Towards integrated continuous wave THz systems

Abstract

We present a photonic integrated circuit, which enables the full control of the THz signal in continuous wave photomixing THz systems via standard electronics. The device comprises two DFB-lasers and an optical phase modulator on a single chip. Due to a unique bidirectional operation technique, the chip provides the optical beat signal for both THz emitter and THz receiver and allows for manipulation of the THz phase via the optical phase modulator. To evaluate the performance of our solution, we realize a coherent cw THz system based on our photonic integrated circuit and compare it to discrete lasers and standard components. As the results show, both setups feature an identical signal-to-noise ratio, reaching 50 dB at a frequency of 1 THz for an integration time of 500 ms. This is the best reported performance of CW photomixing systems running at 1.5 μm optical wavelength.