Terahertz beam steering and frequency tuning by using difference frequency mixing

Terahertz (THz) beam steering by using difference frequency mixing and phased array antenna principle was demonstrated. The THz radiation was generated by pumping with spatially dispersed beams produced from an ultrafast laser. And the THz beam could be steered by tilting one of the incident pump beams so as to change their relative phase relation. The steering range was 187 times as wide as the tilting angle. In addition, both the direction and the frequency of the THz beam were simultaneously and independently controlled. The frequency tuning was achieved from 0.3 to 1.7 THz.