Alternative technique for laser cooling with superradiance

Nemova, Galina; Kashyap, Raman

doi:10.1103/physreva.83.013404

Cited by 16 publications

(9 citation statements)

References 18 publications

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“…Spontaneous Brillouin scattering has been utilized to cool targeted vibrational modes of a microresonator [79]. Coherent processes invoking stimulated Raman scattering [80,81] and superradiance [82,83] were also proposed for laser cooling applications. Athermal lasers and amplifiers have been proposed, where the active medium is co-doped with rare-earth ions [84][85][86][87].…”

Section: Introductionmentioning

confidence: 99%

Cryogenic optical refrigeration

et al. 2012

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Doc. ID 157833)We review the field of laser cooling of solids, focusing our attention on the recent advances in cryogenic cooling of an ytterbium-doped fluoride crystal (Yb 3+ :YLiF 4 ). Recently, bulk cooling in this material to 155 K has been observed upon excitation near the lowest-energy (E4-E5) crystal-field resonance of Yb 3+ . Furthermore, local cooling in the same material to a minimum achievable temperature of 110 K has been measured, in agreement with the predictions of the laser cooling model. This value is limited only by the current material purity. Advanced material synthesis approaches reviewed here would allow reaching temperatures approaching 80 K. Current results and projected improvements position optical refrigeration as the only viable all-solid-state cooling approach for cryogenic temperatures.

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Section: Introductionmentioning

confidence: 99%

Cryogenic optical refrigeration

et al. 2012

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“…We want to emphasize that in the case of cooling with superradiance (SR) in a rare-earth doped system, presented in Ref. 30, the radiative lifetime is even shorter than in the case of cooling with QDs doped in glass, but SR pulse generation is an extremely difficult process, which requires a number of conditions imposed on the geometry of the sample and characteristic times of the system to be met. In contrast, there are no limitations that need to be considered in the use of QDs for cooling other than those discussed in this paper.…”

Section: Resultsmentioning

confidence: 99%

Laser cooling with PbSe colloidal quantum dots

Nemova

Kashyap

2012

J. Opt. Soc. Am. B

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We present a theoretical scheme for laser cooling with colloidal lead-salt PbSe quantum dots (QDs) doped in a glass host. The laser cooling process is based on the anti-Stokes fluorescence in QDs. The relatively short (microsecond range) lifetime of the excited level of the PbSe QD allows the cooling process to be accelerated and new materials with higher phonon energy to be used as hosts, which are normally considered unsuitable for cooling with rare-earth ions. The considerable increase (by ∼10 4 ) in the absorption cross section of the PbSe QD in comparison with the absorption cross section of rare-earth ions doped in glasses or crystals increases the efficiency of the cooling process considerably, lowering the pump power requirements.

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“…These conditions were presented and discussed in Ref. 21 and are briefly described by the following inequalities:…”

Section: Laser Cooling With Super-radiancementioning

confidence: 99%

“…As a consequence, the radiation intensity is proportional to the square of the number of excited atoms, I ~ N 2 . 21 This "fast" relaxation rate is the crucial point of the new approach to the cooling process based on super-radiance. It permits a substantial increase in the rate of cooling in comparison with the traditional cooling cycle based on incoherent anti-Stokes spontaneous radiation, to reach cryogenic temperatures in a shorter time for any host.…”

Section: Laser Cooling With Super-radiancementioning

confidence: 99%

Recent advances in laser cooling of solids

Nemova

Kashyap

2013

Photonics North 2013

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The recent achievements devoted to cooling of solids with a laser are presented in this paper. We discuss the latest results of traditional laser cooling of solids based on rare earth ions and new techniques based on colloidal lead-salt quantum dots doped in a glass host, laser cooling in Tm 3+ -doped oxy-fluoride glass ceramic. Relatively short (microsecond) lifetime of the excited level of the PbSe QDs compared to the millisecond lifetime of the excited level of RE ions allows an acceleration of the cooling process and provides an opportunity to use new materials with higher phonon energy as hosts, which are normally considered unsuitable for cooling with RE ions. Another new approach to the laser cooling problem based on super-radiance has been considered in this paper. The advantages of optical refrigeration with rare earth doped semiconductors, in which not only optically active electrons of the 4f shell but the valence and conduction bands of the host material are involved in cooling cycle is discussed. It is shown that involving the valence and conduction bands of the host in the cooling cycle allows the pump wavelength to be shorter than mean fluorescence wavelength. Raman laser cooling of solids as well as observation of spontaneous Brillouin cooling have been presented.

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Alternative technique for laser cooling with superradiance

Cited by 16 publications

References 18 publications

Cryogenic optical refrigeration

Cryogenic optical refrigeration

Laser cooling with PbSe colloidal quantum dots

Recent advances in laser cooling of solids

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