Terahertz chips a new way of seeing through matter

Terahertz chips a new way of seeing through matter






Terahertz chips a new way of seeing through matter
Terahertz chips a new way of seeing through matter

New Delhi: Moving from a tabletop setup with lasers and mirrors to a pair of microchips small enough to fit on a fingertip, researchers led by a scientist of Indian origin have drastically shrunk the terahertz wave equipment which may hold the key to advances in medical imaging, communications and drug development Electromagnetic pulses lasting one millionth of a millionth of a second called terahertz waves have long required elaborate and expensive equipment to use and hence was unwieldy.
In two articles recently published in the IEEE Journal of Solid State Circuits, the researchers from Princeton University describe one microchip that can generate terahertz waves, and a second chip that can capture and read intricate details of these waves.
"The system is realized in the same silicon chip technology that powers all modern electronic devices from smart phones to tablets, and therefore costs only a few dollars to make on a large scale" said lead researcher Kaushik Sengupta, a Princeton assistant professor of electrical engineering.
Terahertz waves are part of the electromagnetic spectrum - the broad class of waves that includes radio, X-rays and visible light - and sit between the microwave and infrared light wavebands.
The waves have some unique characteristics that make them interesting to science.
For one, they pass through most non-conducting material, so they could be used to peer through clothing or boxes for security purposes, and because they have less energy than X-rays, they don't damage human tissue or DNA.
Terahertz waves also interact in distinct ways with different chemicals, so they can be used to characterize specific substances.
Known as spectroscopy, the ability to use light waves to analyze material is one of the most promising - and the most challenging - applications of terahertz technology, Sengupta said.
To do it, scientists shine a broad range of terahertz waves on a target then observe how the waves change after interacting with it.
The human eye performs a similar type of spectroscopy with visible light - we see a leaf as green because light in the green light frequency bounces off the chlorophyll-laden leaf.
The challenge has been that generating a broad range of terahertz waves and interpreting their interaction with a target requires a complex array of equipment such as bulky terahertz generators or ultrafast lasers.
The equipment's size and expense make the technology impractical for most applications.
Researchers have been working for years to simplify these systems.
"Instead of directly reading the waves, we are interpreting the patterns created by the waves," Sengupta said.
"It is somewhat like looking for a pattern of raindrops by the ripples they make in a pond.
" Daniel Mittleman, a professor of engineering at Brown University, said the development was a very innovative piece of work, and it potentially has a lot of impact.

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