Aydin Babakhani wins NSF CAREER Award

Grant supports research into ultrafast terahertz communications, imaging, sensors

Rice University engineer Aydin Babakhani knows how much cellphones and sensors have transformed life in the past two decades, but he’s sure the best is yet to come and plans to make it so with a prestigious CAREER Award he has received from the National Science Foundation (NSF).

CAREER Awards are given to young scientists poised to make a difference.

Babakhani, an assistant professor in Rice University’s Department of Electrical and Computer Engineering, earned the five-year, $500,000 grant for his proposal to develop terahertz chips that send and receive signals at an unprecedented rate and show potential for not only revolutionizing the cellular communication industry but several others as well.

Aydin Babakhani

Terahertz refers to ultrashort waves of electromagnetic energy. These waves occupy the band from about 1 millimeter to 100 micrometers, shorter than microwaves or radar and longer than infrared, ultraviolet and visible light. They don’t pass easily through water or travel long distances, but many nonmetallic materials are transparent to terahertz waves. (Current cellphone signals share space with television and other wireless technologies in the longer – and more crowded — radio frequencies.)

“If we can build sources that generate good power at one terahertz, we can use them for many important applications,” said Babakhani, who joined Rice in 2011. “High-speed communication is probably the most important one.

“The need for data is increasing wireless use, and there’s no other solution than going to higher frequencies,” he said.

Babakhani and his Rice Integrated Systems and Circuits Laboratory proposed the development of small chips that pack a punch. Their chips are both transmitters and receivers, and in the final version should be able to send one-picosecond terahertz pulses. That’s a trillion pulses a second, enough to handle a massive amount of data.

But that’s not all. The lab envisions its inexpensive chip being mounted by the thousands in densely populated areas like downtown Houston. The chips could be plentiful enough to communicate with cellphones and each other via line of sight and will have the ability to steer beams to moving targets.

“We could do those things today with a laser-based system that costs a few hundred thousand dollars, but that obviously won’t fit in your cellphone,” he said. “We want to build the entire communications system on a single chip that potentially costs less than a dollar.”

The Babakhani lab already holds a record for sending the fastest terahertz signals — eight-picosecond pulses — from their chips. “We produce these ultrashort pulses, a few picoseconds, and use amplitude modulation to get a terabit-per-second communication link,” he said.

Having the two-way chips in phones and distributed throughout an urban environment would only account for part of the system, Babakhani said. Fortunately, he’s thinking big-picture. “Once you have chips installed every 100 meters, you have to get the data they handle to and from larger stations,” he said. “You can use fiber optics, but then you’d have a construction project every 100 meters, and that would be a mess.”

Instead, the chips, the equivalent of small towers, would beam data to larger towers through line-of-sight links. “You won’t have to link them with fibers,” he said.

The ability to handle massive data with inexpensive devices leads to other possibilities, including more formidable sensors for vehicles. “Most fatal accidents are due to human error,” Babakhani said. “The potential of this technology is in advanced radar systems for autonomous cars. We see clearly how rapidly that’s growing.

“These accurate radar systems can better detect pedestrians, objects and other cars. When an accident is happening, it can activate automatic braking much faster than humans can react.

“It’s really nice that we are starting to see these things in commercial cars,” said Babakhani, who mentored a Rice student team that won the 2015 Engineering Design Showcase with its design for a dynamic radar and digital imaging system for vehicles. “It’s going to take another five to 10 years to bring the cost of the technology so low that we can have it in every car.”

Babakhani expects terahertz-based imaging will enable things like gaming systems that track a player’s every twitch to ubiquitous screening systems at airports that could eliminate the need for security lines. “If you have these sensors installed everywhere in an airport, they can be on constant lookout for explosives or hidden metallic objects,” he said. “There are a lot of challenges, but this could be a very good solution.”

He predicted terahertz technology will also increase the power of spectroscopy to detect the presence of and identify many gases simultaneously.

Babakhani noted the technology can’t be fully developed without a way to test it, and no such equipment exists. So his lab is inventing that too. “We’re building a laser-based system that’s basically a custom oscilloscope that goes to one terahertz,” he said. “It will be able to characterize these sources and detectors.”

Babakhani’s work is part of a Rice push that got a boost in 2014 from a $1 million W.M. Keck Foundation grant to advance research into the underutilized terahertz region.