Simultaneous high bandwidth data reception and irradiance variance monitoring for free space optical links

Free space optical communication (FSOC) provides high capacity and data security without the spectral allocation challenges of RF systems. These advantages have led to the proliferation of FSOC technology in terrestrial, air-to-ground, and space-based telecommunication network architectures. Propagation through the atmosphere introduces turbulence impacts on FSOC systems which include beam wander and optical scintillation. Optical scintillation causes both spatial and temporal distortions on the received beam, spanning many milliseconds and causing signal fading that can result in significant data loss. In-situ monitoring of scintillation experienced by a given FSOC system in operation can not only provide a better understanding of the underlying distribution functions of various scintillation conditions for link availability planning but also inform more efficient error correction protocol techniques that can better adapt to the changing atmospheric channel conditions. In previous work, we demonstrated a tone-based irradiance variance characterization approach that can provide real-time measurements of the scintillation index, power spectral density, and distribution function of scintillation using an FSOC system’s data modulation envelope. Here, we expand this capability to operate on modulation envelopes with data rates in excess of 1Gbps while simultaneous supporting high bandwidth data reception.