1.9-3.2 THz Schottky based harmonic mixer design and characterization

The development of a Schottky diode based 1:9 - 3:2 THz harmonic mixer with high conversion efficiency is described. The mixer will be used as part of an ambient receiver to enable phase locking of Quantum Cascade (QC) lasers. The mixer consists of quartz based LO, IF circuits and a GaAs based THz circuit with integrated diode. The RF input is a diagonal horn coupled to WM-86 rectangular waveguide, with size 86 μm by 43 μm. The waveguide is coupled to the diode using a waveguide probe with integral DC bias line. Measurements of the mixer were performed using a 2 THz solid state source and 2.5 THz Quantum Cascade(QC) laser, and yielded a conversion loss of 30 dB for 3rd harmonic mixing. This result is a 15 dB improvement from a previous harmonic mixer that was presented by our group.