A time-resolved reflection pump-probe method was combined with a surface plasmon resonance technique in Kretschmann geometry for the investigation of ultrafast light-induced processes in thin films. Transient changes in the gold layer's reflectivity were observed when the layer was excited by 3 ps duration pulses with photon energy exceeding the interband transition and by probing with photon energy close to the interband transition. Comparison of the experimental and modeling results has shown that the imaginary part of the dielectric function of gold increases linearly during excitation, whereas the real part remains unchanged. The decay of the light-induced changes has two components. The first component is faster than the pulse duration, and the second is much longer than 1.5 ns; they are related to cooling of the electron plasma and lattice, respectively.

The photovoltaic effect in a GaAs p-n junction exposed to short laser pulses of the 1.06–3.0 μm spectral range is investigated experimentally. At a low excitation level of 1.06 μm radiation, the intraband single photon absorption of light dominates, and the photoresponse is found to be caused mainly by the hot carriers. As the laser intensity is increased, the photoresponse signal across the junction consists of two components; the hot carrier photovoltage and the classical photovoltage due to electron-hole pair generation resulting from two-photon absorption. The generation-induced photovoltage decreases with the increase in the radiation wavelength following the reduction of the two-photon absorption coefficient, while the carriers are shown to be heated by the intraband light absorption as well as by residual photon energy left over during the electron-hole pair generation. It is established that carrier heating by light reduces conversion efficiency of a solar cell not only via the thermalization process but also due to the competition of the hot carrier and the classical photovoltages which are of opposite polarities.

The Kerr rotation and ellipticity of Bi1.8Y1.2Fe5O12 films (Bi:YIG) with the easy axis of magnetization perpendicular to the film plane was investigated in a Kretschmann setup at the wavelength 1.31 μm. The sample was coated by a thin Au film in order to excite plasmons at the free Au surface. An ellipsometric setup, supplemented with a magnetic field oriented perpendicularly to the film plane was used to measure the reflected p and s components of an incoming p polarized wave. The phase difference between the outgoing p and s waves was found by an indirect procedure. A minimum in Kerr rotation and a maximum in Kerr ellipticity could be observed at the surface plasmon resonance angle. Using the Berreman formalism, the experimental curves for the prism/Bi:YIG/Au system could be reproduced by bulk optical constants of the constituents. The asymmetry of the ellipticity curve is demonstrated to arise from a sudden variation in the phase. The effects of the field distribution and the surface roughness are discussed.

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We describe a mobile spectroscopic system for trace gas analysis based on the open path differential absorption spectrometer and the photoacoustic spectrometer. The first method allows long distance measurements (up to a few kilometers) while the second one provides local in situ detection of pollutants. The open path system is based on the nanosecond (f = 10 Hz, tau = 5 ns) lamp pumped Nd:YAG laser and a tunable two cascade optical parametric generator operating in the 5-12 microm spectral region. This source was mounted into the lidar setup based on the coaxial transmitter/receiver. The photoacoustic system was constructed using the same laser as well as a nonresonant photoacoustic cell.