GaBiAs layers have been grown by molecular beam epitaxy at low (270–330°C) temperatures and were characterized by several experimental techniques. It was shown that the spectral photosensitivity cutoff wavelength reaches ∼1.4μm when the growth temperature is as low as 280°C. Optical pump–terahertz probe measurements made on these layers have evidenced that the electron trapping time decreases with decreasing growth temperature from 20 to about 1ps. GaBiAs layers were used for manufacturing photoconductive terahertz emitters and detectors, which, when excited with Ti:sapphire laser pulses, have demonstrated a signal bandwidth of 3THz.

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Large optical bleaching effect was found in epitaxial InN layers from Z-scan measurements at 1.054μm laser wavelength. Optical transmittance increases nearly five times at the largest light intensities used in experiment. The bleaching recovery time shorter than 3ps was evidenced from time-resolved measurements at this wavelength, which is much faster than the electron lifetimes of 40 and 240ps determined on two epitaxial layers by visible pump-terahertz probe technique. Spectral investigations of the bleaching effect performed in the wavelength range from 1to1.55μm support the conclusions on a narrow band gap of InN.

GaBiAs layers with Bi content reaching 8.4% are grown by MBE technique at low temperatures. All layers were of p-type with carrier densities ranging from 3 × 10 14 to 2 × 10 15 cm −3 and resistivities exceeding 60 cm. Energy bandgap of the gallium bismide alloys as determined from spectral measurements of the optical absorption, photoconductivity and photoluminescence decreases linearly with increasing Bi content. Optical pump-terahertz probe measurements made on these layers show that the carrier density dynamics is best described by a double-exponential decay. The shorter of the time constants corresponds to the electron trapping and the longer time constant corresponds to the trap emptying times. It has been found that the electron trapping cross-section is of the same order of magnitude as the corresponding parameter for As-antisite traps in LTG GaAs; therefore, it is reasonable to assume that As antisites play a significant role in carrier recombination processes in GaBiAs, too.

The linear and nonlinear optical response of colloidal PbSe nanocrystals was investigated. Optical nonlinearity and its recovery dynamics in this system was measured and compared with other available experimental data. The saturation irradiance value for the bleaching effect and absorption cross--section were determined.