| Popis: |
Picosecond blue-light induced infrared absorption (BLIIRA) was investigated in periodically poled KTiOPO4, Rb:KTiOPO4, RbTiOPO4, KTiOAsO4 and RbTiOAsO4. The dependence of BLIIRA on blue light average power and intensity as well as on crystal temperature was studied. The results show the presence of at least two different types of color centers. A higher level of remnant absorption was observed in the phosphates compared to the arsenates. We attribute the largest portion of the induced absorption to photo-generated electrons and holes self-trapped in the proximity to Ti4+ and O2- ions, respectively, forming polaron color centers. Stabilization of these centers is aided by the presence of mobile alkali metal vacancies in the crystal. The lower level of remnant absorption in arsenates is related to higher population of thermal phonons related to TiO6 group vibrations in arsenates. |
