Ruonan Han looks for to press the limitations of electronic circuits.
Ruonan Hans research is driving up the speeds of microelectronic circuits to allow new applications in communications, picking up, and security.
Han, an associate teacher who recently earned tenured in MITs Department of Electrical Engineering and Computer Science, focuses on producing semiconductors that operate efficiently at very high frequencies in an effort to bridge what is referred to as the “terahertz gap.”
The terahertz region of the electromagnetic spectrum, which lies between microwaves and infrared light, has mostly eluded scientists since traditional electronic devices are too sluggish to manipulate terahertz waves.
Ruonan Han, associate teacher in the Department of Electrical Engineering and Computer Science, looks for to press the limits of electronic devices so they can run effectively at terahertz frequencies. Credit: M. Scott Brauer
” Traditionally, terahertz has actually been unexplored area for scientists just because, frequency-wise, it is too expensive for the electronic devices people and too low for the photonics individuals,” he says. “We have a lot of limitations in the products and speeds of gadgets that can reach those frequencies, once you arrive, a lot of amazing things happen.”
Terahertz frequency waves can move through solid surface areas and produce very precise, high-resolution images of what is within, Han says.
Radio frequency (RF) waves can take a trip through surfaces, too– thats the factor your Wi-Fi router can be in a different room than your computer. But terahertz waves are much smaller sized than radio waves, so the gadgets that transfer and receive them can be smaller sized, too.
Hans team, in addition to his partner Anantha Chandrakasan, dean of the School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science, recently demonstrated a terahertz frequency identification (TFID) tag that was barely 1 square millimeter in size.
” It doesnt require to have any external antennas, so it is essentially just a piece of silicon that is super-cheap, super-small, and can still deliver the functions that a regular RFID tag can do. Due to the fact that it is so small, you could now tag basically any product you want and track logistics information such as the history of manufacturing, and so on. We could not do this before, however now it becomes a possibility,” he says.
Tuning in
A basic radio motivated Han to pursue engineering.
As a kid in Inner Mongolia, a province that stretches along Chinas northern border, he pored over books filled with circuit schematics and diy suggestions for making printed circuit boards. The primary school trainee then taught himself to develop a radio.
” I could not invest a lot into those electronic parts or invest excessive time tinkering with them, however that was where the seed was planted,” he says. “I didnt understand all the information of how it worked, but when I turned it on and saw all the parts collaborating it was truly fantastic.”
Han is thankful hes at MIT, where the trainees arent afraid to handle seemingly intractable issues and he can work together with colleagues who are doing extraordinary research study in their domains. Credit: M. Scott Brauer
Han studied microelectronics at Fudan University in Shanghai, concentrating on semiconductor physics, circuit style, and microfabrication.
Fast advances from Silicon Valley tech business influenced Han to register in a U.S. graduate school. While making his masters degree at the University of Florida, he worked in the laboratory of Kenneth O, a pioneer of the terahertz incorporated circuits that now drive Hans research study.
” Back then, terahertz was thought about to be expensive for silicon chips, so a great deal of people thought it was a crazy idea. Not me. I felt truly fortunate to be able to deal with him,” Han states.
He continued this research study as a PhD trainee at Cornell University, where he sharpened ingenious methods to supercharge the power that silicon chips can produce in the terahertz domain.
” With my Cornell advisor, Ehsan Afshari, we explore different types of silicon chips and innovated numerous mathematics and physics hacks to make them perform at very high frequencies,” he says.
As the chips became smaller and quicker, Han pushed them to their limits.
Making terahertz available
Han brought that innovative spirit to MIT when he joined the EECS faculty as an assistant teacher in 2014. He was still pushing the efficiency limitations of silicon chips, now with an eye on useful applications.
“Our goal is not only to deal with the electronic devices, however to explore the applications that these electronics can make it possible for, and show the expediency of those applications. One specifically crucial element of my research study is that we do not just wish to handle the terahertz spectrum, we desire to make it accessible. We do not want this to simply happen inside labs, but to be utilized by everyone. So, you need to have very low-priced, really trustworthy components to be able to deliver those sort of abilities,” he says.
Han is studying making use of the terahertz band for rapid, high-volume data transfer that could push wireless devices beyond 5G. The terahertz band might be useful for wired communications, too. Han just recently demonstrated the use of ultrathin cable televisions to transmit information in between 2 points at a speed of 100 gigabits per second.
Terahertz waves also have unique residential or commercial properties beyond their applications in communications devices. The waves cause various molecules to turn at distinct speeds, so scientists can use terahertz devices to expose the structure of a substance.
“We can in fact make affordable silicon chips that can odor a gas. Weve produced a spectrometer that can at the same time recognize a big variety of gas molecules with really low false alarms and high sensitivity. This is something that the other spectrum is not great at,” he says.
Hans group made use of this work to create a molecular clock that turns the molecular rotation rate into a highly stable electrical timing signal for navigation, communication, and picking up systems. Although it operates much like an atomic clock, this silicon chip has a simpler structure and greatly minimized cost and size.
Running in mainly unexplored locations makes this work specifically challenging, Han states. Despite decades of advances, semiconductor electronics still arent fast enough, so Han and his trainees must continuously innovate to reach the level of performance needed for terahertz gadgets.
The work also requires an interdisciplinary frame of mind. Teaming up with colleagues in other domains, such as chemistry and physics, makes it possible for Han to check out how the innovation can cause helpful brand-new applications.
Han is happy hes at MIT, where the students arent scared to handle relatively intractable problems and he can team up with coworkers who are doing amazing research study in their domains.
“Every day we are believing and dealing with new problems about ideas that other people, even people who work in this field, may think about super-crazy. And this field remains in its infancy today. There are a great deal of new emerging parts and products, and prospective applications and new needs keep popping up. This is just the beginning. There are going to be really big opportunities lying ahead of us,” he states.
” Back then, terahertz was considered to be too high for silicon chips, so a lot of individuals believed it was a crazy concept. I felt truly fortunate to be able to work with him,” Han states.
One particularly essential aspect of my research study is that we dont simply desire to deal with the terahertz spectrum, we desire to make it available. Han is studying the use of the terahertz band for quick, high-volume information transfer that might press cordless gadgets beyond 5G. Han recently demonstrated the usage of ultrathin cable televisions to transmit data in between 2 points at a speed of 100 gigabits per second.
