Researchers Develop Metafiber with Tunable Focusing 

Researchers at Leibniz IPHT have developed a metafiber whose focus can be adjusted solely through the intensity of light. This approach allows optical systems to be miniaturized and dynamically reconfigured. The metafiber is based on a dual-core fiber with a 3D nanoprinted hologram on its end face. The optical power in each core can be controlled independently. Changing the ratio of the input powers shifts the focal point of the emitted light – without any mechanical components.

“We use light to control light,” says Prof. Markus Schmidt, head of the Fiber Photonics research department at Leibniz IPHT. “This enables ultrafast and highly precise focus adjustment and is particularly well-suited for applications where conventional lenses are too slow or bulky.” The structure on the fiber surface was fabricated using 3D nanoprinting at Leibniz IPHT, and the dual-core fiber was produced by the Competence Center for Optical Fiber Technology (KSF) team. 

A New Approach for Compact Optical Systems The researchers demonstrate that, using this method, the focal point can be shifted over several micrometers in real time with high precision. This opens up new possibilities for microscopy, optical data transmission, and adaptive, fiber-based sensing, where measurement points or focal positions need to be adjusted dynamically.

“What makes this concept particularly compelling is its simplicity,” Schmidt adds. “It shows that complex optical functions can be integrated directly into a glass fiber without additional mechanical elements.”

Original publication: https://doi.org/10.1038/s41377-025-01903-0