The evolution of terahertz imaging modalities is marked by a rich timeline that encompasses continuous-wave digital holography, ptychography, computed tomography, focal-plane imaging, pulse time-domain holography, single-pixel imaging, and near-field techniques. Each of these modalities manifests specific trade-offs between resolution, acquisition speed, and information richness, demanding innovative approaches to optimize their respective capabilities. A newly published comprehensive review article in Opto-Electronic Technology meticulously synthesizes this progression, elucidating the fundamental working principles and practical applications underpinning each imaging technique.

Continuous-wave (CW) terahertz holography has witnessed significant breakthroughs through the marriage of algorithmic sophistication and refined optical configurations, vastly enhancing image resolution, reconstruction stability, and fidelity. This modality benefits from steady-state terahertz sources and phase-sensitive detection, allowing for precise amplitude and phase retrieval. The advances have paved the way for high-quality, real-time imaging, crucial for applications requiring stringent spatial resolution and dynamic response.

In parallel, terahertz ptychography has expanded its illumination strategies beyond traditional plane waves to include spherical wavefronts and customized beam probes. Coupled with powerful iterative reconstruction algorithms, these developments have enabled phase retrieval with high spatial resolution and expansive fields of view, operational in both transmission and reflection geometries. Such advances significantly enhance imaging throughput and enable detailed phase and amplitude mapping critical for material science and biomedical investigations.

Terahertz computed tomography (CT) has also transcended conventional resolution barriers by employing novel optical elements such as super-oscillatory lenses for lateral resolution and Bessel beams to boost axial resolving power. Moreover, advanced scanning methods involving sparse-angle reconstruction and two-dimensional galvanometer-based beam steering have accelerated volumetric imaging speed, enhancing the practicality of terahertz CT for industrial inspections and biological tissue visualization.

Focal-plane terahertz imaging has overcome its initial limitations related to signal-to-noise ratios through dynamic subtraction, differential detection techniques, and quasi-near-field enhancements. These refinements empower real-time wavefront characterization, verification of metasurface functionalities, and sophisticated polarization- and spectrally-resolved imaging of chemical and biological specimens. These imaging capabilities are particularly transformative in the rapid screening and non-destructive evaluation of materials.

Pulse time-domain holography leverages the broadband coherent detection attributes of ultrafast terahertz pulses, unlocking unique possibilities in material parameter extraction and the examination of complex structured beam propagation dynamics. Its ability to resolve temporal and spectral signatures makes it an indispensable modality for probing transient phenomena and intricate biological and chemical systems.

Single-pixel terahertz imaging marries spatial light modulation with computational algorithms, utilizing optically controlled materials like silicon, vanadium dioxide, and graphene for high-speed pattern encoding. This modality excels in dynamic real-time imaging, near-field super-resolution, and integration with spectral and time-of-flight imaging schemes, expanding the functional versatility of terahertz imaging in both scientific and industrial contexts.

Near-field terahertz microscopy presents three principal approaches: aperture-type, photoconductive probe, and scattering-type techniques. These methods have facilitated extraordinary breakthroughs such as mapping carrier distributions in two-dimensional materials, visualizing surface plasmon polaritons, characterizing dielectric contrasts in phase-change media, and conducting biomedical imaging with spatial resolution down to tens of nanometers. This spatial precision heralds new vistas in the study of nanoscale phenomena.

The inherent properties of terahertz radiation — non-ionizing nature, heightened sensitivity, and the capacity to reveal distinct spectral fingerprints — have firmly established terahertz imaging as a cutting-edge tool with distinctive advantages in security screening, biomedical diagnostics, and industrial non-destructive testing. Despite these advancements, technical challenges remain, especially concerning further resolution enhancement, faster image acquisition, and seamless system integration.

Future progress in terahertz imaging is poised to benefit exponentially from the synergistic integration of emerging deep learning algorithms, innovative hardware designs, and multimodal imaging approaches. These developments aim to deliver real-time, high-precision, and portable systems capable of broad deployment across diverse real-world applications. The promise is a transformative leap in how materials and biological tissues are inspected, characterized, and understood.

