The role of absorption saturation in optical refrigeration (Conference Presentation)

The role of pump saturation in high-power optical refrigeration is investigated. Employing both Z-scan and intensity-dependent PL techniques, we measure the pump saturation intensity in Yb:YLF versus the temperature. We find that the absorption efficiency, and consequently the cooling efficiency can be limited at cryogenic temperatures under power scaling (when substantial heat lift is desired) unless multi-pass pumping schemes are tailored to control the average pump intensity inside the crystal.