Development of novel quasi-optical devices based on metamaterials for millimeter and sub-mm wave applications

The properties of natural materials are determined by how the atoms respond to electric and magnetic fields. Their average behaviour is summarised in the permittivity and permeability values associated with them. However, in principle it is possible to create artificial materials building periodic three-dimensional structures where the sub-wavelength unit elements are designed to respond strongly to the electromagnetic radiation. These ’metamaterials’ can be made by using planar metallic grids deposited on dielectric substrates stacked together to form three-dimensional structures.
The Astronomy Instrumentation Group (AIG), within the School of Physics and Astronomy, is world-leading in the design and production of metamaterial devices based on the ‘mesh-filters’ technology. This technology, developed by the academics of this group, has led to the invention of many novel quasi-optical devices that, just a few years ago, would not be dreamt possible. Birefringent metamaterials have been designed to realise ‘mesh half-wave plates’ (HWPs). Inhomogeneous surfaces, designed to locally and arbitrarily manipulate the amplitude and the phase of the electromagnetic radiation passing through them, have been employed to build ‘mesh-lenses’. The latter devices are able to mimic the behaviour of classical dielectric lenses with the advantage of being flat and very thin. Very accurate modelling combined with the manufacturing skills and expertise of the people working in our cleanrooms allow us to push further this field by designing new and more exotic devices.
In this project we propose to develop one of the following quasi-optical devices for millimetre and sub-millimetre wavelength applications:
a) Very large bandwidth mesh-HWPs
b) Large diameter mesh-lenses (Fresnel-type)
c) Devices able to manipulate the Orbital Angular Momentum (OAM) of light
d) Devices able to perform ‘hardware’ mathematical operations such as spatial differentiation, integration or convolution across the profile of an incoming beam
e) Horn antennas based on metamaterials
f) Negative refractive index and near-zero permittivity metamaterials
g) Artificial Magnetic surfaces

The ’metamaterials’ modelling will be carried out by using electromagnetic finite element analysis software (Ansys HFSS). Additional codes might be developed to design specific devices. These will be manufactured within the group facilities and then tested using Fourier Transform Spectrometers (FTSs) and Vector Network Analysers (VNAs). The applications of these devices range from mm and sub-mm astronomy, such as future space mission dedicated to CMB B-mode polarisation, to telecommunications, radar systems and security applications.
The PhD research project will consist of:
• Metamaterials electromagnetic modelling using finite-element analysis software (HFSS)
• Design of a novel quasi-optical device
• Assistance in the manufacture of the device within the group facilities
• Testing of the device with FTSs and VNAs
• Analysis and interpretation of the data