An MIT research effort has developed an active zoom metalens that requires no deformation or physical motion for applications such as optical devices, drones, and cameras.

According to Memes Consulting, the Massachusetts Institute of Technology (MIT) recently designed a metalens with adjustable focal length, which can focus objects at different distances without changing the position or shape of the lens.

The superlens can achieve zoom without physically moving its lens elements, or using various mechanical actuators to achieve physical movement, which will bring new applications such as mobile phones or night vision goggles.

Instead of traditional optical materials, the metalens developed at MIT are made of a transparent compound that can change its solid phase (atomic structure) and thus its optical properties. The research has been published in the journal Nature Communications.

"Typically, it's very difficult to adjust the optical properties of an optical component after it's been fabricated. That's why the type of platform we've developed is like a holy grail for optical engineers, allowing metalens to zoom over a wide range. ” said Mikhail Shalaginov of the Massachusetts Institute of Technology.

Metasurfaces, with new properties due to nanostructures or other modifications to the surface of materials, are increasingly attractive for many applications, and researchers are currently developing a variety of fabrication techniques to construct metasurfaces. Despite the limited tuning range and optical efficiency of such elements, actively tunable metasurfaces have been the subject of research for some time.

According to the MIT study, wavefront shaping via active metasurfaces is a largely unexplored challenge due to the complexity of the design and the need for computationally efficient design and verification methods.

The conundrum was solved by using a phase-change compound of germanium, antimony and tellurium called GST, which is able to switch between transparent and opaque states when supplied with the right amount of heat. MIT modified this class of compounds with an additional addition of selenium to form GSST. When this type of material changes phase, it changes from an amorphous structure to a crystalline structure, which affects the refractive power of the material, but does not affect its transparency.