Arrayed Continuous-wave THz Photomixers

TL;DR

This paper introduces arrayed continuous-wave THz photomixers that enable beam steering, increased power, and improved imaging capabilities through constructive interference and phase tuning, demonstrated over long distances and broad spectra.

Contribution

The work presents novel chip-scale and free space THz photomixer arrays with phase-controlled beam steering and enhanced power for spectroscopy and imaging.

Findings

Beam steering achieved via phase tuning of laser signals.

Constructive interference enhances focal intensity by N^2.

Arrays operate effectively over 70 GHz to 1.1 THz.

Abstract

We present both chip-scale and free space coherent arrays of continuous-wave THz photomixers. By altering the relative phases of the exciting laser signals, the relative THz phase between the array elements can be tuned, allowing for beam steering. The constructive interference of the emission of N elements leads to an increase of the focal intensity by a factor of NxN while reducing the beam width by ~1/N, below the diffraction limit of a single source. Such array architectures strongly improve the THz power distribution for stand-off spectroscopy and imaging systems while providing a huge bandwidth at the same time. We demonstrate this by beam profiles generated by a free space 2x2 and a 4x1 array for a transmission distance of 4.2 meters. Spectra between 70 GHz and 1.1 THz have been recorded with these arrays.