AsianScientist (Mar. 17, 2016) – Scientists in Australia have created the world’s thinnest lens—one two-thousandth the thickness of a human hair—paving the way for flexible computer displays and miniature cameras. This study was published in Light: Science and Applications.
Lead researcher Dr. Lu Yuerui from the Australian National University’s Research School of Engineering said the discovery hinged on the remarkable potential of the molybdenum disulphide crystal. Molybdenum disulphide is in a class of materials known as chalcogenide glasses, that have flexible electronic characteristics that have made them popular for high-technology components.
“This type of material is the perfect candidate for future flexible displays,” said Lu. “We will also be able to use arrays of micro lenses to mimic the compound eyes of insects.”
The 6.3-nanometer lens outshines previous ultra-thin flat lenses made from 50-nanometer thick gold nano-bar arrays.
“Molybdenum disulphide is an amazing crystal. It survives at high temperatures, is a lubricant, a good semiconductor and can emit photons too,” said Lu.
“The capability of manipulating the flow of light on an atomic scale opens an exciting avenue towards unprecedented miniaturization of optical components and the integration of advanced optical functionalities.”
Lu’s team created their lens from a crystal 6.3-nanometers thick—nine atomic layers—which they had peeled off a larger piece of molybdenum disulphide with sticky tape.
They then created a ten-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, at 0.7 nanometers thick, had remarkable optical properties. It appeared to be 50 times thicker, at 38 nanometers, under a light beam. This surprising property, known as optical path length, determines the phase of the light and governs interference and diffraction of light.
Lu’s collaborator, Assistant Professor Yu Zongfu 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.
The article can be found at: Yang et al. (2016) Atomically Thin Optical Lenses and Gratings.
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Source: Australian National University.
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