Local laser cooling of Yb:YLF to 110 K

Minimum achievable temperature of similar to 110 K is measured in a 5% doped Yb:YLF crystal at lambda = 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. (C) 2011 Optical Society of America