Anti-Stokes regime of laser cooling of solids

2000 ◽  
Author(s):  
Sergei N. Andrianov ◽  
Vitaly V. Samartsev
Keyword(s):  
Laser Cooling ◽  
Anti Stokes

Anti-Stokes laser cooling in Yb^3+-doped KPb_2Cl_5 crystal

2002 ◽  
Vol 27 (17) ◽  
pp. 1525 ◽  
Author(s):  
A. Mendioroz ◽  
J. Fernández ◽  
M. Voda ◽  
M. Al-Saleh ◽  
R. Balda ◽  
...  
Keyword(s):  
Laser Cooling ◽  
Anti Stokes

Enhanced Laser Cooling of Ion-Doped Nanopowders

2005 ◽  
Author(s):  
Xiulin Ruan ◽  
Massoud Kaviany
Keyword(s):  
Laser Cooling ◽  
Transition Rate ◽  
Dopant Concentration ◽  
Model Material ◽  
Photon Absorption ◽  
Nanocrystalline Powders ◽  
Field Energy ◽  
Cooling Power ◽  
Rare Earth Ion ◽  
Anti Stokes

Enhanced laser cooling performance of rare-earth ion doped nanocrystalline powders is predicted, using Yb3+:Y2O3 as the model material. This is achieved by enhancing the anti-Stokes off-resonance absorption, which is proportional to the three factors considered in this paper: dopant concentration, pumping field energy, and anti-Stokes transition rate. The concept of the optimum dopant concentration for cooling is proposed based on the fact that higher concentration increases absorption while decreases quantum efficiency. Using the concentration quenching theory of energy transfer, the optimum concentration, which gives the maximum cooling power, is found to be larger than the currently used value, suggesting noticeable enhancement effects for laser cooling. The pumping field energy is enhanced in random nanopowders compared with bulk crystals under the same irradiation, due to the multiple scattering of photons. Photons are thus localized in the medium and do not propagate through, increasing the photon absorption of the pumping beam. This also contributes significantly to laser cooling enhancement. Using molecular dynamics simulations, the phonon density of states (DOS) of the nanopowder is calculated, and found to have extended, small tails at low and high frequencies. The second-order electronic transition rate for the anti-Stokes luminescence is calculated using the Fermi golden rule, which includes the influence of this phonon DOS, and is shown to have enhancement effects on the laser cooling efficiency using nanopowders. Finally, it is concluded that these three enhancement mechanisms are exactly equivalent to increasing the number of the three participating carriers (electron, photon, and phonon) in the interacting volume.

scholarly journals Laser cooling of ytterbium-doped silica glass

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Esmaeil Mobini ◽  
Saeid Rostami ◽  
Mostafa Peysokhan ◽  
Alexander Albrecht ◽  
Stefan Kuhn ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Laser Cooling ◽  
Silica Glass ◽  
Radiative Decay ◽  
Laser Wavelength ◽  
Solid State Laser ◽  
Cooling Efficiency ◽  
Laser Applications ◽  
Anti Stokes ◽  
Rare Earth Doped

Abstract Laser cooling of a solid is achieved when a coherent laser illuminates the material in the red tail of its absorption spectrum, and the heat is carried out by anti-Stokes fluorescence of the blue-shifted photons. Solid-state laser cooling has been successfully demonstrated in several materials, including rare-earth-doped crystals and glasses. Here we show the net cooling of high-purity Yb-doped silica glass samples that are fabricated with low impurities to reduce their parasitic background loss for fiber laser applications. The non-radiative decay rate of the excited state in Yb ions is very small in these glasses due to the low level of impurities, resulting in near-unity quantum efficiency. We report the measurement of the cooling efficiency as a function of the laser wavelength, from which the quantum efficiency of the Yb-doped silica is calculated.

Advances in Laser Cooling of Solids

2006 ◽  
Vol 129 (1) ◽  
pp. 3-10 ◽  
Author(s):  
X. L. Ruan ◽  
M. Kaviany
Keyword(s):  
Laser Cooling ◽  
Nonradiative Recombination ◽  
Rapid Progress ◽  
Cooling Process ◽  
Theoretical Limit ◽  
Rare Earth Ion ◽  
Cooling Performance ◽  
Theoretical Predictions ◽  
Anti Stokes ◽  
Near Future

We review the progress on laser cooling of solids. Laser cooling of ion-doped solids and semiconductors is based on the anti-Stokes fluorescence, where the emitted photons have a mean energy higher than that of the absorbed photons. The thermodynamic analysis shows that this cooling process does not violate the second law, and that the achieved efficiency is much lower than the theoretical limit. Laser cooling has experienced rapid progress in rare-earth-ion doped solids in the last decade, with the temperature difference increasing from 0.3to92K. Further improvements can be explored from the perspectives of materials and structures. Also, theories need to be developed, to provide guidance for searching enhanced cooling performance. Theoretical predictions show that semiconductors may be cooled more than ion-doped solids, but no success in bulk cooling has been achieved yet after a few attempts (due to the fluorescence trapping and nonradiative recombination). Possible solutions are discussed, and net cooling is expected to be realized in the near future.

