Compensation-free high-dimensional free-space optical communication using turbulence-resilient vector beams

Area of Science:

• Optical communication
• Free-space optics
• Information theory

Background:

• Free-space optical communication offers high bandwidth and security for mobile nodes.
• Atmospheric turbulence distorts spatial modes, degrading data transmission quality.
• Adaptive optics are typically required to compensate for turbulence effects.

Purpose of the Study:

• To demonstrate a turbulence-resilient communication protocol for free-space optical links.
• To transmit high-dimensional information through turbulent channels without adaptive optics.
• To experimentally validate a vector-beam-based approach for robust optical communication.

Main Methods:

• Experimental demonstration of spatial polarization differential phase shift keying (SPDPSK).
• Utilizing vector beams to encode information.
• Employing a controllable turbulence cell to simulate atmospheric conditions.
• Measuring channel capacity under varying turbulence intensities.

Main Results:

• Achieved a channel capacity of 4.84 bits per pulse using 34 vector modes with a scintillation index of 1.09.
• Transmitted data reliably through stronger turbulence (scintillation index of 1.54) using 18 vector modes, achieving 4.02 bits per pulse.
• Demonstrated successful high-dimensional information transfer without adaptive optics.

Conclusions:

• SPDPSK is an effective protocol for turbulence-resilient free-space optical communication.
• Vector beams enhance the robustness of optical communication in the presence of atmospheric turbulence.
• The developed method offers a promising solution for secure, high-bandwidth communication in challenging environments.