Terahertz generation and detection with InGaAs-based large-area photoconductive devices excited at 1.55  μ m

We report on scalable large-area terahertz emitters and detectors based on In0.53Ga0.47As/In0.52Al0.48As heterostructures for excitation with 1.55 μm radiation. Different geometries involving three different electrode gap sizes are compared with respect to terahertz (THz) emission, bias field distribution, and Joule heating. The field distribution becomes more favorable for THz emission as gap size increases, while Joule heating exhibits the opposite dependence. Devices with three different gap sizes, namely 3 μm, 5 μm, and 7.5 μm, have been investigated experimentally, the emitter with a gap size of 7.5 μm showed the best performance. The scalable devices are furthermore employed as detectors. The scalable electrode geometry enables spatially integrated detection, which is attractive for specific applications, e.g., where an unfocused THz beam has to be used.