Leading research groups have been instrumental in pushing these frontiers forward. Prof. Lu Rong’s team focuses on optical information processing, digital holography, and biomedical imaging. Prof. Nikolay Petrov’s lab explores holography and femtosecond optics with terahertz applications. Prof. Xinke Wang investigates terahertz metamaterials and transient material processes. Prof. Liguo Zhu advances terahertz photonics and computational imaging. Prof. Min Hu concentrates on the development of terahertz sources and applications, while Prof. Yan Zhang’s research spans photonic crystal devices and surface plasmonic optics.

The comprehensive review published in Opto-Electronic Technology offers an authoritative and timely synthesis of the field’s advancements, serving as a crucial reference point for researchers, engineers, and end-users aiming to harness terahertz imaging’s full potential. As the technology matures, it stands on the cusp of revolutionizing industries ranging from security and healthcare to manufacturing quality control, revolutionizing how invisible wavebands are harnessed to reveal the hidden universe of materials and living tissues.

Subject of Research: Terahertz imaging technology and its applications
Article Title: Terahertz imaging technology: progress and applications
News Publication Date: 2026
Web References: Opto-Electronic Technology Archive
References: Tian Y Y, Chen X Y, Zhang Z C et al. Terahertz imaging technology: progress and applications. Opto-Electron Technol 2, 250009 (2026). DOI: 10.29026/oet.2026.250009
Image Credits: Opto-Electronic Technology (OET)
Keywords: Terahertz, imaging, continuous-wave, focal-plane, time-domain holography, single-pixel, near-field

Terahertz waves occupy a unique position on the electromagnetic spectrum, nestled between microwaves and infrared light. Their non-ionising nature means they avoid the harmful radiation risks commonly associated with X-rays, positioning them as an ideal candidate for safe medical diagnostics. Furthermore, terahertz radiation exhibits exceptional sensitivity to water content variations in biological tissues, a characteristic that enables precise differentiation between healthy and pathological tissues. Despite these advantages, the practical deployment of terahertz imaging has been hampered by the bulkiness and slow acquisition speeds of existing systems.

The Warwick team’s innovation addresses these challenges by engineering a compact, fibre-optic-based platform that significantly streamlines the imaging process. The fibre coupling introduces a new level of flexibility and miniaturization; it permits the THz system to be either handheld or integrated into robotic surgical instruments without compromising performance. This compactness is crucial for clinical settings where mobility and ease of use are paramount, and cumbersome apparatuses have previously impeded broader adoption.

Achieving near video-rate image acquisition represents a transformative shift for terahertz imaging technology. The system developed by the University of Warwick operates at speeds more than five times faster than the current state-of-the-art devices. Operating at approximately 360 micrometers spatial resolution, the system captures detailed images rapidly enough to be considered real-time for many clinical applications. This advancement not only enhances the efficiency of diagnostics but also positions terahertz imaging as a competitive adjunct or alternative to existing optical and radiological imaging techniques.

Proof-of-concept trials underscore the practical utility of this new technology. Using animal tissue samples, the team demonstrated the system’s ability to differentiate between various biological components, such as fat and protein within porcine tissue. More compelling still, the system was employed in vivo to capture dynamic images of a wound on a human volunteer’s arm in real time. These demonstrations highlight the system’s sensitivity to subtle biological differences and its readiness for translation from bench to bedside.

Professor Emma MacPherson, a leading physicist at Warwick’s Department of Physics, emphasizes the clinical implications of this breakthrough. She notes that the combination of speed, resolution, and portability engenders a new class of terahertz imaging devices that clinicians can deploy directly. The handheld or robotic-integrated devices could enable faster diagnostic decisions, reduce the need for invasive biopsies, and allow continuous monitoring of wound healing and skin lesions without exposing patients to ionizing radiation.

Terahertz imaging provides a compelling middle ground between traditional imaging techniques. While modalities like MRI or CT scans provide remarkable detail, they are often costly, immobile, and time-consuming. Conversely, optical methods like dermoscopy or ultrasound are more portable but offer limited tissue contrast and depth specificity. The University of Warwick’s compact, fibre-coupled THz imaging platform bridges this gap, offering a balance of resolution, speed, and for the first time, practical accessibility.

