Freeing up optical communication by harnessing vectorial light

For militaries and governments around the world, secure communication is essential. Free-space optical communication (FSO) is a compelling tactic involving sending information using laser beams, which are more difficult to intercept and decode than standard radio systems. But atmospheric turbulence and suspended aerosols easily disrupt these beams by clouding information and making the beams easier to hack.

Cai et al. used the nonseparability of vectorized light to make FSO more robust to atmospheric disruption and decoding while increasing the degrees of freedom for information that can be sent. Previous attempts to mitigate atmospheric turbulence have required complex and costly additional hardware, signal processing algorithms, and sensors.

“For FSO, the core challenges include mitigating channel interference caused by atmospheric turbulence and reducing the risk of eavesdropping during transmission,” said author Jing Du. “We gradually recognized that the nonseparability of vector beams holds great potential to address these practical challenges.”

The researchers began by simulating how vector-structured light would transmit information under two different turbulence scenarios and three eavesdropping scenarios. Then, they built and optimized an experimental system to verify the process, finding that vectorized light indeed carried more complexity and was more difficult for adversaries to decode or atmospheric turbulence to rattle.

Next, the team hopes to test different structured light fields in FSO to determine how their distinct physical properties affect information transmission. For now, the team is encouraged by the promise of vectorized light.

“Our proposed FSO approach can simultaneously mitigate channel interference induced by atmospheric turbulence and improve the transmission security of the system,” said Du.

Source: “Free-space secure optical communication based on the nonseparability of vectorial structured light,” by Mingze Cai, Zhenyu Wan, Yuzhao Cao, Runshi Wang, Yu Zhang, Jing Du, and Jian Wang, APL Photonics (2026). The article can be accessed at https://doi.org/10.1063/5.0327437 .