THz beam steering by optical coherent control

TL;DR

This paper demonstrates a method for steering terahertz beams by controlling the phase of femtosecond laser pulses that excite photocurrents in GaAs, achieving about 8 degrees of beam deflection.

Contribution

It introduces a novel optical coherent control technique for dynamic THz beam steering using phase manipulation of ultrafast photocurrents.

Findings

Achieved approximately 8 degrees of THz beam steering.

Developed a dipole-based model relating photocurrent amplitudes to steering.

Showed phase control modifies emission patterns effectively.

Abstract

We demonstrate optical coherent control of the emission direction of THz radiation. Femtosecond laser pulses are used to excite different types of ultrafast photocurrents along different directions in a bulk GaAs sample. The overall emission pattern can be modified by changing the phase of the optical excitation. With this method, THz beam steering of about 8 degrees is realized. A simple dipole-based model allows us to relate the size of the steering effect to the amplitude ratio between the different photocurrent contributions and to diffraction effects resulting from the excitation spot size.