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We report on the generation of broadband terahertz (THz) pulses using Cherenkov-type generation in magnesium oxide-doped lithium niobate (MgO:LN). The efficiency of the output coupling process of THz radiation at higher frequencies into free space is considerably increased by the use of a properly cut silicon prism. The achieved spectrum is broader compared to the normal Cherenkov-cut geometry. Due to a considerably reduced propagation length in the absorbing MgO:LN, the effective application of longer crystals is possible. Thus, the measured spectral in tensity is much higher and the spectrum broader

We demonstrate a terahertz (THz) beam steering method using difference frequency generation that is based on the principle of phased array antennas. A strip-line photoconductive antenna was illuminated by two spatially dispersed beams produced from an ultrafast laser. THz radiation with a bandwidth of 65 GHz was generated from the overlapping area of the two beams, between which the frequency difference was approximately constant. We confirmed that the THz beam can be steered by tilting one of the incident pump beams so as to change their relative phase relation. The steering range of the THz beam was 29 degrees when the angle between the incident pump beams was only varied within a range of 0.155 degrees, that is, 187 times less. In addition, by laterally shifting one of the pump beams, the frequency of the THz radiation could be tuned from 0.3 to 1.7 THz. This technique can be applied to high-speed terahertz imaging and spectroscopy systems.

A model for debris clouds produced by impact of hypervelocity projectiles on multiplate structures Appl. Phys. Lett. 93, 211905 (2008); 10.1063/1.3029747 Study on microwave emission mechanisms on the basis of hypervelocity impact experiments on various target platesA shock physics based model of the oblique impact of a thin plate by a spherical projectile AIP Conf.