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Proceedings Paper

Low-noise SIS mixer for far-infrared radio astronomy
Author(s): Alexandre Karpov; David Miller; Frank R. Rice; Jeffrey A. Stern; Bruce Bumble; Henry G. LeDuc; Jonas Zmuidzinas
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Paper Abstract

We present a low noise SIS mixer developed for the 1.2 THz band of the heterodyne spectrometer of the Herschel Space Observatory. With the launch of the Herschel SO in 2007, this device will be among the first SIS mixers flown in space. This SIS mixer has a quasi-optical design, with a double slot planar antenna and an extended spherical lens made of pure Si. The SIS junctions are Nb/AlN/NbTiN with a critical current density of about 30 KA/cm2 and with the junction area of a quarter of a micron square. Our mixer circuit uses two SIS junctions biased in parallel. To improve the simultaneous suppression of the Josephson current in each of them, we use diamond-shaped junctions. A low loss Nb/Au micro-strip transmission line is used for the first time in the mixer circuit well above the gap frequency of Nb. The minimum uncorrected Double Sideband receiver noise is 550 K (Y=1.34). The minimum receiver noise corrected for the local oscillator beam splitter and for the cryostat window is 340 K, about 6 hv/k, the lowest value achieved thus far in the THz frequencies range.

Paper Details

Date Published: 8 October 2004
PDF: 6 pages
Proc. SPIE 5498, Millimeter and Submillimeter Detectors for Astronomy II, (8 October 2004); doi: 10.1117/12.553190
Show Author Affiliations
Alexandre Karpov, California Institute of Technology (United States)
David Miller, California Institute of Technology (United States)
Frank R. Rice, California Institute of Technology (United States)
Jeffrey A. Stern, Jet Propulsion Lab. (United States)
Bruce Bumble, Jet Propulsion Lab. (United States)
Henry G. LeDuc, Jet Propulsion Lab. (United States)
Jonas Zmuidzinas, California Institute of Technology (United States)

Published in SPIE Proceedings Vol. 5498:
Millimeter and Submillimeter Detectors for Astronomy II
Jonas Zmuidzinas; Wayne S. Holland; Stafford Withington, Editor(s)

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