Temperature dependences of the lasing parameters at zero-phonon lines of doped crystals

A theoretical analysis is made of some features of the threshold operating conditions of a laser utilizing zero-phonon lines of doped crystals. It is shown that the appearance of the long-range order under lasing conditions corresponding to a change in the radiation statistics depends critically not only on the pumping rate but also on the crystal temperature. The temperature dependences of the intensity and lasing line width are investigated. Estimates are obtained for color centers in leucosapphire.