The SPLICE project enables the combined expertise of a wide range of experts to be brought to bear on the challenge of delivering QLM’s revolutionary quantum gas camera to the market. In this article, Jolyon De Freitas, Technical Lead for the Compound Semiconductor Applications Catapult on the SPLICE project, explains how CSAC is making the whole far greater than the sum of its parts.
The SPLICE project enables the combined expertise of a wide range of experts to be brought to bear on the challenge of delivering QLM’s revolutionary quantum gas camera to the market. In this article, Jolyon De Freitas, Technical Lead for the Compound Semiconductor Applications Catapult on the SPLICE project, explains how CSAC is making the whole far greater than the sum of its parts. Contact Jolyon at firstname.lastname@example.org.
The CSA Catapult is a high-tech innovation facility focused on helping UK industry exploit the advances made in compound semiconductor (CS) technologies. It brings to industry its MCIV concept – Modelling, Characterisation, Integration and Validation (Fig. 1). These are underpinned by four major pillars: Advanced Packaging; the Design Studio; RF, Power and Photonics Domain CS expertise; and an Evaluation laboratory.
The CSA Catapult has been providing the SPLICE consortium, and to date its Lead partner QLM, with modelling, characterisation and validation capabilities for their quantum gas sensing technology. SPLICE seeks to develop low-cost, high resolution instrumentation that provides 4D (3 spatial dimensions and time) images of gas leakages and plumes based on single photon gas detection quantum techniques. Using the latest innovation in LiDAR technologies, the instrumentation will be able to identify and map out the movement of trace gases across refineries, industrial gas production facilities and environmental sites. This technology will significantly improve the management and reduction of any negative environmental impact of leakage and trace gases from a Regulatory perspective.
Working hand in hand with the CSA Catapult, QLM were able to characterise and validate their compound semiconductor laser source for CO₂ gas absorption spectral lines utilising one of our wideband (300nm to 1700nm), picometre resolution spectrometers.
While this calibration exercise has been a success, detecting single photons in the short-wave infrared (SWIR, typically 900nm to 1700nm) can be problematic . To be able to detect SWIR photons having lower energies than those in the visible spectrum, requires complex bandgap engineering techniques . The most common photon counting detectors for the SWIR range are Indium Gallium Arsenide/Indium Phosphide (i.e. InGaAs/InP-based) single photon avalanche detectors (popularly known as SPADs) [1,3]. However, photon counting is bedevilled by relatively high dark count rates (DCRs), afterpulsing and in general, low photon detection efficiencies (PDEs). These are quite similar to those seen in traditional vacuum-based photomultiplier tubes (PMTs) [4,5].
The Catapult has therefore developed a SPAD Testbed and is working with QLM to characterise this type of emerging quantum detection technology. Measurements include, for example, DCR, PDE, timing resolution, I-V characteristics and their dependence on temperature. The lab facility is fitted with a number of modern equipment around high-resolution (~50ps) time-correlated single photon counting (TCSPC) hardware and software. The Testbed is expected to be used to characterise SWIR SPADs being designed and fabricated later in the SPLICE programme.
The CSA Catapult is also tackling a number of other R&D questions on the SPLICE programme. These include, for example, what other gases of industrial and environmental relevance might we bring to bear on this new quantum technology, and what is the nature of failure in certain photonic components.
As such, the Catapult continues to tie strong bundles – effectively SPLICE-ing it together with industry to achieve a stronger, more competitive UK economy.
 J Zhang, M Itzler, H Zbinden, J-W Pan (2015) Advances in InGaAs/InP single-photon detector systems for quantum communications. Light: Science & Applications 4 e286
 P Christol, J-B Rodriguez (2014) Progress on Type-II InAs/GaSb superlattice (T2SL) infrared photodetector: from MWIR to VLWIR spectral domains. International Conference on Space Optics — ICSO 2014, (Ed.) Zoran Sodnik, Nikos Karafolas, Bruno Cugny, Proc. of SPIE Vol. 10563, 105632C
 K Linga, Y Yevtukhov, BLiang (2009) Near Infrared Single Photon Avalanche Detector with Negative Feedback and Self Quenching. Proc. SPIE 7419, Infrared Systems and Photoelectronic Technology IV, 74190O (27 August 2009); doi: 10.1117/12.826908
 A Tosi, A Dalla Mora, F Zappa, S Cova, Sergio (2007) Germanium and InGaAs/InP SPADs for Single-Photon Detection in the Near-Infrared. Advanced Photon Counting Techniques II, Wolfgang Becker (Ed), Proc. Of SPIE Vol. 6771, 67710P doi: 10.1117/12.734961
 Photomultiplier Tubes, 3a Edition, 2007. Hamamatsu Photonics K.K. Ch. 4
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