Clean room research could revolutionize computers
CLEMSON — Eric Johnson of Clemson University put on a white “clean suit” that covered his body from head to toe, leaving little more than his eyes exposed.
He stepped into a chamber and stood still as jets blasted him with air. Only when every effort had been made to remove the tiniest of particles from his suit did he open the lab door.
Millions of dollars in highly sensitive equipment were at the ready. Johnson and his research group were there to make photonic and optoelectronic devices.
Those devices have already made it possible to scan barcodes and watch Blu-ray movies, but Johnson is working to take the technology a step further.
His research could fundamentally change how computers work, and fellow scholars are taking a keen interest.
Johnson has been named ACC Distinguished Lecturer. As part of the honor, as many as five universities in the Atlantic Coast Conference will invite him and his colleagues to lecture and, hopefully, stimulate collaborations with other researchers.
“I’m excited to go out and tell people what’s going on here at Clemson in terms of photonics and optoelectronics,” Johnson said. “There’s a lot going on here. We’ve got something special, and being able to share that with people is a good thing.”
Some of his most up-to-date information is coming from his research at the Advanced Materials Research Lab in Anderson County.
Johnson and his research group make devices called “optics” by etching microscopic patterns onto silicon and glass wafers, then they shine an ordinary light beam through the optics to make the light do extraordinary things.
When light is transmitted in precisely the right way, it can carry massive amounts of data. If researchers can figure out how to do it on a large scale at a low cost, it could upend how computers have worked for more than half a century.
Computing has largely depended on copper wires laid on silicon microchips to carry electrons. But in the future, a greater share of information could surf on a wave of light. It would mean computers would run faster and use less energy.
Congratulations for Johnson’s ACC honor came from across the conference, including a note from Robert H. Jones, executive vice president for academic affairs and provost at Clemson.
“Being named distinguished lecturer is the highest honor conferred by the ACC Academic Consortium,” Jones said. “This is great news and well-deserved. It’s an honor that shows the impeccable research and scholarship that he brings to Clemson.”
Johnson illustrated how he transforms light by shining a laser through an optic that projected an orange Tiger paw onto the side of a case in his lab.
To understand how he and his research group made the optic, you have to go back to what they do in the clean room.
Researchers start with a wafer. Inside the cleanroom, the wafer is spun, covered with liquid, exposed to ultraviolet light, stenciled, washed in developer and etched with ions. When it’s all done, they have a disk covered in squares that reflect rainbow colors like a CD and appears smooth to the naked eye.
Viewing it through a microscope, though, reveals something entirely different.
“If you were to look at that Tiger paw optic very closely under a microscope, you would see this topography that more or less looks like the Grand Canyon,” Johnson said. “But the dimensions are on the order of a micron or a few microns. As light propagates and moves through that, it forms the image of a Tiger paw.”
The paw is just a demonstration to show how light can be controlled. One of the real-world applications could be in the emerging field of “silicon photonics,” which merges light-based innovations with traditional microchips, Johnson said.
Those innovations could have a big impact on data centers, the computer networks that crunch massive amounts of information and host websites. Adding elements of light-based technology into microchips could lower costs by reducing energy consumption.
Part of what’s unique about Clemson’s work in the field is that researchers are focused on manufacturing. Graduate students get experience in making sophisticated devices on a relatively large scale and go on to work for the likes of Intel and the national labs.
“They get gobbled up quickly when they graduate,” said Johnson, who is the PalmettoNet Endowed Chair in Optoelectronics and professor of electrical and computer engineering.
The ACC Distinguished Lecturer program is in its inaugural year. The honor will be conferred upon a Clemson faculty member once every three years.
Indumathi Raghu Srimathi, a doctoral student, said Johnson is an excellent lecturer. She has taken three of his classes and is a member of his research group.
“He makes sure you understand the material,” she said. “He has a lot of practical applications. It becomes easier to understand.”
Johnson and his group are also working with blue laser diodes. A separate team won a Nobel Prize in Physics in 2014 for inventing the GaN diodes, which now are present in solid state lighting, entertainment and sensing applications.
The Johnson group is trying to use the diodes to improve how the Navy communicates underwater. They are doing the work with the company Lumany as part of the Small Business Technology Transfer program from the Navy.
“One of the problems now is that the blue-green laser sources are large, bulky, not efficient,” Johnson said. “But by leveraging the blue-laser diodes, they can make a much more efficient system, which in the end reduces cost and complexity.”
The criteria emphasized in the selection of distinguished lecturers are scholarly achievements, prospective impact upon students and faculty at hosting institutions, likely opportunity to stimulate cross-university collaborations and the opportunity to showcase intellectual talent.
Anand Gramopadhye, dean of the College of Engineering and Science, said that Johnson’s selection was a richly deserved honor.
“It acknowledges that Eric is among the best of the best in his field,” Gramopadhye said. “We’re fortunate to have him at Clemson, and we’re looking forward to sharing his knowledge with others throughout the ACC in hopes of inspiring collaborations for the common good.”
Johnson said the work that he does is part of a larger package of services offered by Clemson in the area of optics and photonics. The university has made a significant investment in research related to photonics manufacturing, including a “draw tower” to make optical fiber.
“It brings this cluster of people together,” Johnson said. “It’s a very unique asset in the U.S.with a strong focus on manufacturing related technologies.”