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Infrared imaging and sensing: the single-photon frontier

Periodic Reporting for period 3 - IRIS (Infrared imaging and sensing: the single-photon frontier)

Reporting period: 2018-06-01 to 2019-11-30

Infrared imaging and sensing: the single-photon frontier (IRIS)

SUMMARY OF CONTEXT

Infrared sensing technology has a central role to play in addressing 21st century global challenges in healthcare, security and environmental sensing. Promising new applications hinge on the ability to detect individual quanta of light: single photons. At infrared wavelengths this is a formidable task due to the low photon energy, and commercial-off-the-shelf technologies fall far short of the required performance. The ambitious goal of IRIS was to engineer revolutionary photon counting infrared imaging and sensing solutions, with unprecedented spectral range, efficiency, timing resolution and low noise, using state-of-the-art materials and nanofabrication techniques. IRIS harnessed space age cryogenic technology to create compact and mobile detector systems. IRIS has enabled deployment these systems for the first time in revolutionary infrared imaging and sensing applications, including dosimetry for laser based cancer treatment and single photon atmospheric remote sensing.

OBJECTIVES

The objectives of IRIS were as follows:
1. To develop high performance near- to mid-infrared photon counting detectors, exploiting the remarkable materials properties of nanostructured superconductors.
2. To engineer practical and compact cryogenic detector systems.
3. To deploy these next generation detector systems in revolutionary imaging and sensing applications in the domains of healthcare, remote sensing and geothermal energy.
IRIS was conceived and led by Professor Robert Hadfield who is a recognised international leader in this field. The project is hosted by the James Watt School of Engineering at the University of Glasgow, UK.

Work package 1 Focused on evaluation and optimisation of detector materials, benchmarking of photon counting performance and scale up to large area photon counting arrays. Significant progress was made on materials development. A range of crystalline and superconducting materials were deposited by sputtering and atomic layer deposition and studied in detail. In addition photodetection in two dimensional superconductors was studied for the first time. Work is ongoing to scale up nanowire detectors to multipixel photon counting arrays and develop readout schemes. This ambitious work will continue through several major new UK grant awards aligned to the next phase of the UK National Quantum Technology Programme.

Work package 2 was carried out in close collaboration with STFC Rutherford Appleton Laboratory. We achieved a major breakthrough by demonstrating a superconducting nanowire single-photon detector mounted in a miniaturized cooler operating a few degrees above absolute zero. This was unveiled at the UK Quantum Technology Showcase in Westminster in November 2016. This work was published in a high impact publication. US, Chinese and Japanese groups have subsequently reported development work following our direction. Using IRIS support STFC Rutherford Appleton Laboratory have continued development work on their Stirling cooler design, as a first step towards a design suitable for massed manufacture.

Work package 3 focused on opening up emerging infrared photon counting applications. Particular progress was made in extending detector performance from near to mid infrared wavelengths. Reliable detection efficiency measurements were possible through a new laboratory testbed based around an optical parametric oscillator source. We have demonstrated superconducting nanowire detectors for single-photon laser ranging (LIDAR) in the mid infrared and used these detectors to enable photon pair source characterization in the mid infrared. In tandem we have made considerable progress on singlet-oxygen luminescence detection, achieving signal collection by several orders of magnitude. This technique could be applied in dose monitoring for photodynamic therapy in the treatment of cancer.
The IRIS project led to two notable scientific and technological breakthroughs:

1. The demonstration of a miniaturized cooling platform for superconducting single photon detectors at the UK National Quantum Technology Showcase in November 2016 was recognised as a tour de force and created considerable interest. Laboratories in China, Japan and US have followed up on our breakthrough work. This has led to plenary, invited and keynote talks at major international conferences. Professor Hadfield was awarded a visiting Professorship in Sweden, Fellowships of the Optical Society of America and the Royal Society Edinburgh and the James Joule Medal of the Institute of Physics.

2. Our painstaking work on superconducting nanowire single-photon detectors device development and calibrating these devices in the challenging mid infrared spectral region bore fruit in the final stages of IRIS. This has led to a groundbreaking mid infrared photon counting laser ranging (LIDAR) demonstration and opening up the mid infrared window for quantum optics.
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