Highlights

Above

LEDs can also achieve laser-like directional light and be manipulated in similar ways to create any desired light output for multipurpose applications.

© Institute of Materials Research and Engineering (IMRE)

Shaping LED light with metasurfaces

28 May 2020

A*STAR scientists have managed to create a compact LED device with complete light control for multipurpose applications.

Since they were invented in the early years of the 20th century, light-emitting diodes (LEDs) ushered in a new era in optical technology. LEDs are cheap, bright and efficient light sources. However, due to the incoherent and non-directional nature of the light they emit, LEDs are thought to be inferior to lasers. Powerful laser beams have seen a variety of applications, from communication to medicine and industry using sophisticated optical manipulation.

Now, scientists at the A*STAR’s Institute of Materials Research and Engineering (IMRE) and Institute for High Performance Computing (IHPC), in collaboration with Nanyang Technological University, have demonstrated that the humble LED can be transformed to obtain laser-like directional light and be manipulated in similar ways to create any desired light output.

“LEDs typically emit light in all directions, but we wondered if we could concentrate LED light into a more directional, laser-like beam,” said first author Egor Khaidarov, a Scientist from IMRE. “Such a collimated light beam could then be shaped using metasurfaces, which manipulate light at the nanoscale using sub-wavelength structures, making the overall size of the device highly compact,” explained Zhengtong Liu, a Scientist from IHPC involved in the study.

To concentrate the LED light, the A*STAR team decided to use a Fabry-Perot resonant cavity, which is a pair of parallel mirrors that can amplify a source of light. They first fabricated a micrometer-thick resonant cavity LED by using a commercial LED wafer on a gold base. Gold functioned as the first mirror; on top of the LED they deposited several dielectric layers which acted as the second mirror. As expected, they found that the optical cavity successfully concentrated the LED light into a narrow angle, directional beam.

Khaidarov further fabricated two different metasurfaces on top of the resonant cavity LED¬—one designed to deflect light at an angle and another designed to twist light into an ‘optical vortex’, with the intensity profile resembling a donut. In both cases, the experimental results matched Liu’s simulations, showing that the resonant cavity LED light was compatible with the metasurfaces.

“This work shows how a metasurface, resonant cavity and LED can be integrated to produce compact, self-contained and power-efficient devices with special functionalities,” Liu said. These devices could have a wide range of applications, such as in optical telecommunications, smart lighting, display screens and projectors. “They could even replace lasers in some applications, with their lower power consumption and relaxed safety regulations,” Khaidarov added.

Moving forward, the team hopes to expand this technology to industrial-level light sources and electrically-driven devices, as well as experiment with broadband collimators that can concentrate and amplify a wider range of wavelengths.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering (IMRE) and Institute for High Performance Computing (IHPC).

Want to stay up to date with breakthroughs from A*STAR? Follow us on Twitter and LinkedIn!

References

Khaidarov, E., Liu, Z., Paniagua-Domínguez, R, Ha, S. T., Valuckas, V., Liang, X., Akimov, Y., Bai, P., Png, C. E., Demir, H. V., Kuznetsov, A. I. Control of LED Emission with Functional Dielectric Metasurfaces. Laser and Photonics Reviews 14, 1 (2019): 1900235. | article

About the Researchers

Egor Khaidarov is a Scientist at A*STAR’s Institute of Materials Research and Engineering. He has recently graduated from Nanyang Technological University with a PhD degree in electrical and electronic engineering. His interests include metasurfaces, LEDs, nanostructure design and machine learning.

Zhengtong Liu

Scientist

Institute of High Performance Computing
Zhengtong Liu received his BSc in Electrical Engineering from Peking University, China, in 2000; MPh in Electrical and Electronic Engineering from Hong Kong University of Science and Technology, Hong Kong, China, in 2003; and PhD in Electrical and Computer Engineering from Purdue University, US, in 2010. In 2010 he joined A*STAR’s Institute of High Performance Computing, Singapore, where he is now a Scientist. His research interests include plasmonics, nano-photonics, metamaterials and computational electromagnetics.

This article was made for A*STAR Research by Wildtype Media Group