Optical refrigeration to 119 K, below National Institute of Standards and Technology cryogenic temperature

Melgaard, Seth D.; Seletskiy, Denis V.; Lieto, A. Di; Tonelli, M.; Sheik‐Bahae, Mansoor

doi:10.1364/ol.38.001588

Cited by 94 publications

(53 citation statements)

References 16 publications

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“…The YLF:Yb crystal was placed in a Herriott cell, 56 which was formed by a highly reective at input coupler mirror and a curved (R ¼ 25 cm) back reector separated by 35 mm. 9,53 The pump laser beam entered the non-resonant cavity though a 1-mm diameter hole in the input coupler and performed 5 round-trip passes through the crystal before unabsorbed pump light exited the input aperture to be dumped externally. A linearly-polarized single-mode ytterbium ber laser (IPG Photonics) operating at 1020 nm with a maximum power of 50 W (continuous wave) was used to excite the E4 / E5 transition of Yb 3+ in YLF (see Fig.…”

Section: Cryogenic Laser-cooling Of Yb 3+ -Doped Ylif 4 Crystalsmentioning

confidence: 99%

“…From experiments on the warming dynamics of the optical refrigerator, 58 a radiative heat load at the lowest temperatures of $2.4 Â 10 À4 W K À1 ($1.4 Â 10 À3 W K À1 without the MaxorbÔ coated clamshell) was estimated, 57 highlighting the dominance of radiative contribution to the heat load. A further reduction of P rad could be achieved by reducing the clamshell temperature T c , 53 for example with an external cooling stage such as a vibration-free TEC. The coefficient of performance (COP) for a solid-state optical refrigerator is given by the ratio of cooling power and supplied wall-plug power, i.e.…”

Section: Cryogenic Laser-cooling Of Yb 3+ -Doped Ylif 4 Crystalsmentioning

confidence: 99%

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Materials for Optical Cryocoolers

et al. 2013

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Vibration-free cooling of detectors to cryogenic temperatures is critical for many terrestrial, airborne, and space-based instruments. Cooling of solids by anti-Stokes fluorescence is an emerging refrigeration technology that is inherently vibration-free and compact, and enables cooling of small loads to cryogenic temperatures. In this Highlight, advances in laser-cooling of solids are discussed with a particular focus on the recent breakthrough laser cooling of Yb 3+ -doped YLiF 4 crystals to 114 K. The importance of the material structure, composition, and purity of laser-cooling materials and their influence on the optical refrigerator device performance is emphasized.

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Section: Cryogenic Laser-cooling Of Yb 3+ -Doped Ylif 4 Crystalsmentioning

confidence: 99%

Section: Cryogenic Laser-cooling Of Yb 3+ -Doped Ylif 4 Crystalsmentioning

confidence: 99%

Materials for Optical Cryocoolers

et al. 2013

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“…OR of rare earth doped insulator crystals, specifically ytterbium doped yttrium lithium fluoride (Yb:YLF), have shown the most promise for generating necessary cooling for infrared detectors, cooling below the NIST cryogenic standard of 123 K [1]. Insulator crystal OR utilizes an anti-Stokes phenomena [2] to generate cooling, using a photon to extract the crystal phonon energy and convert it to a higher energy photon.…”

Section: Introductionmentioning

confidence: 99%

Modelling thermal parasitic load lines for an optical refrigerator

Martin

Shomacker

Fraser

et al. 2015

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Optical refrigeration is currently the only completely solid state cooling method capable of reaching cryogenic temperatures from room temperature. Optical cooling utilizing Yb:YLF as the refrigerant crystal has resulted in temperatures lower than 123K measured via a fluorescence thermometry technique. However, to be useful as a refrigerator this cooling crystal must be attached to a sensor or other payload. The phenomenology behind laser cooling, known as anti-Stokes fluorescence, has a relatively low efficiency which makes the system level optimization and limitation of parasitic losses imperative. We propose and model a variety of potential designs for a final optical refrigerator, enclosure and thermal link; calculate conductive and radiative losses, and estimate direct fluorescence reabsorption. We generate parasitic load-lines; these curves define temperature-dependent minimum heat lift thresholds that must be achieved to generate cooling for detectors.

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“…Since, this technology has evolved at an accelerating pace as better materials become available. Lasers with nearzero heat generation have been proposed [6][7][8] , and demonstrated 9,10 , bulk cooling demonstrated down to 119 K in a Yb:YLF crystal 11 , new materials for laser refrigeration, such as quantum dots 12 and nanoparticles 13 have been suggested, and cooling of semiconductor nanobelts 14 demonstrated. These new approaches can allow the use of highphonon energy hosts for solid-state optical cooling.…”

Section: Introductionmentioning

confidence: 99%

Direct measurement of laser cooling of Yb:YAG crystal at atmospheric pressure using a fiber Bragg grating

et al. 2014

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Although Yb:YAG has been cooled in a vacuum environment 1 , we report for the first time an experimental demonstration of optical cooling at atmospheric pressure. A Yb:YAG crystal is supported on thin silica fibers, inside a matt-black chamber with air at atmospheric pressure, and pumped at 1029 nm in the pulsed and CW regimes. Direct measurement of the crystal surface temperature during pumping was made possible by using a low thermal-mass, transparent fiber Bragg grating (FBG) sensor. The FBG interrogation system has sufficient sensitivity to measure the background absorption of the sample to below 10 -4 cm -1 , and bulk cooling at a pump power as low as 17 mW. The dynamical measurement of the temperature allows the determination of the overall heat transfer coefficient of the sample in the air, of 22 W.m -2 K -1 . A temperature drop of 8.8 K from the chamber temperature is observed in the Yb:YAG crystal in air when pumped with 4.2 W at 1029 nm, close to 8.9 K observed in vacuum 1 . A background absorption α b = 2.9×10 -4 cm -1 is estimated with a pump wavelength at 1550 nm. Simulations predict further cooling when the sample's cross sectional area and the pump power are optimized, including absorption saturation effects. The choice of an efficient geometry, the use of a readily available temperature sensor in less controlled environments should simplify implementation of laser cooling systems and the development of commercial devices.

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Optical refrigeration to 119 K, below National Institute of Standards and Technology cryogenic temperature

Cited by 94 publications

References 16 publications

Materials for Optical Cryocoolers

Materials for Optical Cryocoolers

Modelling thermal parasitic load lines for an optical refrigerator

Direct measurement of laser cooling of Yb:YAG crystal at atmospheric pressure using a fiber Bragg grating

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