Recent developments in cooling thulium-doped heavy-metal fluoride glass are presented. Thulium-doped fluorozirconate (ZBLANP) is cooled to 19 K below ambient with a multiple-pass pump scheme. This represents over an order of magnitude increase from the previously reported single-pass geometry. The results agree with a simple model for anti-Stokes fluorescence cooling that includes considerations of quantum efficiency and parasitic heating mechanisms. Issues relating to a practical optical refrigerator are examined, including a general model for the effects of multiple pump passes.
© 2003 Optical Society of America
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.6810) Instrumentation, measurement, and metrology : Thermal effects
(140.3320) Lasers and laser optics : Laser cooling
(160.5690) Materials : Rare-earth-doped materials
(300.2530) Spectroscopy : Fluorescence, laser-induced
C. W. Hoyt, M. P. Hasselbeck, M. Sheik-Bahae, R. I. Epstein, S. Greenfield, J. Thiede, J. Distel, and J. Valencia, "Advances in laser cooling of thulium-doped glass," J. Opt. Soc. Am. B 20, 1066-1074 (2003)