Development of novel millimetre and submillimetre-wave quasi-optical devices based on metamaterials (astronomy)

The properties of the materials in nature 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-dimesional 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) is world-leading in the design
and production of quasi-optical devices based on a particular type of
metamaterials, those related to the mesh-filter technology. This technology,
developed by the academics of this group, is leading to the production of
different novel quasi-optical devices that, just a few years ago, would not be
dreamt possible. The extremely high accuracy that we can achieve in the
design, 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.
A large variety of devices can be developed by using the mesh-technology.
For example, artificial birefringent materials can be designed to build quasioptical
retarders such as Half-Wave Plates (HWPs, Fig.1). It is possible to
design generic devices able to manipulate the amplitude and the phase of the
electromagnetic radiation passing through it. In addition, this can be done
locally, i.e. arbitrarily varying the properties across the surface. Using this
method, we have recently developed ‘mesh-lenses’ able to reproduce the
behaviour of classical dielectric lenses, with the advantage of being flat and
thin devices (Fig.2).
In this project we propose to develop novel quasi-optical devices for millimetre
and sub-millimetre wavelength applications. There are many possible study
options:
a) Very large bandwidth mesh-HWPs
b) Large diameter mesh-lenses
c) Devices able to manipulate the Orbital Angular Momentum (OAM) of
the 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) Dispersive metamaterials
h) Artificial Magnetic surfaces
The ’metamaterials’ modelling will be carried out by using electromagnetic
finite element analysis software, such as Ansoft HFSS (see example in Fig.2).
Additional codes will be developed to design the specific quasi-optical
devices. These will be manufactured within the group facilities and then tested
using coherent detection with a Vector Network Analyser.
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, etc..
The PhD research project will consist of:
- Finite-element analysis electromagnetic modelling (Ansys HFSS)
- Design of a novel device
- Following the clean-room device manufacture
- Device testing with Vector Network Analyser
- Analysis and interpretation of the data