Ionizing Radiation Effects in Single-Crystal and Polycrystalline YAG

The effect of ionizing-radiation fields on optical materials is predominantly seen in changes in the transmission properties of the materials. Both transient and permanent photodarkening can occur in passive and active optical elements as a result of exposure to either short-pulsed or steady-state radiation. In laser materials, such as YAG, such induced optical loss can result in significant degradation of the lasing characteristic of the material, making its selection for optical device applications in radiation environments unfeasible. In the present study, the effects of ionizing radiation on the optical response of undoped and 1.1%Nd-doped single-crystal and polycrystalline YAG have been investigated. Both room temperature and elevated temperature studies have been performed. An evaluation of the data shows some potential advantages of single-crystal over polycrystalline YAG in applications involving radiation exposure of the materials.