Precise determination of minimum achievable temperature for solid-state optical refrigeration

Abstract

We measure the minimum achievable temperature (MAT) as a function of excitation wavelength in anti-Stokes fluorescence cooling of high purity Yb3+-doped LiYF4 (Yb:YLF) crystal. Such measurements were obtained by developing a sensitive noncontact thermometry that is based on a two-band differential luminescence spectroscopy using balanced photo-detectors. These measurements are in excellent agreement with the prediction of the laser cooling model and identify MAT of 110 K at 1020 nm, corresponding to E4–E5 Stark manifold transition in Yb:YLF crystal

Development of ytterbium-doped oxyfluoride glasses for laser cooling applications

“…Since 1995 laser cooling based on anti-Stokes fluorescence have been reported in a wide variety of low phonon energy host materials9101112 doped with Yb 3+ , Er 3+ and Tm 3+ ions12131415. Studies have been focused on the Yb 3+ (4f 13 ) ion as it has a very simple energy level structure consisting of only two manifolds, the ground ( 2 F 7/2 ) and excited ( 2 F 5/2 ) states which are well separated by about 10,000 cm −1 .…”

Comparative spectroscopic studies of Ho: KPb2Cl5, Ho: KPb2Br2, and Ho: YAG for 2 μm laser cooling applications

“…There is a continued interest in the development of rare earth doped materials for applications in optical refrigeration (laser cooling) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Laser refrigeration of solids has received significant attention for the development of practical allsolid-state cryo-coolers for various applications such as biomedical sensing, cooling sensors, and space-borne radiation detectors [1][2][3][4][5][6][7].…”

“…Laser refrigeration of solids has received significant attention for the development of practical allsolid-state cryo-coolers for various applications such as biomedical sensing, cooling sensors, and space-borne radiation detectors [1][2][3][4][5][6][7]. Laser cooling of solids by anti-Stokes fluorescence occurs when the average energy of the photons emitted is greater than those absorbed, removing the difference in energy and resulting in a cooling effect.…”

“…Laser cooling research has been mainly focused on rare-earth doped crystals and glasses as well as semiconductors [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Optical cooling of rare-earth doped solids has been demonstrated from Yb 3+ , Tm 3+ , and Er 3+ doped materials [5][6][7][8][9][10][11][12][13] [8][9][10][11][12].…”

“…Optical cooling of rare-earth doped solids has been demonstrated from Yb 3+ , Tm 3+ , and Er 3+ doped materials [5][6][7][8][9][10][11][12][13] [8][9][10][11][12]. Potential rare earth candidates for long wavelength IR fluorescence include Ho 3+ , Dy 3+ , and Nd 3+ with transitions at ~2 μm, ~3 μm, and ~5 μm.…”