IEEE Transactions on Applied Superconductivity

Development of Low Noise THz SIS Mixer Using an Array of Nb/Al-AlN/NbTiN Junctions

Alexandre Karpov, D. Miller, Jeff A. Stern, B. Bumble, Henry George LeDuc, Jonas Stasys Zmuidzinas

Published Jun 1, 2009• 6 citations

Abstract

We report the development of a low noise and broadband SIS mixer aimed for 1 THz channel of the Caltech Airborne Submillimeter Interstellar Medium Investigations Receiver (CASIMIR), designed for the Stratospheric Observatory for Infrared Astronomy, (SOFIA). The mixer uses an array of two 0.24 mum2Nb/Al-AlN/NbTiN SIS junctions with the critical current density of 30-50 kA/cm2. An on-chip double slot planar antenna couples the mixer circuit with the telescope beam. The mixer matching circuit is made with Nb and gold films. The mixer IF circuit is designed to cover 4-8 GHz band. A test receiver with the new mixer has a low noise operation in 0.87-1.12 THz band. The minimum receiver noise measured in our experiment is 353 K (Y = 1.50). The receiver noise corrected for the loss in the LO injection beam splitter is 250 K. The combination of a broad operation band of about 250 GHz with a low receiver noise makes the new mixer a useful element for application at SOFIA.

DOI: 10.1109/tasc.2009.2017913

Related papers

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

Alexandre Karpov, D A Miller, J. A. Stern +5 more

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/cm2. 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.

IEEE Transactions on Applied SuperconductivityMar 22, 20116 citations

Low noise 1.4 THz SIS mixer for SOFIA

Alexandre Karpov, D. Miller, Jeff A. Stern +3 more

We report on the development of a 1.4 THz SIS mixer. The mixer uses SIS junctions made off Nb/AlAlN/NbTiN. The junction area is 0.24 μm and the RNA= 6 Ohm μm. The junctions are diamond-like shaped in order to optimize the suppression of the Josephson DC currents. We are using a double slot planar antenna to couple the mixer chip with the telescope beam. The matching microcircuit is made of Nb and gold. The on-chip coupling prediction is plotted below in the Fig. 1. The mixer is expected to provide a low noise operation in a 1.3 – 1.5 THz receiver. The mixer IF circuit is designed to cover 4 8 GHz band. The 1.3-1.5 THz SIS mixer is aimed for the 1.4 Terahertz channel of the Caltech Airborne Submillimeter Interstellar Medium Investigations Receiver (CASIMIR). It is a far-infrared and submillimeter heterodyne spectrometer, designed for the Stratospheric Observatory For Infrared Astronomy, (SOFIA). The goal of this work is to provide a low noise spectrometer particularly for the studies of the H2D 101 000 line around 1370 GHz. The mixer test with a limited LO power allows us to make an estimation of very good receiver performance with a higher LO levels (fig.2). The mixer test with a more powerful LO source is under way and will be presented.

Apr 1, 20081 citation

Development of 1THz SIS mixer for SOFIA

Alexandre Karpov, David A. B. Miller, Jeff A. Stern +3 more

We report the development of a low noise and broadband 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). In the SIS mixer are used the Nb/AlN/NbTiN junctions with the Josephson critical current density of about 40 KA/cm . The mixer is built using a double-slot quasi-optical design and covers a 250 GHz band centered at 1 THz. The minimum measured receiver noise is about 353 K (Y=1.50). The receiver noise may be reduced using a higher level of LO power. The developed mixer will allow building a receiver with the noise temperature approaching 250 K in 1 THz band and having a broader operation band compared to the previously reported.

Jan 1, 20073 citations

Low Noise 1 THz–1.4 THz Mixers Using Nb/Al-AlN/NbTiN SIS Junctions

Alexandre Karpov, D. Miller, F. Rice +4 more

We present the development of a low noise 1.2 THz and 1.4 THz SIS mixers for heterodyne spectrometry on the Stratospheric Observatory For Infrared Astronomy (SOFIA) and Herschel Space Observatory. This frequency range is above the limit for the commonly used Nb quasi particle SIS junctions, and a special type of hybrid Nb/AlN/NbTiN junctions has been developed for this project. We are using a quasi-optical mixer design with two Nb/AlN/NbTiN junctions with an area of 0.25. The SIS junction tuning circuit is made of Nb and gold wire layers. At 1.13 THz the minimum SIS receiver uncorrected noise temperature is 450 K. The SIS receiver noise corrected for the loss in the LO coupler and in the cryostat optics is 350-450 K across 1.1-1.25 THz band. The receiver has a uniform sensitivity in a full 4-8 GHz IF band. The 1.4 THz SIS receiver test at 1.33-1.35 THz gives promising results, although limited by the level of available LO power. Extrapolation of the data obtained with low LO power level shows a possibility to reach 500 K DSB receiver noise using already existing SIS mixer.

IEEE Transactions on Applied SuperconductivityJun 1, 200759 citations

Low-noise SIS mixer for far-infrared radio astronomy

Alexandre Karpov, David Miller, F. Rice +4 more

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.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEOct 8, 200425 citations

Low noise 1.2 THz SIS mixer for Herschel radio observatory

Alexandre Karpov, David A. B. Miller, F. Rice +4 more

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/A1N/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.

Jan 1, 20091 citation