Laser induced infrared spectral shift of the MgB2:Cr superconductor films.

During illumination of the MgB2:Cr2O3 films it was established substantial spectral shift of the infrared spectra in the vicinity of 20-50cm(-1). The excitations were performed by nanosecond Er:glass laser operating at 1.54µm and by microsecond 10.6µm CO2 laser. The spectral shifts of the IR maxima were in opposite spectral directions for the two types of lasers. This one observed difference correlates well with spectral shift of their critical temperatures. The possible explanation is given by performance of DFT calculations of the charge density redistribution and the time kinetics of the photovoltaic response. To understand the kinetics of the photoinduced processes the time kinetics of photoresponse was done for the particular laser wavelengths.

IR laser induced spectral kinetics of AgGaGe3Se8:Cu chalcogenide crystals.

The possibility to operate by optical spectra near the absorption edge gap was discovered for the AgGaGe3Se8:Cu semiconducting chalcogenide crystals under influence of microsecond CO2 laser with pulse energy 60 mJ operating at wavelength 10.6 µm. An occurrence of substantial photoinduced optical density was observed at wavelengths in the spectral range of 610-620 nm. Introducing of Cu ions leads to substantial spectral asymmetry in the observed spectra. The process achieves its maximum value after the 80-120 s of CO2 laser treatment and relaxes with almost irreversible changes after the same time. The contribution of thermo heating did not exceed 5-6%. Only the irreversible changes of the sample's surface topography were observed during the CO2 laser treatment, which do not influence the treatment. So the surface states do not play a principal role and the effect is prevailingly originated from the. The observed effect may be used for control of the CO2 laser power density.

Photoinduced spectra for magneto electric (1-x)BiFeO3-xCuFe2O4 nanocomposites.

In this work, we demonstrate possibility to use spectra of the parametrically tuned laser beam for operation by magnetoelectric properties of the (1-x)BiFeO(3-)(x)CuFe(2)O(4) (BFCI). The role of the photoexcited wavelength is crucial due to photoexcited phonons. It may indicate on a spectral sensitivity of the studied nanocomposites. We have studied spectral dependences of magneto-electric constant versus the magnetic field frequency for different sizes of the nanoparticles with and without the nanosecond laser pulses illumination and we have shown an occurrence of principal spectral shifts in the corresponding magneto-electric maxima. Additionally we have explored relative changes of dielectric permittivity and coercivity versus different photoinducing wavelengths. The performed experiments unambiguously show that the external laser treatment will lead to substantial shift of corresponding dielectric and magnetic parameters in the studied nanocomposites. It is principally the finding of clear spectral dependences for the mentioned dielectric and magnetic parameters. One can see their sensitivity to the photoinduced wavelength which reflects the photoexcitations of different part of wavelengths. One can see the spectral shift up to 100 nm for the two principal spectral maxima with respect to the dielectric and magnetic changes which may indicate on the two principally different contributions to the effects observed.