Technical innovation lies at the heart of this achievement. Integrating single-pixel imaging within a fully fibre-coupled architecture mitigated the bulk and complexity of traditional systems. Single-pixel imaging, which reconstructs images from structured illumination and subsequent computational algorithms rather than from large multi-pixel detector arrays, synergizes well with fibre coupling technology. This combination reduces hardware demands while preserving spatial resolution and imaging speed, enabling the sleek form factors feasible for clinical use.

The implications extend beyond diagnostic dermatology and wound assessment. Given terahertz waves’ sensitivity to molecular composition and hydration states, this technology holds promise for early cancer detection, intraoperative margin assessment in tissue excisions, and potentially monitoring the efficacy of treatments. Integrating the system within robotic surgical platforms could provide surgeons with unparalleled real-time feedback, significantly enhancing precision and patient outcomes.

Supporting the research, funding from the Engineering and Physical Sciences Research Council (EPSRC) facilitated the experimental studies necessary to refine system design and validate its biomedical applications. Published in the prestigious journal Nature Communications, the study details comprehensive experimental validations, corroborating the system’s robustness across diverse biological tissues and highlighting avenues for future clinical trials.

This breakthrough in terahertz imaging represents a pivotal moment in medical diagnostics technology, combining fundamental physics with cutting-edge engineering to overcome long-standing barriers. By offering rapid, non-ionising, high-resolution images through a versatile, compact device, the University of Warwick’s innovation promises to shift terahertz imaging from a niche research tool to an integral component of everyday clinical practice. Patients stand to benefit from faster, safer diagnoses while practitioners gain new capabilities for precise, real-time tissue characterization.

Subject of Research: Animal tissue samples
Article Title: All-fibre-coupled terahertz single-pixel imaging for biomedical applications
News Publication Date: 12-Jan-2026
Web References: http://dx.doi.org/10.1038/s41467-026-68290-x
References: MacPherson, E. et al., “All-fibre-coupled terahertz single-pixel imaging for biomedical applications,” Nature Communications, 2026. DOI: 10.1038/s41467-026-68290-x
Keywords: Terahertz imaging, biomedical diagnostics, fibre-coupled system, single-pixel imaging, non-ionising radiation, real-time imaging, medical imaging technology, high-resolution imaging, photonics, applied physics

Terahertz radiation, occupying the electromagnetic spectrum between infrared and microwave frequencies, has long captivated researchers due to its potential in applications ranging from high-resolution imaging to wireless communications. However, controlling and guiding terahertz waves with precision has remained a formidable challenge, often hindered by material constraints and diffraction limits. The emergence of plasmon polaritons—quasiparticles arising from the coupling of electromagnetic waves with collective electron oscillations at material interfaces—offers a tantalizing path towards overcoming these obstacles by confining and manipulating electromagnetic energy at scales below the diffraction limit.

In this context, topological insulators have emerged as a fertile ground for achieving exotic electromagnetic phenomena. These materials, characterized by insulating bulk states and conductive surface states protected by topological order, present unique avenues for plasmonic excitations. The study, conducted by Viti, Schiattarella, Sichert, and colleagues, expertly exploits these surface states to realize terahertz plasmon polaritons with an adjustable dispersion relationship—a critical parameter dictating how these quasiparticles propagate and interact.

The research centers on engineered metaelements constructed from topological insulator materials. By carefully designing the geometric and electrostatic parameters of these metaelements, the team achieved a tunable dispersion profile, allowing precise control over the phase velocity and confinement of terahertz plasmon polaritons. This level of tunability is significant because it enables the tailoring of plasmonic responses for specific application requirements, ranging from sensing and modulation to on-chip photonic circuitry.

Central to their methodology was the integration of advanced nanofabrication techniques with sophisticated terahertz spectroscopy measurements. The researchers employed near-field terahertz microscopy to visualize the propagation of plasmon polaritons across the topological insulator surface with nanoscale spatial resolution. These spatially resolved measurements not only confirmed the existence of tunable plasmonic modes but also allowed direct access to their dispersion characteristics, providing a firm experimental grounding to the theoretical models proposed.

The interplay between topological protection and plasmonic behavior represents a novel frontier harnessed by the team. The inherent robustness of surface states in topological insulators against scattering and defects imparts remarkable stability to the plasmon polaritons, ensuring low-loss propagation even in imperfect material conditions. This resilience is a pivotal advantage when designing practical devices that require stable, high-quality plasmonic signals.

