Infrared-induced nonlinear optical effects in chalcogenide glasses

The second-order nonlinear optical effects such as second harmonic generati on (SHG) and linear electrooptics (LEO) in the middle infrared spectral ran ge (5-15 mum) are experimentally observed for the first time. We have found that the novel As2Te3-BaBr2-BiCl2 chalcogenide glasses, possessing transmi ssion windows within the 3-45 mum spectral range, have both photoinduced SH G equal to 0.0012 pm/V and comparable values of photoinduced electrooptics effect at wavelength of excitation (lambda =10.6 mum). The photoinduced anh armonic electron-phonon interaction play the major role in the observed phe nomena. A good correlation between the IR-induced nonlinear optical suscept ibilities and the photoinduced anharmonic electron-quasi-phonon interaction s is demonstrated. The pump-probe experiment shows that the intensity-depen dent maximum of the LEO is shifted towards the higher delaying times compar ing with the SHG ones. Comparison of theoretical simulations with experimen tal measurements indicate dominant role of the electron-phonon anharmonic s ubsystem in the observed effects. (C) 2001 American Institute of Physics.