Due to lattice disorder, glassy semiconductors have energy levels in their bandgaps (gap states) that can be populated by sub-gap illumination or due to recombination of photo-excited carriers. The non-linear optical (NLO) response induced by high-intensity femtosecond (fs) laser pulses develops together with the gap states excitation. These effects in non-crystalline semiconductors have not yet been well studied. In this work, we use two realizations of the pump-probe method [1,2] to study the NLO response of chalcogenide glassy semiconductors of the systems As40SxSe1-x and As40SexTe1-x with fs resolution in time upon illumination by fs laser pulses with the peak wavelengths λp of 0.79 and 1.57 μm.
© 2019 IEEEPDF Article