摘要： Infrared lasers, especially those having a wavelength of either 10.6 μm or 1.06 μm are of great technological importance. Unfortunately, many dielectric materials, such as common ceramics absorb very poorly the latter wavelength since it falls within their large bandgap. However, some materials do not follow this general trend and strongly absorb moderate-energy-density (10–100 J/cm2) laser radiation of both types, although their bandgap extends into the infrared far beyond 1 μm and contains no intrinsic energy levels. The present study was motivated by the observation that IR-laser melting of some of these oddly behaving materials seems to be accompanied by appearance of strong visible absorption. The evolution of the optical properties and crystal structure of one of them, YSZ, as well as that of alumina, having a regular behavior, was studied by optical microscopy, SEM, XRD, Raman spectroscopy, optical spectroscopy and DRIFTS. As a result, it was shown for the first time that the melting of YSZ by 1.06 μm laser radiation is only possible due to F-centers forming in the tetragonal structure of the material, giving rise to a broad absorption continuum, which covers the entire bandgap of the material, including that wavelength, and when F-centers generation is inhibited, melting does not occur anymore. In order to explain that phenomenon, the possibility of multiple energy levels arising within the band gap because of F-center coupling and anisotropy was studied theoretically. Thus, a simple model was constructed, representing F-center clusters as coupled potential wells with variable separations between them and variable effective electron mass due to anisotropy. The model with just two wells produced multiple energy states distributed throughout the bandgap of the material, thus offering support for said hypothesis.