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.

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.

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

Airship Piloting

1921 ◽  
Vol 25 (122) ◽  
pp. 47-93
Keyword(s):  
Atmospheric Conditions ◽  
Rapid Progress ◽  
Scientific Interest ◽  
The World ◽  
The Subject ◽  
Near Future

I feel it a great honour to have the privilege of addressing the members of the Royal Aeronautical Society on the subject of Airship Piloting, especially in view of the interest you have taken in furthering and generally assisting in the development of all types of aircraft.Although the airship has hitherto not occupied the thought and brains of Aeronautical Engineers to the same extent as the aeroplane and seaplane, I feel sure the confidence and support of the Society will lead to a more general and scientific interest being taken in lighter-than-air craft, which is bound to result in more rapid progress in the near future.I hope the discussion to follow will provide the foundation for solving some of the problems that will have to be faced, when piloting the airships over routes to various parts of the world, where totally different atmospheric conditions are likely to be encountered.

scholarly journals Introduction of a Portable and Non-invasive Technology for Hand and Foot Cooling: A Preclinical Feasibility Study

2021 ◽  
Author(s):  
Shirin Davarpanah Jazi ◽  
Johan Ralf ◽  
Mohammad FazelBakhsheshi
Keyword(s):  
Skin Temperature ◽  
Healthy Subjects ◽  
Cold Water ◽  
Healthy Individuals ◽  
Cooling Performance ◽  
Non Invasive ◽  
Reduced Dose ◽  
Before And After ◽  
Hands And Feet ◽  
Near Future

Abstract Purpose: Chemotherapy-induced peripheral neuropathy (CIPN) is caused by damage to neural structures in distal limbs. CIPN can lead to reduced dose or cessation of chemotherapy. Cooling the hands/feet has shown to be effective in reducing or preventing CIPN. However, when using ice bath or ice gloves/socks is no way to maintain the targeted temperature and prevent ice from melting. Also, patients have difficulty tolerating the freezing temperatures over long periods of chemotherapy. The aim of this study was to test the cooling performance of a recently developed non-invasive system that can ultimately replace current cooling methods.Methods: COOLPREVENT circulates cold water at tolerable temperatures into malleable gloves/socks. As well, COOLPREVENT does not require replacing of melted ice. We administered a cooling protocol via COOLPREVENT on three healthy subjects for 60 minutes. Immediately before and after cooling, skin temperature in the hands and feet were measured. Level of discomfort was also recorded during the cooling process.Results: Results showed that COOLPREVENT reduce skin temperature by 14.5±3.8°C and 10.7±1.7°C in the hands and feet, respectively within 60 minutes without significant discomfort.Conclusion: Although our study is limited by the small number of subjects and participation of healthy individuals, but we can conclude that COOLPREVENT can be a safe and appropriate method for hand and foot cooling. We hope that these preliminary findings can pave the way to designing clinical trials we plan to conduct in the near future.

scholarly journals Elusive super-hard B6C accessible through the laser-floating zone method

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Bibi Malmal Moshtaghioun ◽  
Francisco L. Cumbrera ◽  
Diego Gómez-García ◽  
Jose I. Peña
Keyword(s):  
High Pressures ◽  
Ceramic Materials ◽  
Critical Conditions ◽  
Floating Zone ◽  
Zone Method ◽  
Promising Alternative ◽  
Theoretical Predictions ◽  
Near Future ◽  
Laser Floating Zone Technique

Abstract Boron carbide is among the most promising ceramic materials nowadays: their mechanical properties are outstanding, and they open potential critical applications in near future. Since sinterability is the most critical drawback to this goal, innovative and competitive sintering procedures are attractive research topics in the science and technology of this carbide. This work reports the pioneer use of the laser-floating zone technique with this carbide. Crystallographic, microstructural and mechanical characterization of the so-prepared samples is carefully analysed. One unexpected output is the fabrication of a B6C composite when critical conditions of growth rate are adopted. Since this is one of the hardest materials in Nature and it is achievable only under extremely high pressures and temperatures in hot-pressing, the use of this technique offers a promising alternative for the fabrication. Hardness and elastic modulus of this material reached to 52 GPa and 600 GPa respectively, which is close to theoretical predictions reported in literature.

Laparoscopic Hepatectomy for Liver Cancer

2015 ◽  
Vol 33 (5) ◽  
pp. 691-698 ◽  
Author(s):  
Akishige Kanazawa ◽  
Tadashi Tsukamoto ◽  
Sadatoshi Shimizu ◽  
Satoshi Yamamoto ◽  
Akihiro Murata ◽  
...  
Keyword(s):  
Liver Cancer ◽  
Standard Procedure ◽  
Laparoscopic Hepatectomy ◽  
Surgical Techniques ◽  
Laparoscopic Approach ◽  
Technological Innovations ◽  
Rapid Progress ◽  
Hepatic Surgery ◽  
Novel Approach ◽  
Near Future

This chapter covers a range of important topics of laparoscopic hepatectomy as a novel approach toward treatment of liver cancer. Although laparoscopic hepatectomy was performed in a limited number of centers in the 1990s, technological innovations, improvements in surgical techniques and accumulation of experience by surgeons have led to more rapid progress in laparoscopic hepatectomy in the late 2000s for minimally invasive hepatic surgery. Currently, laparoscopic hepatectomy can be performed for all tumor locations and several diseases via several approaches. The laparoscopic approach can be applied to several types of resection, not only for tumors but also for liver transplantation, with equivalent or better results compared with those obtained with open surgery. Therefore, laparoscopic hepatectomy will become a standard procedure for treatment of liver cancer in the near future.

Anti-Stokes regime of laser cooling of solids

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

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.

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