Optical retification of laser pulses in LiNbO3 by tilted-pulse-front pumping(TPFP) is a powerful way to generate terahertz(THz) pulses. Detailed theoretical analysis of the TPFP THz pulses generation efficiency and polarization with different pump beam polarization was presented. The THz generation efficiency for various of pump beam polarization angle and THz pulse polarization were also researched. The results predict that the magnitude of the THz electric field is maximized when the pump beam electric field vector is parallel to the LiNbO3 crystal axis.
Recently, Silicon nanowires(Si NWs) have been suggested as a promising candidate for solar energy harvesting. The Si NWs have the advantage of enhancing the optical absorption for broadband spectra, which increases the optical absorption significantly. It is of crucial importance for high efficiency solar cell. We applied the transient optical-pump THz emission spectroscopy to research Si NWs fabricated by chemical etching and to analyse the THz radiation mechanism. The experiment datas indicated that Si NWs enhance the optical absorption significantly. And the lifetime and dynamics properties of photoexcited carriers are important to the photovoltaic conversion efficiency of solar cell. Here the optical-pump terahertz-probe system was employed to study the ultrafast dynamics and transport properties of photoexcited carriers in Si NWs. The experiment results shown that carrier lifetime in Si NWs is approximate 0.7ns, and it reduces optical energy-conversion efficiencies of solar cell. However, compared to other silicon nanostructures, Si NWs fabricated by chemical etching have relative high values for both the carrier lifetime and mobility. The detailed analysis of the optical absorption and carriers dynamics would be significant for optimizing configuration of the silicon nanostructures.