In a paper, published in Applied Physics Letters, we present a flexible holographic metasurface operating in the mm-wave range. The implementation of this metasurface is a three-layer structure using c-rings to encode the hologram and is implemented in both rigid and flexible designs. Furthermore, we present simulations and experimental results of the resultant holographic images. This work is of practical relevance for retrofitting existing mm-wave equipment for applications related to antennas (e.g. for 5G) and electromagnetic shielding.
In this paper, published in Annalen der Physik, we present the direct measurement of the nonlinear transmission matrix of complex materials, exploiting the strong optothermal nonlinearity of scattering silica aerogel. It is shown that the dephasing effects due to nonlinearity are both controllable and reversible, opening the road to applications based on the nonlinear response of random media
In this paper, published in ACS Nano, we present a platform for lithographically defining micron-sized features with flat tops in lead-haldide perovskites. Our method uses standard resists at low temperatures. Furthermore, we expand this platform to produce arrays of multi-colour pixels for commercial perovskite LED display applications.
In a remarkable display of timing, James Burch, Adam Fleming, and Xin Li have all passed their PhD Vivas within one week of each other! As is tradition, all three were soaked at the location of the now paved over Physics and Astronomy Pond. We wish all three the very best in their future careers, which include Patent Law, Systems Engineering, and Mobile Technology Design and Fabrication. James Burch, for a thesis entitled: Flexible Holographic Metasurfaces Adam Fleming, for a thesis entitled: Linear and Nonlinear Optical Properties of Silica Aerogel Xin Li, for a thesis entitled: Epsilon-Near-Zero Metamaterials for Optoelectronic Applications
In this paper, published in APL Photonics, we design and experimentally demonstrate an optical free-standing and low-loss epsilon-near-zero (ENZ) metamaterial which shows a vanishing effective permittivity at the visible range. We fabricate the flexible ENZ membrane using the sacrificial layer-assisted method by stacking polymer (SU-8) and silver nano-layers. The obtained membranes do not show any sign of degradation even after several thousand bending cycles (BCs). Additionally, we demonstrate that our ENZ material can conform to targets with a radius of curvature of a few microns. This material permits to coat any substrate or device with a tailored made “photonic skin”, decoupling the fabrication requirements from… Read More »Conformable optical coatings with epsilon near zero response
In a paper published in Nature Communications, we report on the integration of sub-micron semiconductor lasers in living cells. In this work, fruit of the collaboration with Malte Gather and his group at the University of St Andrews, we demonstrate that lasers with dimensions much smaller than that of many cell nuclei can be used to tag individual cells and sense their environment. This research paves the way for a new bio-photonics platform that will provide new insight into cell biology, including research in immune cells, neutrons and cancer cells. A. H. Fikouras, M. Schubert, M. Karl, J. D. Kumar, S. J. Powis, A. Di… Read More »Integration of sub-micron semiconductor lasers in living cells
Congratulations to James Burch and Alasdair Fikouras for taking 1st and 2nd Place respectively in the annual PhD assessment’s poster competition! James presented work on his flexible meta surface holograms, which are topologically sensitive and have applications in areas of security. Alasdair presented his work on Intracellular Photonic Nanodisks, as a way to place unique and trackable light sources within the cells themselves, providing improvements to current biological imaging methods.
In a paper published in APL Photonics we demonstrate the control of the emission of a GaAs quantum dot (QD) embedded in a GaAs/AlGaAs nanowire (NW) by the post-fabrication of a plasmonic grating on its surface. We fabricated a sub-wavelength Pt grating directly on the NW surface, via electron beam induced deposition, to enhance the emission efficiency of QD for the polarization parallel to the NW of 45%, with a 17% reduction in the photon lifetime. These findings and EBID approach offer great opportunities for the development of nanopatterned QD emitters and new hybrid nanophotonic platforms for efficient single photon sources.
“We are pleased that our work on conformable holographic metasurfaces have been featured on the cover of the special issue of ACS Photonics on photonic metasurfaces”.
In a paper published in ACS photonics, we present a flexible holographic metasurface with surface topology dependent functionality. We demonstrate that the phase contribution of the non-flat metasurface shape determines the symmetry properties of the far field holographic image. Here we also describe a framework to increase the sensitivity of the holographic image to the exact metasurface topology. This work is of practical relevance for security printing technologies, as well as surface polarization and surface topology sensors.