Smartphone cameras are an increasingly familiar part of everyday life. Beyond photos and videos, we’re using them to shop online, clear bank transactions and unlock the devices themselves. However, to capture ‘zoomed in’ visuals like professional cameras do, smartphones often either need multiple lenses, or powerful software that enhances images post-shot. This can pose design challenges for engineers trying to pack more parts and performance into a pocket-sized device.
At the A*STAR Institute of Materials Research and Engineering (A*STAR IMRE), a team of researchers might have found a solution: tuneable metalenses. A new study reveals that the way some layered 2D optical materials bend and scatter light can be altered with a touch of electricity, opening up possibilities for entirely new device designs.
“With a typical camera, you adjust the focus and brightness of images by changing the camera’s focal length: the distance between its multiple built-in lenses. This changes the angles of light passing through the lenses to reach the camera sensor,” said Jinghua Teng, an A*STAR IMRE Senior Principal Scientist. “Imagine a camera with just one lens, but one you could directly, physically change the optical properties of, on demand, to make the same image adjustments.”
During a joint investigation of potential 2D ferroelectric flat lens materials with the A*STAR Institute of High Performance Computing (A*STAR IHPC); Nanyang Technological University, Singapore; Singapore University of Technology and Design; and the Technical University of Denmark, Teng and colleagues discovered that one candidate—CuInP2S6, or CIPS—offered that intriguing optical flexibility. By simply applying an electric field to CIPS, they triggered a phenomenon known as the linear electro-optic (e-o) effect, which altered the angles of light passing through the material.
“Beyond cameras, this ability could lead to sensors, integrated photonics and other advanced optical devices with adjustable components, making the system more compact and versatile,” said Teng.
The team, which included A*STAR IMRE Senior Scientist Yuanda Liu and A*STAR IHPC Distinguished Principal Scientist Yong-Wei Zhang, tested CIPS and then applied it in a prototype flat lens design. They not only confirmed—for the first time in scientific literature—that 2D ferroelectrics like CIPS had tuneable e-o properties, but found that CIPS had a high e-o coefficient: a measure of how effectively it changed its optics in response to electricity.
“CIPS’s high e-o coefficient and electrical modulation efficiency mean that devices made from it can operate faster and use less energy, which is a big plus for mobile devices,” said Teng.
“CIPS’s performance in this area is also comparable to traditional and widely-used electrooptical materials such as lithium niobate (LiNbO3), making it a viable commercial option,” added Liu.
Besides being transparent across a wide range of light wavelengths, CIPS is also electronically compatible with various materials, making it suited for developing multifunctional mixed-material components in future photonic and optoelectronic devices.
“CIPS’s stability at room temperature operations also means it doesn’t need additional cooling when used in consumer electronics,” noted Zhang.
The team has filed a patent for their CIPS-based device and is searching for other 2D ferroelectric materials that could outperform CIPS, as well as supporting technologies for large-scale metalens fabrication.
The A*STAR-affiliated researchers contributing to this research are from the A*STAR Institute of Materials Research and Engineering (A*STAR IMRE) and A*STAR Institute of High Performance Computing (A*STAR IHPC).
