Nonlinear optical phenomena in the Al_2O_3-P_2O_5, Er- and Yb-doped silica glasses

摘要

UV-photoinduced optical second harmonic generation (PISHG) in Al_2O_3-P_2O_5-SiO_2 glasses doped by Er and Yb rare earth ions has been investigated. The maximum output PISHG signal is observed at the delay time between the photoinducing nitrogen laser (λ = 337 nm) and probing laser (YAG: Nd; λ = 1060 nm) beams at about 7 ps, at temperatures of about 4.2 K and photoinducing beam powers lying within the range 0.45-0.82 GW cm~(-2). The essential effect of external electrostatic field and hydrostatic pressure on the output PISHG signal has been revealed. The Yb ions suppress the output PISHG. All the data are explained in terms of the ab initio molecular dynamics simulations and take into account anharmonic electron-vibration interactions. The problem of phase matching conditions is discussed.