Single-Shot Phase Diversity Wavefront Sensing in Deep Turbulence via Metasurface Optics
This work addresses the need for compact, low-latency wavefront sensing to enhance the range and accuracy of free-space optical communication systems, representing an incremental improvement over existing phase diversity methods.
The paper tackled the problem of wavefront sensing degradation in deep turbulence for free-space optical communication by using a nanostructured birefringent metasurface optic, resulting in an average 16-fold increase in signal from the corrected beam in simulations and experiments.
Free-space optical communication (FSOC) systems offer high-bandwidth and secure communication with minimal capital costs. Adaptive optics (AO) are typically added to these systems to decrease atmospheric channel losses; however, the performance of traditional AO wavefront sensors degrades in long-range, deep turbulence conditions. Alternative wavefront sensors using phase diversity can successfully reconstruct wavefronts in deep turbulence, but current implementations require bulky setups with high latency. In this work, we employ a nanostructured birefringent metasurface optic that enables low-latency phase diversity wavefront sensing in a compact form factor. We prove the effectiveness of this approach in mid-to-high turbulence (Rytov numbers from 0.2 to 0.6) through simulation and experimental demonstration. In both cases an average 16-fold increase in signal from the corrected beam is obtained. Our approach opens a pathway for compact, robust wavefront sensing that enhances range and accuracy of FSOC systems.