Optical Efficiencies of Lens-Antenna Coupled Kinetic Inductance Detectors at 220 GHz

We have been developing a terahertz camera based on antenna-coupled superconducting resonators, the so-called microwave kinetic inductance detectors (MKIDs), and a silicon lens array. The MKID consists of a coplanar waveguide coupled to a double slot antenna and is patterned on a high-quality aluminum film grown by molecular beam epitaxy. The camera is sensitive at frequencies of 200-240 GHz. Its bandwidth is limited by the impedance properties of the double slot antenna. The design, fabrication, and optical evaluations of the planar antennas and silicon lens arrays are presented in this paper. The MKID camera has been evaluated both in dark conditions and under optical radiation in a 0.1-K dilution refrigerator. The electrical noise equivalent power was around 5×10-18 W/√(Hz) in dark conditions and 4×10-16 W/√(Hz), which is much lower than the photon noise level, with the optical load. The optical efficiency of the camera was estimated by three independent methods, and the results were consistent with each other and equal to 20%-25% without an anti-reflection coating on the lens surface.

[1]  J. Zmuidzinas,et al.  Equivalence of the Effects on the Complex Conductivity of Superconductor due to Temperature Change and External Pair Breaking , 2008 .

[2]  Gabriel M. Rebeiz,et al.  Double-slot antennas on extended hemispherical dielectric lenses , 1992 .

[3]  R. Barends.  Photon-detecting superconducting resonators , 2009 .

[4]  J. J. A. Baselmans,et al.  Photon noise limited radiation detection with lens-antenna coupled microwave kinetic inductance detectors , 2011, 1107.4330.

[5]  P. Vielva,et al.  Limits on the detectability of the CMB B-mode polarization imposed by foregrounds , 2004, astro-ph/0411567.

[6]  T M Klapwijk,et al.  Number fluctuations of sparse quasiparticles in a superconductor. , 2011, Physical review letters.

[7]  Andrey M. Baryshev,et al.  Antenna coupled Kinetic Inductance arrays for space and ground based imaging arrays , 2009 .

[8]  P. Richards,et al.  A cryogenic blackbody for millimeter wavelengths , 1984 .

[9]  David Montgomery,et al.  SCUBA-2: engineering and commissioning challenges of the world's largest sub-mm instrument at the JCMT , 2010, Astronomical Telescopes + Instrumentation.

[10]  Ki Won Yoon,et al.  Progress Toward Corrugated Feed Horn Arrays in Silicon , 2009 .

[11]  J. J. A. Baselmans,et al.  Long quasiparticle lifetime in Aluminum Microwave Kinetic Inductance Detectors using coaxial stray light filters , 2009 .

[12]  G. Gerini,et al.  Progress in Antenna Coupled Kinetic Inductance Detectors , 2011, IEEE Transactions on Terahertz Science and Technology.

[13]  P. K. Daya,et al.  Antenna-coupled microwave kinetic inductance detectors , 2006 .

[14]  Yutaro Sekimoto,et al.  Development of Crystal Al MKIDs by Molecular Beam Epitaxy , 2012 .

[15]  Jonas Zmuidzinas,et al.  Quasi-optical slot antenna SIS mixers , 1991 .

[16]  R. Barends,et al.  Quasiparticle relaxation in optically excited high-Q superconducting resonators. , 2008, Physical review letters.

[17]  J. J. A. Baselmans,et al.  Enhancement of quasiparticle recombination in Ta and Al superconductors by implantation of magnetic and nonmagnetic atoms , 2009 .

[18]  Anthony J. Peacock,et al.  Quasiparticle-phonon downconversion in nonequilibrium superconductors , 2000 .

[19]  H. Leduc,et al.  A broadband superconducting detector suitable for use in large arrays , 2003, Nature.

[20]  R. Simons.  Coplanar waveguide circuits, components, and systems , 2001 .