title: Optical refrigeration to 119 K, below National Institute of Standards and Technology cryogenic temperature.
abstract: We report on bulk optical refrigeration of Yb:YLF crystal to a temperature of ~124 K, starting from the ambient. This is achieved by pumping the E4-E5 Stark multiplet transition at ~1020 nm. A lower temperature of 119±1 K (~-154C) with available cooling power of 18 mW is attained when the temperature of the surrounding crystal is reduced to 210 K. This result is within only a few degrees of the minimum achievable temperature of our crystal and signifies the bulk solid-state laser cooling below the National Institute of Standards and Technology (NIST)-defined cryogenic temperature of 123 K.
authors: University of New Mexico, Physics and Astronomy Department, Albuquerque, New Mexico 87131, USA. melgaard@unm.edu
authors: Seth D
authors: SD
authors: Melgaard
authors: Denis V
authors: DV
authors: Seletskiy
authors: Alberto
authors: A
authors: Di Lieto
authors: Mauro
authors: M
authors: Tonelli
authors: Mansoor
authors: M
authors: Sheik-Bahae