Evaluation of Anti-Stokes Superradiance Cooling Thulium Doped Solids

A theoretical scheme for laser cooling thulium doped solids with optical superradiance is presented. The superradiance is coherent, sharply directed spontaneous emission of photons by an ensemble of excited ions in the solid-state host, the properties of which are much different from the conventional, incoherent anti-Stokes fluorescence radiating through all directions. In this paper, we consider a thulium doped ZBLAN sample pumped with continuous-wave laser at 1.9 μm and pulse laser at 1.8 μm. The induced anti-Stokes superrandiance at 1.8 μm removes the matrical phonons energy much effectively and quickly, because of the intensity of superradiance proportional to the square of the number of excited Tm ions. The numerical evaluations of the superradiance cooling performance, especially in the net cooling power and the cooling efficiency, is discussed.