(1) Terahertz Sensing and Imaging Laboratory, Advanced Science Institute, RIKEN, 519-1399 Aramaki-Aoba, Aoba-ku, Sendai Miyagi, 980-0845, Japan;(2) Nagoya University, Furocho, Chikusa-ku, Nagoya Aichi, 464-8603, Japan
Abstract:
We have investigated the characteristics of a terahertz (THz) beam steering method based on a combination of difference-frequency
generation (DFG) with the principle of the phased array antenna. In the DFG of THz radiation from a nonlinear optical crystal
pumped by optical beams, the phase front of the THz radiation is indirectly tilted by adjusting the relative incidence angle
between the pump beams to the crystal. A magnification of the steering angle with a factor of 193 is demonstrated as the most
important effect provided by the method. The effect allows the use of a high-speed optical deflector for adjusting the incidence
angle, accelerating the steering more than a hundred times compared with mechanical methods. The phase mismatching between
the THz radiation and the pump beams as well as the refraction at the crystal surface limit the steering angle of the THz
radiation to 56°, full width at half maximum.