Research Clusters

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

Beamforming devices 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 & lens 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; freeform optics

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; modulators

We develop systems that draw from both photonic and microwave domains. leveraging the strengths of each to advance terahertz technologies. Our architectures span heterodyne and homodyne configurations, designed with robustness and rapid responses in mind, and geared toward real-world deployment. A focus is on quadrature homodyne detection as a core strategy for achieving the highest sensitivity in terahertz sensing applications. This research cluster forms a critical bridge between high-performance components and practical applications in sensing and ultra-fast communications, accelerating the path from lab innovation to field-ready solutions. 

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.

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.

The terahertz band hosts a variety of important molecular activities, providing distinct spectral signatures for different materials. These activities include the rotational energy transitions of gas molecules, the low-frequency vibrational modes of complex organic and biological molecules, the collective motions within crystal lattices and hydrogen-bonded networks, and the plasma resonances in semiconductors. We employ advanced spectroscopic techniques to unveil the intrinsic properties of materials within the terahertz band. These efforts are seamlessly integrated with precision metrology, ensuring high-fidelity measurements of spectral response. This combined foundation of spectroscopy and metrology is crucial for accurate material characterisation, advanced sensing applications, and precise diagnostics, particularly where measurement accuracy are paramount.

Terahertz astronomy and atmospheric observation share a common foundation in molecular spectroscopy. Many of the most informative species, water vapour, ozone, carbon monoxide, and complex organics, exhibit their strongest rotational transitions in the terahertz band, making this region indispensable for probing both planetary atmospheres and astrophysical environments. These lines provide precise tracers of chemical abundance, temperature, and dynamical processes, whether used to monitor atmospheric evolution on Earth and other planets or to study energy transport in star‑forming regions and the interstellar medium. Because such signatures are often weak, spectrally crowded, and highly sensitive to instrumental noise, progress in both domains depends on advanced electromagnetic architectures, low‑loss beam‑control structures, and high‑responsivity detectors engineered specifically for the terahertz regime.