Title :
Quasi-optical NbN/AlN/NbN mixers in submillimeter wave band
Author :
Uzawa, Y. ; Wang, Z. ; Kawakami, A.
Author_Institution :
Lab. of Commun. Res., Kansai Adv. Res. Centre, Kobe, Japan
fDate :
6/1/1997 12:00:00 AM
Abstract :
We have designed, fabricated and evaluated a quasi-optical SIS receiver with NbN/AlN/NbN tunnel junctions in the submillimeter-wave region. The receiver consists of a planar self-complementary log-periodic antenna and MgO hyperhemispherical lens with an anti-reflection cap for RF optics, NbN SIS junctions and a radial short stub tuner to resonate out its capacitance for RF matching. The prepared NbN SIS junction has a current density of 20 kA/cm/sup 2/ and is about 1 /spl mu/m in diameter, supplying a small /spl omega/C/sub J/R/sub N/ product (/spl omega/C/sub J/R/sub N/=3 at 300 GHz). From 297 to 356 GHz the average double sideband (DSB) receiver noise temperature measured by using the standard Y-factor method was about 200 K. The lowest receiver noise temperature, 167 K (DSB), was obtained at around 303 GHz. These results suggest that our NbN SIS junctions can be used for terahertz mixer elements instead of Nb SIS junctions.
Keywords :
aluminium compounds; niobium compounds; submillimetre wave mixers; submillimetre wave receivers; superconducting device noise; superconductor-insulator-superconductor mixers; 297 to 356 GHz; DSB receiver noise temperature; MgO; MgO hyperhemispherical lens; NbN-AlN-NbN; NbN/AlN/NbN tunnel junction; RF matching; RF optics; Y-factor; anti-reflection cap; current density; planar self-complementary log-periodic antenna; quasi-optical SIS mixer; radial short stub tuner; submillimeter wave band; terahertz element; Capacitance; Current density; Lenses; Log periodic antennas; Measurement standards; Noise measurement; Optical receivers; Radio frequency; Temperature measurement; Tuners;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
