Waveguide-Type SIS Receiver Using All-NbN Technique

This paper describes the first experimental results for a waveguide-type all-NbN superconductor-insulator-superconductor (SIS) heterodyne mixer on an MgO substrate designed to operate over the gap frequency of Nb. The mixer consists of an NbN/MgO/NbN junction, which has a length of one wavelength at 880GHz as a tuning circuit, an NbN/MgO/NbN microstrip as a λ/4 impedance transformer, and an RF choke filter. The mixer chip was designed using a high-frequency-structure simulator. Its return-loss and embedding-impedance characteristics were examined using a 180-times-scaled mixer model. By optimizing the cutting and polishing processes for the MgO substrate, we were able to fabricate the mixer chip with an accuracy of less than 5 μm. We succeeded in mounting the chip on a mixer block and in estimating the receiver noise temperature. The uncorrected minimum double-sideband receiver noise temperature was 740 K at 824 GHz. A comparison of the receiver noise temperature in a quasi-optical SIS mixer fabricated on the same wafer as the waveguide mixer showed that input noise was the major contributor to receiver noise in the waveguide mixer.

[1]  Marc J. Feldman,et al.  Quantum detection at millimeter wavelengths , 1985 .

[2]  P. Dieleman,et al.  Shot noise beyond the Tucker theory in niobium tunnel junction mixers , 1998 .

[3]  Zhen Wang,et al.  A Tuning Circuit with Two Half-Wave Distributed Junctions for All-NbN SIS Mixers , 2003 .

[4]  Antti V. Räisänen,et al.  Scaled model measurements of embedding impedances for SIS waveguide mixers , 1985 .

[5]  Yoshinori Uzawa,et al.  Superconducting properties and crystal structures of single‐crystal niobium nitride thin films deposited at ambient substrate temperature , 1996 .

[6]  R. J. Wylde,et al.  Millimetre-wave Gaussian beam-mode optics and corrugated feed horns , 1984 .

[7]  Raymond Blundell,et al.  A 600-700 GHz Resonant Distributed Junction for a Fixed-Tuned Waveguide Receiver , 2002 .

[8]  Yoshinori Uzawa,et al.  Development of epitaxial NbN/MgO/NbN–superconductor-insulator-superconductor mixers for operations over the Nb gap frequency , 2003 .

[9]  J. W. Kooi,et al.  230 and 492 GHz low noise sis waveguide receivers employing tuned Nb/AlOx/Nb tunnel junctions , 1994 .

[10]  Shigehito Miki,et al.  Fabrication and characterization of epitaxial NbN/MgO/NbN Josephson tunnel junctions , 2001 .

[11]  Y. Uzawa,et al.  NbN/AlN/NbN tunnel junctions fabricated at ambient substrate temperature , 1995, IEEE Transactions on Applied Superconductivity.

[12]  Yoshinori Uzawa,et al.  Performance of all-NbN quasi-optical SIS mixers for the terahertz band , 2001 .

[13]  Andrey M. Baryshev,et al.  Low-noise 1 THz superconductor–insulator–superconductor mixer incorporating a NbTiN/SiO2/Al tuning circuit , 2001 .

[14]  Takashi Noguchi,et al.  Design Consideration for a Two-Distributed-Junction Tuning Circuit , 2004 .

[15]  W. Zhang,et al.  Scaled model measurement of the embedding impedance of a 660-GHz waveguide SIS mixer with a 3-standard deembedding method , 2003, IEEE Microwave and Wireless Components Letters.

[16]  A. Karpov,et al.  A three photon noise SIS heterodyne receiver at submillimeter wavelength , 1999, IEEE Transactions on Applied Superconductivity.