Multiple phase gratings in pure, Yb- and P-doped Pb5Ge3O11 after differentthermal treatments

Multiple phase gratings are written in pure, Yb- and P-doped Pb5Ge3O11 crys tals: a fast grating and a slow grating with substantially different respon se times compensate each other. Doping and thermal treatments have strong i nfluences on the behavior of both gratings. Reduction treatments of Yb-dope d samples lead to a significant decrease of the response time of the slow g rating, while that of the fast grating is diminished by more than two order s of magnitude. P doping significantly increases the response time of the f ast grating. Possible origins of both gratings are discussed. (C) 1999 Amer ican Institute of Physics. [S0021-8979(99)09915-6].