by Terahertz (THz) radiation, occupying the gap between microwaves and infrared light in the electromagnetic spectrum, has long been a relatively unexplored region. However, over the past few decades, terahertz technologies have begun to emerge with promising applications across various fields including healthcare, security, material characterization, and more.
What are Terahertz Waves?
Terahertz waves reside between infrared and microwave portions of the electromagnetic spectrum with frequencies ranging from 0.1 to 10 THz and wavelengths between 1mm to 0.03mm. Though difficult to generate and detect, terahertz waves exhibit unique properties that differentiate them from other regions of the spectrum. Non-ionizing radiation in the terahertz range can penetrate materials like plastic, wood, paper and fabric while still being able to differentiate between materials based on their molecular structure and composition. This penetrating yet high-resolution capability has driven research into exploiting terahertz waves for unique applications.
Medical and Healthcare Imaging
Perhaps one of the most promising application areas of terahertz technologies is in medical and healthcare imaging. Terahertz radiation can provide enhanced contrast compared to other imaging modalities when differentiating between diseased and healthy tissue. As THz waves can penetrate thin layers of tissues like skin, they allow for non-invasive imaging without exposing patients or medical professionals to potentially harmful ionizing radiation unlike X-rays.
Initial research has demonstrated terahertz imaging’s ability to detect burn wounds, skin cancer, bacterial and fungal infections. More advanced clinical studies are exploring its potential in early cancer detection by differentiating cancerous from normal tissues, especially for breast, brain and skin cancers. Additionally, terahertz endoscopy is being investigated for minimally invasive imaging of internal organs during surgery without the need for incisions. With continued improvements in terahertz sources and detectors, this technology could transform medical diagnostics and improve disease monitoring.
Security and Defence Applications
Due to terahertz radiation’s material penetration properties combined with its molecular fingerprint detection, it has also gained significant interest from security and defence sectors. Terahertz imaging can uniquely identify concealed weapons, explosives and chemicals under clothing, packaging or other camouflaging materials. This allows for stand-off detection without direct contact, a crucial capability for inspecting large crowds, vehicles and cargo containers efficiently.
THz imaging has already been deployed for airport luggage and postal package screening. Ongoing research explores expanding its use cases such as personnel scanning to detect concealed contraband and threats. Defence agencies are examining terahertz technology’s utility in non-destructive testing of composites, identification of defects in components, and chemical detection for threat identification. As supporting technologies mature further, terahertz sensing promises to greatly enhance security screening capabilities at borders, events and critical infrastructures.
Material Science and non-destructive Testing
The penetration properties of Terahertz Technologies make it extremely valuable for non-destructive testing and evaluation of material properties without harming the sample. THz imaging can identify defects, delamination or foreign inclusion in composites, ceramics, pharmaceuticals and polymers that may not be visible to the naked eye.
By analyzing the terahertz spectra reflected or transmitted by a material, its molecular structure, density and composition can be determined. This allows for identification of artificial materials from genuine articles and detection of counterfeits. Specific properties like hydration levels in grains or degree of cure in coatings and adhesives may also be measured non-invasively. THz spectroscopy enables real-time quality control, process monitoring and industrial inspection for various manufacturing sectors. Emerging applications involve layer thickness measurement, defect analysis in electronics and evaluating material degradation over time.
New THz Sources and Improving Detection
As research into terahertz technologies expands, so do efforts to overcome challenges around efficiently generating and detecting these elusive waves. Traditional THz sources based on photoconductive antennas and nonlinear optical crystals are giving way to novel techniques like quantum cascade lasers, free electron lasers and photonic crystal fibers that offer higher power output across a wider frequency range.
On the detection front as well, sophisticated mechanisms beyond conventional antennas and pyroelectric detectors are being examined to boost sensitivity and speed. Technological advances incorporated in compact table-top terahertz time-domain spectrometers now allow capturing spectra non-destructively with high resolution. Novel nanoscale plasmonic and graphene-based detectors also display immense promise to enable real-time THz imaging for portable devices in the future.
Overall, as core supporting technologies continue progressing, terahertz applications will go beyond proof-of-concept research to real-world deployments across industries in the coming decade. Early commercialization has commenced in specialized fields, while consumer products integrating THz capabilities remain on the horizon. With more widespread use, terahertz sciences have immense potential to revolutionize domains as diverse as healthcare diagnostics, security inspection, industrial quality control and high data transfer wireless communications.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
