Scientists have created the world's thinnest lens, which at just 6.3 nm (nanometers) thick is one two-thousandth the thickness of a human hair. The team from the Australian National University (ANU) says the lens was made using molybdenum disulphide crystal, and could be key in the miniaturization of cameras and the development of flexible computer displays.
In recent years we've seen a number of developments focusing on creating ultra-thin lenses. These have included using gold nanoantennas, graphene microlens, and new methods of creating diffractive lenses. But now a team led by Dr Yuerui (Larry) Lu from the ANU Research School of Engineering has set a new record with its own lens.
The researchers created the lens using molybdenum disulphide crystal, which is in a class of materials known as chalcogenide glasses. These have flexible electronic characteristics which make them popular for use in high-technology components.
Single layers of molybdenum disulphide 0.7 nm thick have also been found to have remarkable optical properties, appearing to a light beam to be 50 times thicker, at 38 nm. This property, known as optical path length, determines the phase of the light and controls interference and diffraction of light as it propagates.
To create the ultra-thin lens, a 6.3 nm thick crystal – 9 atomic layers – was peeled off from a larger piece of molybdenum disulphide using sticky tape. A focussed ion beam was then used to shave off layers atom by atom until a dome-shaped 10-micron radius lens was left. The resulting lens is said to outshine previous record-setting ultra-thin flat lenses, made from 50 nm thick gold nano-bar arrays.
"The capability of manipulating the flow of light in atomic scale opens an exciting avenue towards unprecedented miniaturization of optical components and the integration of advanced optical functionalities." says Dr Lu.
It's thought the findings could help in the development of flexible computer displays as well as the miniaturization of cameras. Dr Lu says an array of micro lenses could also be used to mimic the compound eyes of insects.
This study is published in the Nature serial journal Light: Science and Applications.