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Our goal is to engineer devices that achieve much higher performance and efficiency than conventional offerings.

The metamaterial concept has enourmously expanded what materials can do for us, realising that in addition to chemical composition, the fine structure of a conventional material can be designed at the outset to engineer bespoke and disruptively advantageous characteristics and functionality. This concept of function-through-structure has achieved huge traction in recent years particularly in microwaves, optics and acoustics, and is poised to radically transform the design, manufacture and functionality of everyday products. Our research exploits metasurfaces (two-dimensional counterpart of metamaterials), photonic cystals and plasmonics to access new physics through enhanced light-matter interaction and to provide new technological solutions for communication and sensing applications.

Microwave-to-infrared metasurfaces for communication and sensing technologies

Miguel Navarro-Cía, Rohit Chikkaraddy, Tom Siday

The field of topological photonics explores topology-related phenomena in the framework of electromagnetic waves (photons) rather than electrons as done in condensed matter physics. Due to the fundamental difference between photons and electrons, new physics and problems specific to the bosonic nature of light lead to new ways to do old things...and even new things such as scattering-immune one way signal transport supported by surface/edge states. From an engineering perspective, deep subwavelength, broadband, and electromagnetic robustness characteristics have profound implications for integrated circuitry. The exploitation of metamaterials in this context provides us vast degrees of freedom for realising various topological states immune to disorder and defects. 

The ability to manipulate the phase, amplitude and polarisation of electromagnetic waves with infinitesimal interaction length, makes metasurfaces promising platforms for integrated or miniaturised (and thus, lightweight!) solutions that are unreachable by traditional volumetric refractive and diffractive elements like gratings and lenses. Our focus in this strand is on realising metasurface-enabled surfaced-enhanced sensing platforms, and high-performance low-profile antennas and detectors.

From the characterisation point of view, this research is supported by commercial THz spectrometers (Toptica and Menlo), a confocal Raman microscope (Renishaw) and a microwave vector network analyser (Keysight) coupled to an xyz translation stage for automatic near-field mapping. From the fabrication point of view, we resort to two-photon polymerisation direct laser writting (Nanoscribe) and specalised fabrication collaborators.

Photonic crystals for quantum technologies

Angela Demetriadou

Quantum entanglement is an essential resource in quantum information science. It has been realised in various environments, even at ambient conditions, but often complex experimental setups make them undesirable for use in distributed networks. To address this challenge, we are championing the use of nanobeam photonic crystal waveguides with unprecedented quality factor (Q = 1x10⁷) and optical confinement (V < 0.6 Λ³) while operating at 780 nm for strong coupling with cold atoms. The waveguide nature of our designs allows us to scale up to an unprecedented number of qubits and are ideal for constructing large quantum networks, where both local and remote entanglement can be realised.

This research is facilitated by our workstations and ºÚÁϳԹÏÍø supercomputer BlueBEAR running electromagnatic software.

Nanoscale semiconductors for light detection and energy havesting applications

Andre Kaplan, Leigh Canham, Miguel Navarro-Cía

In 1990 Leigh Canham discovered strong visible photoluminescence from porous Si, and later demonstrated its in vitro biocompatibility and bioactive properties leading to significant research interest in the biomedical field. Resorting into this pioneering work, the group is embedding metallic nanoparticles in porous semiconductors to exploit their plasmonic response for light-matter interaction enhancement, looking at other application domains in sensing and energy havesting. 

The fabrication of this research is supported by our specialist knowledge in semiconductor anodisation in HF based solutions - photoassisted, periodically modulated and magnetic field assistend modalities. The characterisation strand is enabled by a commercial Brunauer-Emmett-Teller analyzer (Micromeritics) and fourier transform infrared spectrometer (Bruker), and beskpoke ultrafast spectroscopy setups, including a pump-probe time-resolved Z-scan, run with a commercial laser system (Coherent Ltd).

Key Experimental Techniques