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Feedback-enabled adaptive underwater twisted light transmission link utilizing the reflection at the air-water
Optics Express
|August 19, 2018
Summary
This study demonstrates non-line-of-sight underwater twisted light transmission using total internal reflection. An adaptive system stabilizes the link against environmental factors like wind and salinity.
Area of Science:
- Optical Communications
- Underwater Optics
- Laser Physics
Background:
- Line-of-sight (LOS) free-space optical (FSO) laser communication is common.
- Underwater wireless optical communication (UWOC) faces challenges from obstacles and complex environments.
- Total internal reflection (TIR) at the air-water interface enables non-line-of-sight (NLOS) links.
- Twisted light beams with orbital angular momentum (OAM) show promise for increasing UWOC capacity.
Purpose of the Study:
- To propose and experimentally demonstrate a NLOS UWOC link using twisted light and TIR.
- To develop an adaptive feedback system for stabilizing the optical link against interface fluctuations.
- To investigate the impact of environmental factors (wind, salinity, thermal gradients) on link performance.
Main Methods:
- Experimental setup for NLOS UWOC using twisted light beams.
- Implementation of a proof-of-concept adaptive feedback control system.
- Systematic study of environmental effects: wind-induced waves, salinity (turbidity), and thermal gradients.
Main Results:
- Successful demonstration of a NLOS underwater twisted light transmission link.
- Adaptive system effectively mitigated beam fluctuation and drift caused by interface changes.
- Wind-induced waves caused the most beam drift.
- Thermal gradients induced the most significant beam distortions.
- Salinity (turbidity) resulted in the highest optical power loss.
Conclusions:
- NLOS UWOC using twisted light and TIR is feasible.
- Adaptive optics are crucial for stable underwater optical communication.
- Environmental factors significantly impact UWOC link performance, with distinct effects from wind, salinity, and thermal gradients.
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