Femtosecond Filament Coupled with Structured Light for Free-Space Optical Communication

The generation of a laser filament through clouds produces a shockwave which displaces the small water droplets from the air to create a quasi-transparent channel through which, information can be transmitted. We present a robust method that utilizes the channel for free-space optical communication using structured light beams coupled with a femtosecond filament. Structured light beams based on their spatial profiles are perfectly suited to propagate around the filament. We have also developed a 4-bit communication channel using a segmented annular beam. Our system demonstrates resilience to noise and is unaffected by the filament. This method can improve the scalability, robustness, and capacity of the free optical channel.