Design and characterization of evanescently-coupled photodiodes for 1.3 μm wavelength

The evanescently coupled waveguide photodiode (ECPD) has been fabricated and used for the generation of continuous-wave (CW) terahertz (THz) field at a 1.3 μm wavelength. We designed a matching layer to evanescently couple the optical beam from the base waveguide to the active region so as to get a high responsivity, 0.36 A/W. We also measured CW THz photocurrent at 350 GHz using log-periodic antenna-integrated ECPD as emitting photomixer. We get the signal-to-noise ratio of about 60dB.