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Published June 2011 | public
Journal Article

Low Noise 1 THz SIS Mixer for Stratospheric Observatory: Design and Characterization

Abstract

We report the development of a low noise SIS mixer aimed for 1 THz channel of the Caltech Airborne Submillimeter Interstellar Medium Investigations Receiver (CASIMIR), designed for the Stratospheric Observatory for Far Infrared Astronomy (SOFIA). The mixer uses Nb/Al-AlN/NbTiN SIS junctions with critical current density of about 45 kA/cm^2. The junctions are shaped in order to optimize the suppression of the Josephson DC currents. We used a double slot planar antenna to couple the mixer chip with the telescope beam. The RF matching microcircuit is made using Nb and gold films. The mixer IF circuit is designed to cover 4-8 GHz band. The test receiver with the new mixer has the low noise operation in a 0.9-1.05 THz band. The minimum DSB receiver noise measured at 1 THz is 260 K (Y=1.64) , apparently the lowest reported up to date.

Additional Information

© 2011 IEEE. Manuscript received August 05, 2010; accepted February 21, 2011. Date of publication March 22, 2011; date of current version May 27, 2011. This work was supported by USRA SOFIA instrument development program. The authors thank John Ward (now at Raytheon), Frank Maiwald, Peter Bruneau, Alain Maestrini (now at Observatory de Paris), John Gill and Choonsup Lee for the help in preparation of the local oscillator chain used in this work.

Additional details

Created:
August 22, 2023
Modified:
March 5, 2024