High efficiency submillimeter frequency multipliers

Solid-state sources have been developed for 330 and 500 GHz using cascaded varactor multipliers driven by a Gunn oscillator. The 330-GHz source uses a cascade of two balanced doublers, achieving very high efficiency, and produces an output of 4 mW. The 500-GHz source uses a cascade of a balanced doubler and single diode tripler and produces 0.7 mW. The doubler output at 330 GHz has been used to drive a harmonic mixer at 660 GHz, and plans are to drive yet another doubler at 660 GHz, where an output of 0.1-0.2 mW is expected. The output may prove to be enough LO for a cooled Schottky diode mixer. The tripled power at 500 GHz is quite sufficient for operation of Schottky diode mixers at this frequency and should be adequate as a pump source for a low-power doubler at 1 THz, such as would be used with a superconductor-insulator-superconductor (SIS) mixer.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>