Importantly, the tunability introduced in these metaelements is achieved “by design,” meaning that the dispersion properties can be predetermined through precise structural engineering rather than by post-fabrication adjustments or external stimuli alone. This represents a paradigm shift in plasmonics, where static material properties typically dictate electromagnetic responses. The work signals a move towards programmable photonic materials that can be optimized at the design phase for bespoke terahertz functionalities.

The potential applications of this research stretch across various high-impact domains. In telecommunications, for example, tunable terahertz plasmon polaritons could enable ultra-fast, miniaturized modulators and filters that enhance signal processing capabilities. Similarly, in spectroscopic sensing, these devices could achieve heightened sensitivity and selectivity by exploiting tailored dispersion to maximize light-matter interactions with target analytes.

Moreover, the findings complement and advance ongoing efforts to integrate topological photonic structures with metamaterials—artificial composites engineered to exhibit properties not found in nature. By combining the topological nature of surface states with the versatility of metamaterial design, the study opens avenues for producing reconfigurable, multifunctional optical platforms operating at terahertz frequencies.

The study also shines a light on the rich physics governing plasmon polaritons in nontrivial topological landscapes. The observed dispersion tuning can be theoretically understood through modifications in the electronic band structure and electromagnetic boundary conditions imposed by the engineered metaelements. These insights enrich the conceptual framework of plasmonics, suggesting new physics to explore in other correlated electron systems and two-dimensional materials.

As research in terahertz science accelerates, this work underscores the importance of marrying topological effects with plasmonics to surmount lingering technological challenges. The use of topological insulator metaelements with built-in tunability paves the way toward scalable, practical terahertz components that maintain performance while reducing complexity and energy consumption.

Looking ahead, the authors suggest exploring dynamic tuning mechanisms, such as electrical gating or optical pumping, to complement the design-based tunability and introduce real-time control over plasmon polariton dispersion. Such developments would significantly broaden the functional repertoire of terahertz plasmonic devices, enabling adaptive systems capable of responding to environmental changes or user-defined signals.

Additionally, expanding this platform to hybrid systems combining topological insulators with other two-dimensional materials, like graphene, could yield synergistic benefits by leveraging their complementary electronic and optical properties. This could lead to multi-band operation and enhanced nonlinear effects critical for advanced photonic applications.

In conclusion, this pioneering study by Viti and colleagues represents a remarkable stride in nanophotonics and topological materials science. By tracing and tuning terahertz plasmon polaritons through custom-designed topological insulator metaelements, they demonstrate profound control over electromagnetic waves at nanoscales. This fusion of theory, materials science, and cutting-edge experimental techniques heralds a new era in terahertz technology, promising transformative impacts across scientific research and industry.

The meticulous integration of topological concepts with plasmonics evidenced here not only expands the fundamental understanding of light-matter interaction but also catalyzes the ongoing evolution of next-generation photonic devices. As efforts continue to harness these phenomena, the vision of compact, efficient, and tunable terahertz platforms for communication, sensing, and quantum technologies moves steadily into reality.

Such advancements epitomize the power of interdisciplinary research, where physics, materials engineering, and optical science converge to unlock unprecedented technological capabilities. The tunable dispersions engineered within these metaelements stand as a testament to human ingenuity in manipulating the quantum and classical realms of light.

This work is set to inspire a new wave of experimental and theoretical inquiry aimed at exploring and expanding the boundaries of topological plasmonics. The implications for future research are vast, including the exploration of dissipative and nonlinear effects, the impact of external field perturbations, and the integration of such systems into complex optoelectronic architectures.

Ultimately, this research not only enriches the scientific landscape but also lays a solid foundation for real-world innovations that will shape communications, sensing, and computation technologies in the coming decades, reinforcing the pivotal role of terahertz science in the technological frontier.

Subject of Research: Terahertz plasmon polaritons with tunable dispersion in topological insulator metaelements

Article Title: Tracing terahertz plasmon polaritons with a tunable-by-design dispersion in topological insulator metaelements

Article References:
Viti, L., Schiattarella, C., Sichert, L. et al. Tracing terahertz plasmon polaritons with a tunable-by-design dispersion in topological insulator metaelements. Light Sci Appl 14, 288 (2025). https://doi.org/10.1038/s41377-025-01884-0

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41377-025-01884-0