IEEE Transactions on Applied Superconductivity

A low-noise 2.5 THz superconductive Nb hot-electron mixer

Boris S. Karasik, Michael C. Gaidis, William R. McGrath, B. Bumble, Henry George LeDuc

Published Jun 1, 1997• 32 citations

Abstract

We report on the development of a quasioptical Nb hot-electron bolometer mixer for a 2.5 THz heterodyne receiver. The devices are fabricated from a 12 nm thick Nb film, and have a 0.30 /spl mu/m/spl times/0.15 /spl mu/m in-plane size, thus exploiting diffusion as the electron cooling mechanism. The rf coupling was provided by a twin-slot planar antenna on an elliptical Si lens. A specially designed 2.5 THz system, using a CO/sub 2/-pumped FIR laser as local oscillator (LO), with rf hot/cold loads enclosed in vacuum to avoid atmospheric absorption, was used in the experiment. The experimentally measured double sideband (DSB) noise temperature of the receiver was as low as /spl les/3000 K, with an estimated mixer noise temperature of /spl ap/750 K. These results demonstrate the operation of the diffusion-cooled bolometer mixer above 2 THz.

DOI: 10.1109/77.622174

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