Ahmed Tewfik

UT researchers have built a nonlinear mirror that can detect harmful gases unseen to the naked eye. 

Photo Credit: Erik E. Zumalt | Daily Texan Staff

Cockrell School of Engineering researchers have designed and built a "nonlinear mirror" that could improve laser technology in fields such as chemical detection and biomedical research.

“The significance of the work is that it will, in the long term, make it possible to build very small optical devices, including laser sources,” said Ahmed Tewfik, electrical and computer engineering department chair. “This, in turn, will enable the deployment of well-understood and useful optical innovations into a host of new application areas, including medical applications, scientific instruments and defense.”

The nearly yearlong research study was led by engineering professors Andrea Alu and Mikhail Belkin along with engineering graduate students. The Technical University of Munich also worked on the study with the UT researchers.

Unlike traditional nonlinear crystals, the nonlinear mirror is made up of materials that are not found in nature, called metamaterials, and can be specifically designed to have uncommon optical properties, according to Belkin. 

The research team built a 400-nanometer thick mirror that doubles the frequency of the light that is shone at it by using light input intensity as small as that of a laser pointer. The nonlinear materials produce light intensities that are 1 million times more intense than those of natural materials, which helps researchers sense chemicals that they were not able to before.

“The beauty of our design is that unlike traditional nonlinear optical crystals which are limited by what nature gives you, we can play with the thickness and engineer this material to produce extremely large nonlinear optical response and to work at various wavelengths,” Belkin said.

Their research is groundbreaking in what it has shown about the use of engineered materials in extremely small laser designs, Alu said.

“This work opens a new paradigm in nonlinear optics by exploiting the unique combination of exotic wave interaction in metamaterials and of quantum engineering in semiconductors,” Alu said.

Along with possible biomedical applications, the mirror helps sense dangerous chemicals and gases that are not visible to the naked eye. This sensing is done in the mid-infrared spectral range, according to Belkin.

“If you are able to see in the mid-infrared range, then all the dangerous gases will have very specific colors, and so if you have a laser source with very specific wavelengths, you can use it to detect the presence of gas in the air,” Belkin said. “The nonlinear mirror can help us to generate these specific wavelengths.”

The metamaterials were grown with the help of collaborators at the Walter Schottky Institute of the Technical University of Munich, but much of the research and work that went into designing, building and testing the nonlinear mirror took place at the electrical and computer engineering department at UT as well as the Pickle Research Center, according to Tewfik.

According to Belkin, though this invention is a big step forward for nonlinear technology, there is still a lot of work to be done and many improvements still to be made.

A few days ago engineering professor Bob Metcalfe traveled to Tokyo, Japan to receive the C&C award for his contributions to the development of the Internet from the NEC C&C Foundation.

Metcalfe is known for the contributions he made while working with 3Com, a multibillion dollar networking company that was acquired by computer giant Hewlett-Packard in 2010. Metcalfe worked with the company in the 1980s to develop Ethernet local-area networking products based on the UNIX operating system and TCP/IP network technologies.

He accepted the award and split the about $130,000 prize with his technological partner Norman Abramson, a professor emeritus at the University of Hawaii.

UT hired Metcalfe to teach engineering and entrepreneurship in Jan. 2011. Metcalfe said Ethernet originally developed from Abramson’s radio-based Aloha Network in the 1970s, which was the first demonstration of wireless packet data networks.

Metcalfe said he never expected the Internet would become so popular.

“David [Boggs] and I built the first Ethernet as a tool for a lab to access a high speed, high quality printer,” Metcalfe said. “We were the first printer to access a building full of personal computers. Turns out, when you connect things you make them more valuable.”

Metcalfe said the Internet has disrupted industries like journalism, telephone and television, but the latest surprise in the Internet world has been Facebook. He said he predicted the next big changes would probably include energy, health care and education.

“We need to solve energy urgently,” Metcalfe said. “The cost of energy, the fact that it’s owned by people who want to kill us and the fact that it’s polluting the atmosphere.”

He said the development of new energy technology could take as long as it took to build the Internet.

Metcalfe said the greatest problem he sees with Internet today is network security and there needs to be a way to improve a network’s defenses.

Ahmed Tewfik, electrical and computer engineering department chair, said he was not surprised Metcalfe got the award because he is known on an international level. Tewfik was one of the professors in the Cockrell School of Engineering who recruited Metcalfe last fall.

Tewfik said he was in graduate school when Metcalfe worked on the Ethernet, and in meeting him, Tewfik met a personal hero. He also said Metcalfe was not the typical university professor because he was outspoken and had a unique way of approaching things.

“I think he will have a great influence on changing the culture at UT to one that’s more like MIT, which is more entrepreneurial in nature,” Tewfik said. “When he came in he and I talked about making a startup entrepreneur course, and it’s now a two-semester class.”

The course is called the 1 Semester Startup Course and provides mentoring from Austin entrepreneurs to students with a startup idea for a company and the chance to develop the company over a semester. After this semester, the course will last for two semesters. The class held their first “Demo Show” Thursday night, in which students presented company pitches to Austin entrepreneurs.

Biomedical engineering senior Mariel Bolhouse is in Metcalfe’s class and presented Magis Isotopes, a company that works to improve the efficiency of nuclear fuel by isotope separation.

Bolhouse said she has enjoyed the experience of having someone of that prestige be accessible and willing to give advice.

“He’s taught me about the status quo,” Bolhouse said. “My company is going on hold and at first I came up with a pitch that was going to be all sunshine and roses. He taught me it was important to be up front if I didn’t have the answer to a problem.“