Terahertz rays may be invisible to the human eye, but University research on these waves is spotlighting their possible uses, ranging from deciphering water content in a bodily tissue to detecting concealed weapons on a person to quality control in manufacturing.
T-rays, as they are called, are not as ubiquitous as other energies on the electromagnetic spectrum, like ultraviolet waves, which are used in barcodes, medical light therapy, DNA sequencing and other applications. However, a detector developed by Engineering Prof. Jay Guo and his research lab could allow T-rays to become more of a household necessity.
T-rays fall on the electromagnetic spectrum below infrared waves — energy that’s harnessed in things like remote controls and heat lamps that warm food — and visible light, which humans can see. They have shorter wavelengths and are of a higher energy than microwaves and radio waves.
Though T-rays have been difficult for engineers to study and to develop technologies around, Guo said their uses are quite varied.
“It is a scientifically rich frequency band and offers unique value for imaging, chemical identification and characterization of materials,” Guo wrote in an email.
Current T-ray detectors are difficult to work with because they are too cumbersome, need especially cold temperatures or are unable to work in real time. Guos' transducer – a technology which, in essence, transforms one form of energy to another – eases this process by allowing for T-ray conversion into sound waves.
The transducer is composed of plastic and carbon nanotubes. When T-rays reach the device, they are absorbed by the nanotubes and turned into heat energy. This energy is passed onto the plastic, which is called polydimethylsiloxane, PDMS for short. The PDMS expands and makes an ultrasound wave.
Researchers developed an ultrasound detector, a tiny plastic ring that is only a few millimeters wide. This detector has a response time of a fraction of a millionth of a second. Guo said this allows for real-time terahertz imaging most of the time.
“The low photon energy of terahertz radiation is biologically safe,” Guo wrote. “Therefore developing small and easy-to-operate terahertz components, including sources, waveguides, and detectors, would benefit both fundamental research and applications.”
While the team’s work is currently devoted to the development of a compact, sensitive and fast T-ray detector capable of operating in room temperature, Guo hopes they will be able to improve the sensitivity. Improved sensitivity can show video-rate imaging, opening doors for more uses and opportunities with T-rays.