Nano Focused

Physics professor weighs in on tiny materials.

Nano Focused

The field of nano-optics is unfamiliar to many, due in part to its complexity — and a simple matter of scale.

The structures and materials used in the lab of Baylor’s Dr. Howard Lee, an assistant professor of physics in the College of Arts and Sciences, are invisible to the human eye — “10,000 times smaller than our hair.”

While the materials may be miniscule, applied uses for Lee’s research are vast, with high demand for efficient materials and processes across all sectors of science and industry. The demand is what drew Lee into the study of material science and physics.

“We have display screens, optical fiber for communication, lenses, et cetera,” Lee said. “Many of them have been developed and improved for a long time, but the only thing you can really change is the material used. In order to find new applications and new devices, you actually need to find some new material. That is the key.”

Lee’s work in nano-optical structures and metamaterials is remarkable, moving into a microscopic level of focus that measures down to the two-dimensional level. 

“It’s only a few tens of an atom thick, like a 2-D surface. But more important for me is how we link this material property to the optical property. This is something we have been working on quite a lot.”

For Lee and other researchers at the intersection of nano-optics and metamaterials, the pursuit of advancements and new discoveries in the field run in a parallel — to change the behavior of the optical properties requires development of new materials that are able to control them.

Nano-optical structures help to guide light in very small volume with very high speed, close to the speed of light. This allows production of a new generation of optical computers and technologies. In addition, recent advancement of metasurfaces facilitates the production of ultrathin lenses, polarizers, filters and similar crucial components. These optics allow for smaller and more efficient imaging systems with medical and commercial applications, or even for enhanced video displays, virtual reality and augmented reality technologies. Breakthroughs with nano-optical structures and metasurfaces using optical fibers looks to create better optical fiber communication systems and imaging technologies.

“They’re really in parallel,” Lee said. “You’re doing the optical development, but at the same time, you need to have the material science to support, to get a new innovation and new physics from that. If we have better, new material, you can have a better optical property and new fundamental physics.”

Once the new material — so called “zero refractive index materials” — are grown and developed, the focus shifts to improving the function of the optical physics and light-matter interaction on the nanometer scale. The goal is maximum interaction and efficiency.

With interest from all sectors of industry and science, Lee’s approach considers material science advancement, optical improvements and energy efficiency.

“How can we make it much lower loss? The loss is important for application, but how can we reduce losses on that? At the same time, how can we make it more efficient? For instance, instead of needing 50 volts for active tuning of the material, maybe we can just apply one volt to control the device. This needs to be understood on the material point of view.”

Lee’s work has garnered the attention of his peers in the scientific research community, as well as industry leaders in the fields of physics. 

In 2018, Lee was awarded a $500,000 CAREER Award from the National Science Foundation (NSF) for developing the ultra-thin, nanoscale optical films with electrically tunable properties. 

The CAREER Award is a highlight among many prestigious honors for Lee. He also was selected for the 2017 Defense Advanced Research Projects Agency (DARPA) Young Faculty Award and was named in February 2020 as one of 13 SPIE Rising Researchers by the International Society for Optics and Photonics (SPIE).

In a field that trades in the currency of ideas and theories that often go untested or unrecognized, these grants and awards can be the encouragement a researcher needs in what can be an ultra competitive pursuit of science and grant funding.

“If you get an award like this, it will help when applying for other grants since it shows that you are established and have formed the research foundation/capability. It helps to continue getting research funding to keep the work going,” Lee said. “In the U.S., funding is a challenge we’re always seeking to overcome in research. We only have 10 percent success rates, for example. So, it’s great to have something get accepted and to be told the idea you’re doing could be useful for the program manager.”

A major component of Baylor’s endeavor for R1 status is to improve the research facilities and laboratories available to faculty to produce many of the kinds of breakthroughs that Lee and his nano-optics lab have been able to accomplish.

One of the priority facilities is a cleanroom with fabrication capability— a completely controlled and sterile environment that allows for optimal production of Lee’s metamaterials.

“When you’re making materials that are so small and thin and high quality, you don’t want to have any impurities, like dust, on your sample. That’s what this cleanroom environment is able to do, limiting dust particles in the space. That means when you take out the sample, you’ll not contaminate it,” Lee said.

“The bigger issue is, if you have all of the capabilities you need to grow the materials for nanofabrication, then basically you can make all of the material that would be useful not only for material science, but also for optics, for electronics and for mechanical science.”

The cleanroom, coupled with the e-beam lithography machine and other equipment in Lee’s lab, will put Baylor among the best labs in the country.

“The cleanroom is a great start, but we hope to move forward with more equipment inside the room as well,” Lee said.

Advancements like the cleanroom will be a cornerstone in Baylor’s pursuit of R1 designation.

“If we want to become a R1 institute, the facilities are definitely important,” Lee said. “If you don’t have the facilities or resources to do research, it’s hard to compete.”