Multi-spectral terahertz interferometric imaging based on a monolithic retroactive silicon chip

This paper presents a multi-spectral interferometric method to coherently emit and detect multiple terahertz tones on the same antenna equipped silicon chip without the need of external elements. The method consists of exploiting the reciprocal properties of optical, electromagnetic and electrical components of a silicon integrated terahertz harmonic oscillator allowing it to operate as a source and detector in the same time. We name this method retroactive detection or imaging in contrast with traditional active terahertz imaging systems where a distinct source and detector are needed, this retroactive approach eliminate the need of additional terahertz components. By detecting the reflected terahertz waves on a remote target, images of a coin surface are produced at 0.35 THz, 0.7 THz, 1.05 THz and 1.4 THz. The device operates at room temperature in a continuous-wave mode.