Researchers have developed an optical receiver capable of restoring chaotic signals in free-space optical communication links distorted by atmospheric turbulence. By using a system of optical antennas integrated into a programmable photonic chip, the receiver can adapt in real time, maintaining the integrity of the signal even in harsh atmospheric conditions. The study, conducted by a team of researchers led by Télécom Paris and the Politecnico di Milano, paves the way for the use of chaos-based encryption for secure, high-speed communications in hostile environments. The idea behind secure, chaos-based communication is to encode a secret message into a light signal, which appears so unpredictable and complex that it is almost impossible to decipher. However, when these chaotic signals travel in the real wireless world, they encounter a major obstacle: atmospheric turbulence, which distorts signals and compromises their security. The researchers addressed this problem by developing a new type of receiver which uses a system of optical micro-antennas integrated into a programmable photonic chip. The micro-antennas capture light from multiple points of view while the photonic chip self-calibrates in real time to rebuild these fragments into a secure and reliable chaotic signal. Even in the presence of heavy rain, wind, or pollutants, the signal can be fully retrieved. An optical receiver developed by researchers at Télécom Paris and the Politecnico di Milano captures chaotic signals with an optical micro-antenna and reconstruct them with a photonic chip. Courtesy of Politecnico di Milano. “Chaos is a robust system, but can only be used in cryptosystems if its inherent nature is fully preserved. Atmospheric turbulence degrades the optical signal and apparently destroys the properties of chaos, making it hard to maintain secure and reliable communications,” said Sara Zaminga of LTCI Télécom Paris at Institut Polytechnique de Paris. “With our approach, we're not just mitigating the effects of turbulence, we're completely restoring the chaos of light in all its intrinsic complexity.” “What makes this solution really special is its ability to adapt in real time,” said Andrés Martínez of Politecnico di Milano. “Our receiver automatically adjusts to changes in the amount of turbulence, ensuring a stable and secure channel of communication without the need for manual interference.” Chaos-based systems have an inherent advantage in that their unpredictability makes them naturally secure. However, atmospheric turbulence by its very nature has long been a major obstacle to wireless communications. The potential impacts of the advance go beyond secure communications. “In remote areas or emergency zones, places where traditional networks fail, a chaos-based, turbulence-resistant system could provide a secure connection when it's most needed,” said Francesco Morichetti, head of the Photonic Devices Lab at the Politecnico di Milano. The research was published in Light: Science & Applications (www.doi.org/10.1038/s41377-025-01784-3).