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Dynamic aerosol and dynamic air-water interface curvature effects on a 2-Gbit/s free-space optical link using
Haoqian Song1, Runzhou Zhang1, Nanzhe Hu1
1University of Southern California, Los Angeles 90089, CA, USA.
Nanophotonics (Berlin, Germany)
|December 5, 2024
Summary
Orbital-angular-momentum (OAM) beams experience significant degradation from dynamic air-water interfaces, including aerosol and surface curvature. These effects cause modal power loss and coupling, impacting optical communication links.
Area of Science:
- Optical physics
- Atmospheric optics
- Fluid dynamics
Background:
- Orbital-angular-momentum (OAM) beams offer unique properties for optical communications.
- Dynamic air-water interfaces present complex challenges due to aerosol presence and surface curvature.
- These interface dynamics can degrade OAM beam quality through scattering, absorption, and wavefront distortion.
Purpose of the Study:
- To experimentally investigate the degradation of OAM beams propagating through dynamic air-water interfaces.
- To quantify the effects of aerosol and water surface curvature on OAM beam characteristics.
- To assess the performance impact on a multiplexed optical communication link.
Main Methods:
- Experimental setup to simulate dynamic air-water interface conditions.
- Controlled introduction of varying aerosol concentrations (attenuation coefficient).
- Controlled introduction of varying surface curvature (variance of curvature slope).
- Measurement of modal power loss and modal power coupling for OAM beams.
- Demonstration of a 2-Gbit/s OAM multiplexed communication link.
Main Results:
- Increased aerosol strength led to a 4 dB power coupling ratio increase from OAM-1 to OAM+2.
- Increased curvature strength resulted in an 11 dB power coupling ratio increase from OAM-1 to OAM+2.
- Combined aerosol and curvature effects caused up to 2 dB higher modal power loss compared to individual effects.
- Received power on OAM-1 fluctuated by ~6 dB within 220 ms under combined effects.
- A 3 dB power penalty was observed for a 2-Gbit/s OAM multiplexed link under combined dynamic effects.
Conclusions:
- Dynamic air-water interfaces significantly degrade OAM beam quality.
- Both aerosol and surface curvature contribute to modal power loss and coupling.
- These degradations have a measurable impact on the performance of OAM-based optical communication systems.
- Understanding these effects is crucial for robust free-space optical communication design.
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