The requirements tor obtaining cryogenic temperatures (i.e. 150 K and below) by anti-Stokes fluorescence cooling are analysed for a dielectric cooling medium located inside the cavity of a diode-pumped solid slate laser. The cooling efficiency is derived in terms of pump beam parameters, intracavily loss associated with the cooling medium, reabsorption and saturation effects in the gain medium, radiative and conductive heat load on the cooling medium, and finally bulk and surface heating effects. Using experimental data for a Yb 3+:ZrF4-BaF2-LaF3-AlF 3-NaF [ZBLAN] cooling medium and a Yb3+:KY(WO4) 2 [KYW] gain medium, the conditions for optimum cooling efficiency are obtained. Based on realistic materials properties, the analysis shows that it is feasible to obtain a cooling efficiency (i.e. cooling power per input diode pump power) of approximately 0.1% at an operating temperature of 150K, with a heat lift up to 30 mW.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics