Spectroscopic ellipsometry measurements were performed in the region 0.5-5.0 eV on single crystals of cuprates with incommensurate-type structure. Three components of the dielectric function were determined by making use of the measurements made on two developed planes of orthorhombic crystals. The main optical transitions contributing to the optical response of the crystals of various chemical compositions and structural parameters were revealed. The relationship between optical anisotropy and crystal structure was analysed.

A photomagnetoelectric effect has been investigated in semiconductors InAs and Cd x Hg 1−x Te (x = 0.2 and 0.26) excited by Q-switched neodymium-YAG laser. The photomagnetoelectric signal undergos double--sign-inversion when the intensity of the exciting light pulses exceeds a critical value Ic = 5 × 10 24 photons/(cm 2 s) for InAs and (1-4) × 10 24 photons/(cm 2 s) for Cd x Hg 1−x Te samples. It is shown that a frequency spectrum of photomagnetoelectric response is broadened significantly in the region of high frequencies. In general three frequency bands were distinguished. From this investigation it follows that using laser pulses of a duration topt ∼ 1−10 ps the photomagnetoelectric signal in the terahertz range may be generated.

Photocurrent and electroreflectance spectroscopies are combined to study the transformation of the quantum confined Stark effect under high electric fields in shallow InGaAs/GaAs quantum wells. Experimental evidences of exciton quenching and carrier tunneling out of the well are obtained. The coupling between quasibound and continuum states in the strong electric field region results in the increase of absorption below the band gap of the barrier. no HCCJIenOBaHHIO CIIeKTpOB @OTOOTKnUKa If 3JIeKTpOOTpaXeHHR H3yWHa TpaHC@OpMaUUX KBPHTO-

The excitation-energy dependences and relaxation times of photoinduced changes of excitonic lines in type-I GaAs/AlAs QW structures are studied by the photo-and wavelength-modulated reflectance spectroscopies. The optical data indicate that photoinduced broadening/quenching of excitonic lines dominates in the modulation spectra under photoexcitation within the QW by He-Ne laser. It was found that characteristic time ofthese photoinduced changes varies from milliseconds at 300 K to seconds at 120 K and reduces under illumination above the AlAs band gap. Moreover, different time constants and their temperature dependences were obtained for QW-and buffer layer-related optical features. It was suggested that photoinduced changes of excitonic spectra could be associated with the f-X electron transfer effects and creation of excess holes in the QW under He-Ne excitation.