World Thinnest Micro Lens Discovered, to Revolutionize Nanotech Applications

Molybdenum disulphide crystal lens (ANU)

Molybdenum disulphide crystal lens (ANU)

Australian researchers have created the world’s thinnest lens, thousand times thinner than a human hair, which will revolutionize the nanotechnology frontiners into new smartphones, medical devices and miniature cameras.

Led by Yuerui Larry Lu from ANU Research School of Engineering, they discovered the potential of the molybdenum disulphide crystal which fits in the requirement to produce future lenses for visual devices.

“This type of material is the perfect candidate for future flexible displays,” said Dr Lu, leader of Nano-Electro-Mechanical System (NEMS) Laboratory in the ANU Research School of Engineering.”We will also be able to use arrays of micro lenses to mimic the compound eyes of insects.”

The 6.3-nanometre lens outshines previous ultra-thin flat lenses, made from 50-nanometre thick gold nano-bar arrays, known as a metamaterial.

Molybdenum disulphide survives at high temperatures, is a lubricant, a good semiconductor and can emit photons too with capability of manipulating the flow of light in atomic scale opens an exciting avenue towards unprecedented miniaturisation of optical components and the integration of advanced optical functionalities, he explained.

Yuerui Lu, who received his Ph.D. degree from Cornell University, the school of Electrical and Computer Engineering, in 2012, joined the Australian National University as research fellow and lecturer under the Future Engineering Research Leadership Fellowship.

In October 2015, he was promoted to Senior Lecturer at the ANU. His research interests include MEMS/NEMS sensors and actuators, nano-manufacturing technologies, renewable energy harvesting, biomedical novel devices, nano-materials, nano-electronics, etc.

Molybdenum disulphide, known as chalcogenide glasses with flexible electronic characteristics can eb made from high-technology components. The team has created lens from a crystal 6.3-nanometres thick – 9 atomic layers – which they had peeled off a larger piece of molybdenum disulphide with sticky tape before creating a 10-micron radius lens, using a focussed ion beam to shave off the layers atom by atom, until they had the dome shape of the lens.

The team discovered that single layers of molybdenum disulphide, 0.7 nanometres thick, had remarkable optical properties, appearing to a light beam to be 50 times thicker, at 38 nanometres. This property, known as optical path length, determines the phase of the light and governs interference and diffraction of light as it propagates.

Then Assistant Professor Zongfu Yu at the University of Wisconsin, Madison, developed a simulation and showed that light was bouncing back and forth many times inside the high refractive index crystal layers before passing through. Molybdenum disulphide crystal’s refractive index, the property that quantifies the strength of a material’s effect on light, has a high value of 5.5.

Molybdenum disulphide crystal can be compared to a diamond, whose high refractive index causes its sparkle, is only 2.4, and water’s refractive index is 1.3.

This study is published in the Nature serial journal Light: Science and Applications.

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