“Secure Free Space Optics Receiver”

Researchers in Paris and Milan have collaborated to develop an innovative secure receiver for free space optics (FSO). This new system incorporates optical antennas into a programmable optical processor (POP) photonic chip, enabling the receiver to dynamically adapt in real time. By doing so, the integrity of the signal is maintained even in challenging atmospheric conditions, ensuring reliable communication.

The groundbreaking work conducted by researchers at Télécom Paris and the Politecnico di Milano opens up possibilities for utilizing chaos-based encryption in establishing secure, high-speed FSO links in hostile environments. This advancement is crucial for applications that require robust and secure communication channels, such as military operations or critical infrastructure.

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Chaos-based communication involves encoding a key into a light signal that appears highly unpredictable and complex, making it extremely difficult to intercept or decipher. However, atmospheric disturbances pose a challenge by distorting transmissions and compromising the security of the communication. To address this issue, the researchers have developed a solution that enhances the resilience of chaos-based encryption in the face of atmospheric disruptions.

The micro-antennas integrated into the photonic chip play a crucial role in capturing light from multiple sources and self-calibrating in real time. This process allows the receiver to reconstruct fragmented signals into a secure and reliable chaotic signal, even under adverse conditions such as heavy rain, strong winds, or the presence of pollutants in the atmosphere.

The integrated photonic processor, fabricated through a multi-project wafer run by a commercial silicon photonics platform in Singapore, combines a 2D array of grating couplers and a POP. The design features an outer ring with a radius of 180 µm and an inner ring of 60 µm, housing multiple grating couplers and a central unit. The POP consists of a self-configuring binary mesh with balanced Mach-Zehnder interferometers, each equipped with thermal shifters and photodiodes for coherent signal processing.

“Chaos is a robust system, but its effectiveness in cryptosystems relies on preserving its inherent properties. Atmospheric turbulence can degrade optical signals and disrupt the chaos, jeopardizing secure communications. With our approach, we not only mitigate turbulence effects but also restore the intrinsic complexity of light chaos,” explained Sara Zaminga from LTCI Télécom Paris, Institut Polytechnique de Paris.

“In remote or emergency scenarios where traditional networks may fail, a turbulence-resistant chaos-based system could offer a secure connection when it is most critical,” highlighted Francesco Morichetti, the head of the Photonic Devices Lab at the Politecnico di Milano. This innovative technology holds promise for enhancing communication resilience in challenging environments and ensuring secure connectivity in vital situations.