Local laser cooling of Yb:YLF to 110 K

Abstract

Minimum achievable temperature of ~110 K is measured in a 5% doped Yb:YLF crystal at λ = 1020 nm, corresponding to E4-E5 resonance of Stark manifold. This measurement is in excellent agreement with the laser cooling model and was made possible by employing a novel and sensitive implementation of differential luminescence thermometry using balanced photo-detectors.

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 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. The cooling efficiency for each photon absorbed is given by the ratio of the cooling power (P cool ) to the absorbed power (P abs ) [5]: …”

“…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].…”

Exciton-Polariton Gas as a Nonequilibrium Coolant

“…The best results so far have been obtained in ytterbium-doped crystals. Indeed, in spite of the long radiative lifetime and weak oscillator strength of the embedded ytterbium atoms, their high quantum efficiency allowed cooling from room temperature down to T ¼ 110 K [7,8]. In semiconductor materials, the excitonic transition has a much larger oscillator strength, a stronger coupling to phonons, and a shorter radiative rate.…”