Tunable devices are the backbone of most of the modern technologies, they are used to modulate electromagnetic waves and signals in most modern devices. While the problem of such tunability is largely solved in microwaves and for optical frequencies, this functionality is highly sought after for Terahertz applications. Design and experiments with functional terahertz metamaterials is the direction that offers a range of fundamental and applied projects.
The electromagnetic properties of most ordinary materials is described by their refractive index, which greatly simplifies the calculation of wave propagation. In recent years, this concept has been extended so that artificially created micro and nano structures can be made small enough that they can also be described in the same way. The advantage of these structures is that they can achieve exotic behaviour not found in the optical properties of natural materials, including negative refraction, perfect lensing, backward waves, optical rotation, strongly nonlinear properties, highly tunable structures and many more. More importantly for applications and for our projects is that metamaterials can be made tunable, i.e. their properties can be modulated, e.g. by voltage or other external stimuli.
Depending on the length of your project (honours, masters or phd), you could include one or more of the following elements:
- Terahertz experiments: The terahertz wavelength range is a relatively unexplored part of the spectrum between microwave and near-infrared. There are many potential applications such as imaging, drug and explosive detection, which are expected to benefit from devices fabricated using metamaterial technology. We have a THz time-domain spectroscopy system which enables the measurement of metamaterial properties in this range.
- Theoretical modelling: The exotic properties of metamaterials mean that waves propagating in them can exhibit a range of interesting new properties. Examples include the "transformation optics", which make the wave behave as though space has been transformed.
- Numerical simulation: The design of metamaterials for experiments usually requires CAD modelling with advanced electromagnetic simulation software. This also shows how many exotic properties emerge in these systems.
- Micro fabrication: Since metamaterials must be small compared to the wavelength at which they operate, this means that THz structures must have dimensions in the tens of microns. We have access to state of the art facilities of the Australian Nanofabrication Facilities at ANU which provide students with necessary training and enable these structures to be created.