scholarly journals Anti-Stokes Laser Cooling in Bulk Erbium-Doped Materials

2006 ◽  
Vol 97 (3) ◽  
Author(s):  
Joaquin Fernandez ◽  
Angel J. Garcia-Adeva ◽  
Rolindes Balda
Keyword(s):  
Laser Cooling ◽  
Erbium Doped ◽  
Doped Materials ◽  
Anti Stokes

Plasmon Coupling - The Root Cause of Raman Anomaly and Laser Cooling in Nanocrystal Ge

2021 ◽  
Author(s):  
Manuchehr Ebrahimi ◽  
Amr Helmy ◽  
Nazir Kherani
Keyword(s):  
Laser Cooling ◽  
High Performance ◽  
Vibrational Energy ◽  
Plasmon Coupling ◽  
Optical Refrigeration ◽  
Electron Hole Plasma ◽  
Germanium Nanocrystals ◽  
Bandgap Semiconductors ◽  
Silicon And Germanium ◽  
Anti Stokes

Abstract Laser cooling of matter through anti-Stokes photoluminescence, where the emitted frequency of light exceeds that of the impinging laser by virtue of absorption of thermal vibrational energy, has been successfully realized in condensed media, and in particular with rare earth doped systems achieving sub-100K solid state optical refrigeration. Studies suggest that laser cooling in semiconductors has the potential of achieving temperatures down to ~10K and that its direct integration can usher unique high-performance nanostructured semiconductor devices. While laser cooling of nanostructured II-VI semiconductors has been reported recently, laser cooling of indirect bandgap semiconductors such as group IV silicon and germanium remains a major challenge. Here we report on the anomalous observation of dominant anti-Stokes photoluminescence in germanium nanocrystals principally associated with plasmon coupling. Specifically, we attribute this Raman anomaly to the confluence of ultra-high purity nanocrystal germanium, generation of high density of electron-hole plasma, the inherent degeneracy of longitudinal and transverse optical phonons in non-polar indirect bandgap semiconductors, and commensurate spatial confinement effects. At high laser intensities, plasmon-assisted laser cooling with lattice temperature as low as ~50K is inferred.

Development of an organic dye solution for laser cooling by anti-Stokes fluorescence

2001 ◽  
Vol 667 ◽  
Author(s):  
Jarett L. Bartholomew ◽  
Peter A. DeBarber ◽  
Bauke Heeg ◽  
Garry Rumbles
Keyword(s):  
Laser Cooling ◽  
Organic Dye ◽  
Quantum Yields ◽  
Long Wavelength ◽  
Fluorescence Quantum Yields ◽  
Optical Cooling ◽  
Doped Glasses ◽  
Anti Stokes ◽  
Rhodamine 101 ◽  
Dye Solutions

ABSTRACTSeveral independent groups have observed optical cooling by means of anti-Stokes luminescence in condensed media. The most promising materials are grouped into two categories: ion-doped glasses and organic dye solutions. It is this latter group that we focus our efforts on. Recent studies by our group show that irradiating a solution of rhodamine 101 in the long wavelength wing of the absorption spectrum results in the observation of optical cooling. To improve upon the initial observation of a few degree drop in temperature requires a better understanding of the conditions and phenomena leading to anti-Stokes luminescence in dye solutions. We develop a thermal lensing experiment to obtain fluorescence quantum yields of various dye solutions. The importance of concentration, choice of solvent, deuteration, and acidification are discussed.

Demonstration of Net Laser Cooling in a Semiconductor

2013 ◽  
Vol 02 (02) ◽  
pp. 27-28
Author(s):  
Dehui Li ◽  
Jun Zhang ◽  
Qihua Xiong
Keyword(s):  
Rare Earth ◽  
Laser Cooling ◽  
Energy Levels ◽  
Lattice Vibrations ◽  
High Crystalline Quality ◽  
Direct Band Gap ◽  
Doped Glasses ◽  
Direct Band ◽  
Anti Stokes ◽  
Rare Earth Doped

Laser cooling of solids was first proposed by Pringsheim in 1929, more than 30 years before the invention of laser. With the advantages of being compact and free of vibration and cryogen, the laser cooling of solids shows very promising applications such as all solid-state cryocoolers and atheraml lasers. The basic principle of laser cooling in solids is based on the anti-Stokes luminescence, during which the emitted photons carry more energy than the incident photons. The thermal energy contained in lattice vibrations in solids is carried away by the emitted photons during the anti-Stokes luminescence processes resulting in the cooling of solids. To achieve net laser cooling, there are very strict requirements for materials: high external quantum efficiency, high crystalline quality and properly spaced energy levels. So far, the materials suitable for laser cooling are confined to rare-earth doped glasses or direct band gap semiconductors due to those special requirements.

Solid-state laser cooling in Yb:CaF₂ and Yb:SrF₂ by anti-Stokes fluorescence

2021 ◽  
Author(s):  
Stefan Püschel ◽  
Felix Mauerhoff ◽  
Christian Kraenkel ◽  
Hiroki Tanaka
Keyword(s):  
Solid State ◽  
Laser Cooling ◽  
Solid State Laser ◽  
State Laser ◽  
Anti Stokes
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