Laser Cooling in Fluoride Single Crystals

Abstract

In the last decade, laser cooling of solids has evolved from an exotic scientific curiosity into a promising and challenging technology, thanks to the improvements in the crystal growth technologies and to innovative pumping schemes. We report the recent progress in the field obtained with fluoride single crystals doped with Tm and Yb. High optical quality fluoride single crystals allowed us to reach cooling efficiency as high as 3%. By using a resonant pumping cavity, a temperature drop of ∼ 70 K was observed. The room for improvements lets us think that temperature drops even larger than 100 K can be achieved.

Laser cooling with PbSe colloidal quantum dots

“…The figure of merit for the cooling process, which has been discussed in Ref. 31, can be defined as F i cool σ i absλ p η i cool or F i cool λ p ∕λ i F − 1σ i abs λ p . It is easy to calculate that the figure of merit for the subsystem of QDs with diameter D 1 QD ≈ 5 nm is equal to F 1 cool ≈ 0, which means that really these QDs do not participate in the cooling process.…”