Dr Isaac Luxmoore
EPSRC-UKRI Innovation Fellow and Senior Lecturer
Telephone: 01392 723685
Extension: (Streatham) 3685
Isaac Luxmoore studied Electronic Engineering at the University of Sheffield, gaining his PhD in 2009 for work on focused ion beam processing of superconducting and optoelectronic devices. Isaac subsequently joined the Physics Department at Sheffield, where he worked for four years on III-V semiconductor quantum dots, photonic crystals and nanophotonic integration. In 2012 Isaac joined the University of Exeter as a research fellow, working on graphene-based optoelectronic devices for mid-IR and THz applications, with a focus on graphene plasmonics, before taking on a Lectureship in May 2016. The common theme in Isaac’s research is nanofabrication, working with a wider range of materials and techniques. His current research interests are focused on the photonic integration of 2D materials for a range of applications, including quantum technology, THz devices and bio-sensing.
Graphene based mid-IR and THz optoelectronics
The THz portion of the electromagnetic spectrum bridges the gap between electronics and optics and provides a wealth of opportunity for technological exploitation in areas such as free space communication, security, bio-sensing and trace gas detection. Metamaterials provide a powerful tool for the manipulation of THz radiation, but the tunability required for switches and modulators is difficult to achieve in predominantly metal based devices. On the other hand, the ability to electrostatically control the charge density in graphene has enabled tunable and switchable plasmonic devices . Along with colleagues at Exeter and collaborators at ETH Zurich and the University of Augsburg, I have developed hybrid structures comprised of graphene plasmonic resonators coupled to complementary split-ring resonators (CSRR), thus demonstrating a highly tunable metamaterial, where the interaction between the two resonances reaches the strong-coupling regime. Such hybrid metamaterials have been employed in two applications; firstly as high-speed THz modulators, exhibiting ~60% transmission modulation and state-of-the-art operating speeds in excess of 40 MHz . This work gained significant media coverage, with reports in Electronics Weekly, Phys.org and The Engineer. Secondly, the hybrid metamaterials have been employed as photodetectors, operating in the mid-IR to THz. In this case, the CSRR is fabricated from two different metals and acts like a cavity to enhance the absorption of electromagnetic radiation by the graphene ribbon, whilst the asymmetric metal contacts enable photo-thermoelectric detection. The spectral response to the detectors is measured using FTIR spectroscopy and devices designed for the mid-IR demonstrate peak responsivity (referenced to total power) of ~100mV/W at 45THz. The detectors have been employed in the spectroscopic evaluation of vibrational resonances, thus demonstrating a key step towards a platform for integrated surface enhanced sensing .
Integrated Quantum Photonics with III-V Semiconductors
Indium Arsenide quantum dots have significant potential for photonic quantum technologies, such as quantum computing and quantum metrology, where they have potential as isolated qubits and as a source of indistinguishable single photons and entangled photons. My work was focused on the integration of quantum dots with photonic components, vital for practical applications, with a highlight the demonstration of a waveguide geometry for the in-plane transfer and read-out of a quantum dot spin-state , work which was featured in Nature Photonics and was the first report of chiral light-matter interaction in nanophotonic waveguides. In addition, I have made important contributions to coherent control of QD spin qubits ; integrated quantum photonics ; photonic crystal cavities and waveguides [7, 8]; and made the first demonstration of single photon emission from InAs/GaAs quantum dots, and the first strongly-coupled quantum dot system, on Silicon .