Demonstration of a low-distortion terahertz system-on-chip using a CPS waveguide on a thin membrane substrate

Distortion-free transmission of THz-bandwidth pulses over centimeter-scale distances is desirable for future THz system-on-chip (TSoC) applications. In this work we achieve this by utilizing a coplanar strip (CPS) transmission line fabricated on a thin (1 µm) silicon nitride membrane. To generate and detect the THz-bandwidth pulses we use a well-known lift-off technique to construct thousands of small (20 µm × 40 µm) thin-film LTG-GaAs photoconductive devices from a small (approx. 4 mm × 4 mm) substrate. The devices are then bonded to the CPS transmission line on the thin silicon nitride membrane, DC biased and optically pumped by a sub-picosecond laser. We demonstrate the generation and detection of a pulses containing frequencies up to 1.5 THz after propagating for 10 mm.