We report on the observation of the helicity-dependent photoresponse of the 20-μm-thick silver–palladium (Ag/Pd) nanocomposite films. In the experiment, 120 fs pulses of Ti:S laser induced in the film an electric current perpendicular to the incidence plane. The photoinduced current is a linear function of the incident beam power, and its sign depends on the beam polarization and angle of incidence. In particular, the current is zero for the p- and s-polarized beams, while its sign is opposite for the right- and left-circularly polarized beams. By comparing experimental results with theoretical analysis, we show that the photoresponse of the Ag/Pd nanocomposite originates from the photon drag effect.

Highly nonlinear optical properties of nanocarbon materials make them perspective candidates for saturable absorption (SA) applications, characterized by a short-term decrease in the optical medium absorption at high incident light intensity. The nonlinear optical properties and SA of aqueous suspensions of 5 nm detonation nanodiamonds (DNDs) have been studied by the z-scan technique under irradiation with nanosecond laser pulses at wavelengths of 532 and 1064 nm. The saturation intensity and nonlinear absorption coefficient describing the SA were obtained for concentrations of DND suspensions ranging between 0.5 and 5 wt %. It was concluded that the single-digit DND suspensions are suitable for optical limiting only at relatively high intensities of incident radiation, with saturation intensities of ∼5.9 and 14.1 MW/cm2 for 532 and 1064 nm incident excitation, respectively.

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