Research Streams

A metasurface is a planar structure comprising a periodic array of sub-wavelength metallic or dielectric resonators. Strong interaction between incident electromagnetic waves with these resonators yields great control over the amplitude, phase, and polarisation. Metasurfaces can perform a variety of functions that are either unprecedented or superior to those available from conventional optics. These capabilities are specially important for the terahertz domain, where natural materials with desirable properties are scarce. As such, our goal is to leverage these concepts for terahertz beamforming, polarization control, sensing, and dynamic manipulation. 

Keywords: metasurfaces; metamaterials; frequency-selective surfaces; wavefront engineering; waveplates; flat optics; transmitarrays; reflectarrays

Key collaborators: Functional Materials and Microsystems Research Group, Royal Melbourne Institute of Technology 

A terahertz antenna must be designed around unique requirements in relation to bandwidth, efficiency, directivity, compactness, and fabrication complexity. A major consideration is the broadband operation to capitalise vast bandwidth available in this spectral range. Another factor is the radiation efficiency that is hindered by increasing ohmic loss at terahertz frequencies. We focus on unconventional antenna designs that are crucial for the success of terahertz wireless applications. 

Keywords: all-dielectric antennas; leaky-wave antennas; broadband; high gain; effective medium; gradient index (GRIN) optics; 3D printing; beam steering

Key collaborators:  Tokyo Institute of Technology

A recent paradigm shift in terahertz technology has seen a transition from free-space optics to terahertz integration for practical applications. A challenge lies in high losses of metallic and dielectric materials that prevent a direct adoption of monolithic microwave integrated circuit (MMIC) or photonic integrated circuit (PIC) technologies. Recently, our team has created a unique substrateless platform made of only high-resistivity silicon for broadband low-loss terahertz integrated systems. The main drive of this platform is the effective medium theory that grants access to arbitrary values of permittivity with structural simplicity. Importantly, this great control over material permittivity has led to a wide range of terahertz integrated components with unprecedented performance, i.e., near-to-zero dissipation and a fractional bandwidth exceeding 40%.

Keywords:  terahertz integration; dielectric waveguides; photonic crystals; effective medium; multiplexers; filters

Key collaborators: Information Photonics Group, Osaka University

Terahertz communications is a solution to the spectral congestion at lower microwave and millimetre-wave frequency bands. Tapping into a wider under-utilised bandwidth at terahertz frequencies yields higher channel capacities. In theory, a single terahertz band can support wireless data transfer in the order of Tbit/s with distance reaching several kilometres. While terahertz links cannot replace existing mobile channels owing to line-of-sight propagation, such high-capacity links will become vital for dense base stations in urban areas, last-mile links, data centres, and aircraft-satellite connection for inflight internet services.

Key collaborators: A/Prof Ke Wang, Royal Melbourne Institute of Technology | SmartSat CRC

Terahertz waves are capable of penetrating dry and non-metallic materials such as plastics, papers, clothes, and building materials. Combined with sub-millimetre spatial and depth resolutions, this see-through capability is a key to non-destructive evaluation for quality control, security screening, gesture recognition, and medical diagnosis. Given the unique position of terahertz waves on the spectrum, it is possible to adopt either optical or microwave imaging techniques, depending on requirements and restrictions. Suitable optical techniques include focal plane imaging, optical coherence tomography, digital holography, while microwave techniques include conventional radar and synthetic aperture radar. Great benefits can be derived in diverse industries. We are currently working with different sectors on agriculture, wine, healthcare, and defence for those practical applications.

Key collaborators: School of Agriculture, Food & Wine | Defence Science and Technology Group