Laser cooling of a solid is achieved when a coherent laser illuminates the material in the red tail of its absorption spectrum, and the heat is carried out by anti-Stokes fluorescence of the blue-shifted photons. Solid-state laser cooling has been successfully demonstrated in several materials, including rare-earth-doped crystals and glasses. Silica glass, being the most widely used optical material, has so far evaded all laser cooling attempts. Here we show the net cooling of high-purity Yb-doped silica glass samples that are fabricated with low impurities to reduce their parasitic background loss for fiber laser applications. The non-radiative decay rate of the excited state in Yb ions is very small in these glasses due to the low level of impurities, resulting in near-unity quantum efficiency. We report the measurement of the cooling efficiency as a function of the laser wavelength, from which the quantum efficiency of the Yb-doped silica is calculated.

当相干激光照射其吸收光谱的红色尾部中的材料时，就可以实现对固体的激光冷却，并且热量通过蓝移光子的反斯托克斯荧光来进行加热。固态激光冷却已成功在多种材料中得到证明，包括掺稀土的晶体和玻璃。迄今为止，石英玻璃是使用最广泛的光学材料，它避免了所有的激光冷却尝试。在这里，我们展示了高纯度掺Yb石英玻璃样品的净冷却过程，这些样品用低杂质制成，以减少光纤激光器应用中的寄生本底损耗。在这些玻璃中，由于杂质含量低，在Yb离子中激发态的非辐射衰减率非常小，导致量子效率接近统一。