Generation of CW 0.5 THz radiation by photomixing the output of a two-colour 1.49 µm Fabry-Perot diode laser

A compact continuous-wave (CW) terahertz source is demonstrated using a single two-colour laser diode and a photomixer. The 350 µm-long Fabry-Perot laser is constrained to oscillate on non-adjacent cavity modes, at a frequency separation of 485 GHz, by the introduction of features along its ridge waveguide. At a drive current of 155 mA, more than 10 mW of CW power is delivered into a standard singlemode fibre. This radiation drives a waveguide photomixer, which incorporates an InGaAsP photodiode, to emit about 20 nW at the 485 GHz beat frequency.