Novel approach for solid state cryocoolers

Volpi, Azzurra; Lieto, A. Di; Tonelli, M.

doi:10.1364/oe.23.008216

Cited by 21 publications

(16 citation statements)

References 21 publications

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“…The fitted values of EQE and background absorption allow a comparison with the cooling performances of YLF 4,16 . Comparing these data, it can be noticed that LLF shows depressed cooling performances if compared to YLF doped at the same doping level.…”

Section: Laser Cooling Measurementsmentioning

confidence: 99%

Investigation of Yb-doped LiLuF₄single crystals for optical cooling

et al. 2016

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Optical cooling of solids, relying on annihilation of lattice phonons via anti-Stokes fluorescence, is an emerging technology that is rapidly advancing. The development of high-quality Yb-doped fluoride single crystals definitely led to cryogenic and sub-100-K operations, and the potential for further improvements has not been exhausted by far. Among fluorides, so far the best results have been achieved with Yb-doped LiYF 4 (YLF) single crystals, with a record cooling to 91 K of a stand-alone YLF:10%Yb. We report on preliminary investigation of optical cooling of an LiLuF 4 (LLF) single crystal, an isomorph of YLF where yttrium is replaced by lutetium. Different samples of 5% Yb-doped LLF single crystals have been grown and optically characterized. Optical cooling was observed by exciting the Yb transition in single-pass at 1025 nm and the cooling efficiency curve has been measured detecting the heating/cooling temperature change as a function of pumping laser frequency.

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Section: Laser Cooling Measurementsmentioning

confidence: 99%

Investigation of Yb-doped LiLuF₄single crystals for optical cooling

et al. 2016

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“…Recently, the net cooling of a Yb 3+ /Tm 3+ co‐doped solid was experimentally achieved and the cooling efficiency was reported to be higher than of the single RE‐doped solid under the same synthetic conditions. [ 62,82 ] The cooling scheme is slightly different from the Ho 3+ /Tm 3+ pair proposed by Dong as the energy of the acceptor state (Tm 1 G 4 ) is about twice the energy of the donor excited state (Yb 3+ 2 F 5/2 ) while nonradiative relaxation of the excited multiplet manifold ( 1 G 4 ) is prevented by the absence of close enough underlying states. A pair of Yb ions provide the energy to excite the 1 G 4 multiplet just above the first Stark level.…”

Section: Rare‐earth Doped Solidsmentioning

confidence: 99%

“…Net laser cooling has been achieved in YLF host crystals doped with Yb, [ 6 ] Tm, [ 60 ] Ho, [ 61 ] and Yb/Tm co‐doping. [ 62 ]…”

Section: Rare‐earth Doped Solidsmentioning

confidence: 99%

Quantum Point Defects for Solid‐State Laser Refrigeration

et al. 2020

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Herein, the role that point defects have played over the last two decades in realizing solid‐state laser refrigeration is discussed. A brief introduction to the field of solid‐state laser refrigeration is given with an emphasis on the fundamental physical phenomena and quantized electronic transitions that have made solid‐state laser‐cooling possible. Lanthanide‐based point defects, such as trivalent ytterbium ions (Yb3+), have played a central role in the first demonstrations and subsequent development of advanced materials for solid‐state laser refrigeration. Significant discussion is devoted to the quantum mechanical description of optical transitions in lanthanide ions, and their influence on laser cooling. Transition‐metal point defects have been shown to generate substantial background absorption in ceramic materials, decreasing the overall efficiency of a particular laser refrigeration material. Other potential color centers based on fluoride vacancies with multiple potential charge states are also considered. In conclusion, novel materials for solid‐state laser refrigeration, including color centers in diamond that have recently been proposed to realize the solid‐state laser refrigeration of semiconducting materials, are discussed.

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“…We have recently investigated different spectral methods for temperature estimation of cryogenic Yb:YLF samples and demonstrated a temperature estimation accuracy below ± 1 K in the 78-300 K region [23], and used this for analyzing laser performance [24,25]. Similar methods had already been in use for temperature estimation of Yb:YLF and Yb:YAG by the cryogenic optical refrigeration community [26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Error analysis of contactless optical temperature probing methods for cryogenic Yb:YAG

et al. 2021

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In this work, we have investigated six different in situ optical contactless temperature probing methods for cryogenic Yb:YAG systems. All the methods are based on variation of fluorescence spectra with temperature, and they either look at the width of the emission line, the ratio of the emission intensity at different wavelengths and to the overall spectral change at selected wavelength intervals. We have shown that, for Yb:YAG crystal with homogeneous temperature distribution, one can perform real-time contactless optical temperature measurements with a ± 1 K accuracy in the 78–300 K range. We have further tested the methods in measuring the average temperature of Yb:YAG rods at up to 500 W absorbed pump power level. We have seen that, a real-time temperature measurement accuracy of ± 5 K is feasible in both lasing and non-lasing situations for estimating the average temperature of crystals under nonhomogeneous thermal load. The techniques are quite valuable in evaluating the bonding quality of Yb:YAG crystals in cryogenic systems. Moreover, the real-time temperature information provides feedback on parameters like cavity alignment status and extraction efficiency to the laser engineers while optimizing the system.

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Novel approach for solid state cryocoolers

Cited by 21 publications

References 21 publications

Investigation of Yb-doped LiLuF₄single crystals for optical cooling

Investigation of Yb-doped LiLuF₄single crystals for optical cooling

Quantum Point Defects for Solid‐State Laser Refrigeration

Error analysis of contactless optical temperature probing methods for cryogenic Yb:YAG

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Novel approach for solid state cryocoolers

Cited by 21 publications

References 21 publications

Investigation of Yb-doped LiLuF4single crystals for optical cooling

Investigation of Yb-doped LiLuF4single crystals for optical cooling

Quantum Point Defects for Solid‐State Laser Refrigeration

Error analysis of contactless optical temperature probing methods for cryogenic Yb:YAG

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Investigation of Yb-doped LiLuF₄single crystals for optical cooling

Investigation of Yb-doped LiLuF₄single crystals for optical cooling