As an alternative to traditional adaptive optics systems, wavefront shaping techniques show promise in controlling light propagation through turbulent channels. This study explores the feasibility of measuring the transmission matrix and using it to enhance communication in turbulent conditions.
Vectorial states of light, where the polarization is inhomogeneously distributed in space, have gained considerable interest in the context of structured light, but their inherent parity has hitherto been overlooked. Now, parity has been revealed as a fundamental degree of freedom in vectorial light that can be acted on with customized metasurfaces, opening a path to high capacity classical and quantum communication.
When light propagates through aberrated optical systems, the resulting degradation in amplitude and phase has deleterious effects, for example, on resolution in imaging, spot sizes in focusing, and the beam quality factor of the output beam. Traditionally, this is either pre- or post-corrected by adaptive optics or phase conjugation. Here, we consider the medium as a complex channel and determine the corresponding eigenmodes which are impervious of the channel perturbation. We employ a quantum-inspired approach and apply it to the tilted lens as our example channel, a highly astigmatic system that is routinely used as a measure of orbital angular momentum. We find the eigenmodes analytically, show their robustness in a practical experiment, and outline how this approach may be extended to arbitrary astigmatic systems.
Structured light is routinely used in free-space optical communication channels, both classical and quantum, where information is encoded in the spatial structure of the mode for increased bandwidth. Unlike polarisation, the spatial structure of light is perturbed through such channels by atmospheric turbulence, and consequently, much attention has focused on whether one mode type is more robust than another, but with seemingly inconclusive and contradictory results. Both real-world and experimentally simulated turbulence conditions have revealed that free-space structured light modes are perturbed in some manner by turbulence, resulting in both amplitude and phase distortions. Here, we present complex forms of structured light which are invariant under propagation through the atmosphere: the true eigenmodes of atmospheric turbulence. We provide a theoretical procedure for obtaining these eigenmodes and confirm their invariance both numerically and experimentally.
Structured light is routinely used in free-space optical communication channels, both classical and quantum, where information is encoded in the spatial structure of the mode for increased bandwidth. Both real-world and experimentally simulated turbulence conditions have revealed that free-space structured light modes are perturbed in some manner by turbulence, resulting in both amplitude and phase distortions, and consequently, much attention has focused on whether one mode type is more robust than another, but with seemingly inconclusive and contradictory results. We present complex forms of structured light that are invariant under propagation through the atmosphere: the true eigenmodes of atmospheric turbulence. We provide a theoretical procedure for obtaining these eigenmodes and confirm their invariance both numerically and experimentally. Although we have demonstrated the approach on atmospheric turbulence, its generality allows it to be extended to other channels too, such as aberrated paths, underwater, and in optical fiber.
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