Princeton University scientists have significantly minimized the equipment for producing terahertz — an important electromagnetic pulse durable for one millionth of a millionth of a second — to the size of a microchip. The simpler, inexpensive generation of terahertz is likely to have developments in medical imaging, communications, and drug development.
In two articles freshly published in the IEEE Journal of Solid State Circuits, the researchers from Princeton University define one microchip that can produce terahertz waves and a second chip that can capture and read complex details of these waves.
“The system is realized in the same silicon chip technology that powers all recent electronic devices from smart phones to tablets, and therefore costs only a few dollars to make on a large scale,” said chief researcher Kaushik Sengupta, a Princeton assistant professor of electrical engineering.
Terahertz waves are a portion of the electromagnetic spectrum – the extensive class of waves that includes radio, X-rays, and visible light – and stand between the microwave and infrared light wavebands.
The waves have certain unique characteristics that make them fascinating to science.
For one, they pass from one side to another of most non-conducting material, so they might be used to peer through apparel or boxes for security purposes, and since they have less energy than X-rays, they don’t harm human tissue or DNA.
Terahertz waves also collaborate in distinct ways with different chemicals, so they can be used to illustrate specific substances.
Known as spectroscopy, the skill to use light waves to analyze material is one of the most promising – and the most puzzling – applications of terahertz technology, Sengupta said.
To do it, scientists shine a broad range of terahertz waves on an objective and then observe how the waves transform after interacting with it.
The human eye carries out a similar type of spectroscopy with visible light – we see a leaf as green because the light in the green light frequency bounces off the chlorophyll-laden leaf.
The challenging task has been that generating a broad range of terahertz waves and interpreting their interaction with a target involves a complex array of equipment such as bulky terahertz generators or ultrafast lasers.
The equipment’s dimension and expense make the technology impractical for most applications.
Researchers have stayed occupied 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 observing 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 impacts.