On the microscopic level, the polarization-sensitive photocurrent is a manifestation of the sensitivity of the elementary processes of the elastic and non-elastic electron-photon scattering to the photon momentum and to the crystal symmetry. The studying of the polarization-sensitive photocurrents is of interest for photonics and optoelectronics, in particular, for THz generation and the development of advanced optoelectronic devices. This phenomenon can be described in terms of the second-order susceptibility of the medium that can be revealed from the measured photocurrent. Irradiation of the metallic and semiconductor materials with laser pulses can lead to the generation of a photocurrent, which depends on the polarization and incidence angle of the laser beam. The pronounced dependence of the photocurrent on the angle of incidence and polarization of the excitation beam opens avenues toward the development of polarization- and position-sensitive detectors for industrial and space applications. Obtained experimental results are in agreement with the developed phenomenological theory, which describes transverse and longitudinal photocurrents due to SPGE and PDE in terms of relevant second-order nonlinear susceptibilities and allows us to obtain their dependences on the angle of incidence and polarization of the excitation laser beam. Specifically, the irradiation of the film with the s-polarized excitation beam produces a monopolar photoresponse, while at p-polarized excitation, the photoresponse is bipolar, having a short front and long tail. However, the temporal profile of the transverse photocurrent pulse is monopolar at any polarization and angle of incidence, while the temporal profile of the longitudinal photocurrent pulse depends on the polarization of the excitation beam. It is shown that in both the transverse and the longitudinal configuration, the surface photogalvanic (SPGE) and photon drag effects (PDE) contribute to the observed photocurrent. We performed the investigation of the polarization-sensitive photocurrent generated in silver-palladium metal-semiconductor nanocomposite films under irradiation with nanosecond laser pulses at the wavelength of 2600 nm.

Lecroy wavesurfer 42xs