the required conditions for radiation balance become possible. Laser operation can then be made more efficient and can be extended to new materials which may be relatively impure and uncommon but are well-suited to efficient operation under radiation-balanced conditions by virtue of a special combination of physical characteristics. Radiation-balanced laser operation is achieved in 3% Yb:YAG (1 × 1 × 10 mm3) and is found to result in exceptionally uniform temperature distributions using high resolution thermal imagery. Threshold levels, output power, and input power at the radiation balance point are all shown to be in close agreement with theory. This laser achieved 30.5% laser efficiency (agreed with predictions within 2%), which is the highest efficiency level of any self-cooled laser operated to date. Radiation-balanced lasing is also achieved for the first time in the tungstate crystal 2% Yb3+:KYW (0.9×1.2×10 cm3), despite having very high impurity content as the result of being an uncommon gain medium. The achieved laser efficiency was only 2.2%, as the result of non-optimal optical components, high Yb concentration, high impurity content, crystal polish, excitation wavelength, and output coupling. However, this is the first demonstration of an Yb3+ radiation-balanced laser in the tungstate host. Correction of these deficiencies should enable high quality Gaussian output at the 5 W level with 18% efficiency in existing commercial 1% Yb:KYW samples. Even better performance of this new self-cooled laser could result from improved crystal growth efforts.

•Jan 1, 2023•0 citations

Nonlinear Decay of the Excited State in Yb:YAG

Mikhail Larionov, Karsten Schuhmann, Jochen Speiser +2 more

Decay processes depending on the density of the excited Yb -ions and the temperature with a rate comparable to spontaneous fluorescence rate are observed in Yb:YAG. Their rate and the additional heat generation are estimated.

Advanced Solid-State Photonics (TOPS)•Jan 1, 2005•29 citations
We develop a detailed theoretical model for laser cooling in Yb3+:YAG. The expressions for the fluorescence power density removed from the system with spontaneous emission, the power density radiated with stimulated emission, as well as the heat power density generated in the system by nonradiative decays on the impurities of the host material have been calculated. The influence of each of these power densities on the cooling process has been analyzed. We show, for the first time to our knowledge, how the temperature dependences of the different parameters of the system as well as the concentration of the impurities in the host influence the final temperature of the cooled sample.
We consider a theoretical model for laser cooling with anti-Stokes fluorescence of a Yb3+:YAG sample. We have estimated the fluorescence power density removed from the system with spontaneous emission, the power density radiated with stimulated emission as well as the heat power density generated in the system by non-radiative decays from the impurities in the host material. We have investigated the influence of each of these power densities on the cooling process in Yb3+:YAG system. It has been shown how the temperature dependences of the different parameters of the system as well as the concentration of the impurities in the host influence the final temperature of the cooled sample.
In this paper, quantum mechanical calculations of cooling characteristics for the Yb3+: YLF system with use of the vibronic model of laser cooling are presented. Dynamics of the laser cooling process for the seven-level system of an Yb ion is described by the density-matrix formalism. Dependences of the cooling characteristics on the pump intensity are obtained for various temperatures and absorption coefficients of impurity ions. It is shown that the pump intensity, at which the net cooling power has a maximum, depends on temperature. Thus, choosing the intensities, which correspond to the net cooling power maximum over the entire temperature range, we achieve a lower sample temperature at a shorter time than in the case of using a constant intensity throughout the cooling process. Calculations are performed for the parameters of the Yb3+:YLF system.
Laser cooling of solids is also called anti-Stokes fluorescent cooling, it is a new optical cooling technology in recent years. We propose a two-level model to analyze the absorption and stimulated-emission processes between the Yb3+2F7/2 ground-state manifold and the 2F5/2 excited-state manifold, and discuss several parameters that influence the cooling power, and find some ways to improve the cooling power. The influences of the doped concentration, pumping power and the effective pump-spot area on cooling are particularly analyzed. At the same time, we make computer simulation about the cooling process and obtain the temperature as a function of the cooling time, which is similar to the experimental results. So this shows that our model is reasonable.
Abstract YAlO 3 (YAP) shows lower phonon energy than Y 3 Al 5 O 12 (YAG), which implies a lower temperature can be obtained in Yb 3+ -doped YAP according to the single-frequency phonon model. Here, a 2% Yb 3+ : YAP crystal was refrigerated by anti-Stokes fluorescence and compared to YAG crystal with the same doping concentration in experiments. Yb 3+ exhibited a broad spectral cooling range in YAP from 1020nm to 1070nm, which was broader than in YAG from 1020 nm to 1055 nm. A minimum achievable temperature (MAT) dropped to ~ 249.7 K at 1040 nm for Yb 3+ : YAP, which was lower than that of ~ 259.3 K obtained in 2% Yb 3+ : YAG. Further analysis predicted that the cooling limit of two crystals can reach ~167 K for Yb 3+ : YAP and ~171 K for Yb 3+ : YAG from room temperature. This work exhibited the excellent cooling properties of Yb 3+ : YAP compared with Yb 3+ : YAG in experiment and provided a unique perspective for the practical application of high-power Radiation balance lasers (RBLs).
The role of saturation of background absorption by unintended impurities has been investigated for the first time theoretically and experimentally in the context of laser cooling of crystalline solids and the operation of self-cooled or radiation-balanced lasers. In this thesis it is shown that when saturation of the background takes place at an intensity lower than the saturation intensity of dopant ions responsible for cooling, as in Yb3+:LiYF4, cooling efficiency can be improved by using elevated input intensity. With the same input power, the measured cooling efficiency in 10% Yb3+:LiYF4 crystal was doubled at 1020 nm when the beam radius was reduced by a factor of 10, by partially saturating the background impurity absorption. This is effective not only as a post-growth method of enhancing cooling efficiency but offers a new way of reaching lower temperatures than were previously possible with anti-Stokes fluorescent (ASF) refrigeration. Prior to this work, cooling efficiency was thought to be independent of intensity and crystal purification was considered as the only way to improve the cooling efficiency. It is further demonstrated that background saturation plays a key role in the operation of self-cooled or radiation-balanced lasers. Because radiation-balanced lasers operate under saturated conditions it is essential to include limitations imposed by impurity content of the gain medium. When this is done, quantitative predictions of the required conditions for radiation balance become possible. Laser operation can then be made more efficient and can be extended to new materials which may be relatively impure and uncommon but are well-suited to efficient operation under radiation-balanced conditions by virtue of a special combination of physical characteristics. Radiation-balanced laser operation is achieved in 3% Yb:YAG (1 × 1 × 10 mm3) and is found to result in exceptionally uniform temperature distributions using high resolution thermal imagery. Threshold levels, output power, and input power at the radiation balance point are all shown to be in close agreement with theory. This laser achieved 30.5% laser efficiency (agreed with predictions within 2%), which is the highest efficiency level of any self-cooled laser operated to date. Radiation-balanced lasing is also achieved for the first time in the tungstate crystal 2% Yb3+:KYW (0.9×1.2×10 cm3), despite having very high impurity content as the result of being an uncommon gain medium. The achieved laser efficiency was only 2.2%, as the result of non-optimal optical components, high Yb concentration, high impurity content, crystal polish, excitation wavelength, and output coupling. However, this is the first demonstration of an Yb3+ radiation-balanced laser in the tungstate host. Correction of these deficiencies should enable high quality Gaussian output at the 5 W level with 18% efficiency in existing commercial 1% Yb:KYW samples. Even better performance of this new self-cooled laser could result from improved crystal growth efforts.