Superconducting optical photon-counting detectors for astronomy

Lead Research Organisation: University of Cambridge
Department Name: Physics


Superconducting detectors are used extensively for astronomy throughout most of the electromagnetic spectrum: submillimetre-wave to X-ray. They have not, however, displaced CCD's in the optical part of the spectrum despite their ability to achieve time-resolved optical photon counting spectroscopy. There is one Group in the US that is working on optical superconducting imaging arrays, and they largely dominate the field. The purpose of the PhD project is to carry out modelling, manufacture, and testing of optical KIDs. We already have devices manufactured, which we have never tested, and so the work can get off to a rapid start. A key part of the project will be to build up the infrastructure needed for testing the optical behaviour of devices at low temperatures. The work will focus on understanding the physics of optical KIDs, particularly with respect to how to achieving high optical efficiencies. We have considerable experience in understanding the the non-equilibrium behaviour of superconductors under microwave and optical illumination , and the dynamical behaviour of superconducting resonators on membranes, and this understanding can be used to underpin our analysis of photon-counting KIDs. The devices we currently manufacture comprise resonators on membranes, and superconducting optical absorbers with integrated backing reflectors, and the PhD will focus on modelling and measuring these devices. In due course, the student will design and manufacture a second generation of devices. This work will be carried out in collaboration with a number of international organisations.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
ST/N50399X/1 01/10/2015 31/03/2021
1641674 Studentship ST/N50399X/1 01/10/2015 31/03/2019 Dan Moinard
ST/R504671/1 01/10/2017 30/09/2021
1641674 Studentship ST/R504671/1 01/10/2015 31/03/2019 Dan Moinard
Description NanoDTC Associate Studentship
Amount £3,000 (GBP)
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 02/2016 
Title Application of Energy Absorption Interferometry to infrared detectors and optical fibers 
Description Using the experimental system for Energy Absorption Interferometry I have designed and built, I applied the method to a set of infrared detectors. Single-source beam-pattern measurements and two-source fringe scans were performed. In particular, these measurements were repeated on one detector in 6 cases where the detector was coupled to optical fibres with different modal behaviours. These include custom-built arrays of tightly-packed optical fibres, in order to improve several measurement characteristics. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? No  
Impact The analysis of this data proves that Energy Absorption Interferometry is capable of characterizing the modal behaviour of a range of detectors and systems under test. This includes differentiating between single-mode, few-mode and multi-mode devices; superior measurements were obtained using tightly-packed fibre arrays. 
Title Design and construction of an experimental system for Energy Absorption Interferometry at infrared wavelengths 
Description I wrote a Matlab implementation of the Energy Absorption Interferometry theoretical model, which was developed and published by members of my group (including Prof. Stafford Withington) in recent years. In particular, this numerical model was used to simulate the behaviour of experimental systems. A large range of properties were investigated, including spatial resolution requirements for motorized stages used to scan infrared sources illuminating the device under test. The results obtained guided the design of an experimental apparatus for applying Energy Absorption Interferometry to infrared detectors. 
Type Of Technology Physical Model/Kit 
Year Produced 2016 
Impact I proposed and coordinated the purchase of commercially available components, as well as the manufacture of custom components by technicians in the group. The experimental system designed was constructed and is operational. 
Title Theoretical development and numerical implementation of an algorithm to reconstruct a matrix with missing data 
Description We used the specific features of the problem - missing data along the diagonal and sub-diagonals of a matrix - to elaborate a new algorithm to infer the missing datapoints. 
Type Of Technology New/Improved Technique/Technology 
Year Produced 2019 
Impact The theoretical foundations of the method were developed; a suitable algorithm was successfully implemented and its strengths and limitations were investigated using toy-model datasets. The algorithm was then successfully applied a large variety of experimental datasets.