Abstract
Dependencies of optical transmittance and luminescence of crystals upon intensity of excitation at 1064 nm are investigated, when absorption of tetrahedrally coordinated ions centers) is saturated. The spectroscopic model of center in YAG crystals is proposed. Absorption saturation of crystals at 1064 nm have to be described by two absorption cross sections and arising from the local symmetry of centers. The cross sections slightly vary within the pointed range in dependency of level of the Cr dopant and a type of the dopant or The absorption band centered at 1000 nm is basically due to transition. Energy positions of and states are very close to each other, and the absorption band due to transition is masked by the absorption due to transition. The proposed model allows us to explain the dependence of the extent of luminescence polarization on the intensity of light exciting the crystal. Absorption from the metastable excited state is negligible; its absorption cross section is less than Linear losses from other centers are found in the crystals with a high level of the chromium dopant and with the calcium dopant.
- Received 1 June 1999
DOI:https://doi.org/10.1103/PhysRevB.61.988
©2000 American Physical Society