Research on the Optical Refrigeration Performance of Ho3+:YLF at Ultra-Low Temperatures

Evan P. Chicklis, Charles S. Naiman, R. C. Folweiler +1 more

朵 聂

A. Rayner, N. R. Heckenberg, Halina H. Rubinsztein-Dunlop

Seth D. Melgaard, Denis V. Seletskiy, Alberto Di Lieto +2 more

A record low temperature in optical refrigeration is demonstrated by cooling Yb:YLF crystal to 128K ± 5K (∼−150 C) at λ=1020 nm corresponding to its E4-E5 Stark manifold resonance. The estimated cooling power is 165 mW.

Guang-Zong Dong, Xinlu Zhang

We report a theoretical scheme for realizing efficient and enhanced laser cooling in Ho3+-doped solids, based on ground-state absorption (GSA) of I58→I57 at around 2.07 μm and excited-state absorption (ESA) of I55→F55 at around 2.28 μm. The upconversion-quenching-induced heat that usually is found in Ho3+ optical refrigeration can be significantly alleviated by using the copumping scheme, so the cooling power density and the cooling efficiency are greatly improved. The scheme works at temperatures above 133 K, and can shorten the time needed to reach the minimum attainable temperature of the cooling system. Besides, the dopant concentration is allowed to be promoted to around 1%. The copumping scheme can also be applied to other multilevel (such as Tm3+ and Er3+) optical refrigeration systems to improve the cooling performance.

Stefan Püschel, Christian Kränkel, Hiroki Tanaka

We present temperature-dependent spectroscopy of cubic Yb:KY3F10 and report on its first laser cooling. In comparison with Yb:YLF, Yb:KY3F10 has an intrinsically higher cooling potential at low temperatures so suited for optical refrigerators.