Optical adaptive power transmission using APC-EDFA for turbulence-tolerant FSO communications

Area of Science:

• Optical Communications
• Free-Space Optics (FSO)
• Fiber Amplifiers

Background:

• Free-space optical communication systems face performance degradation due to atmospheric turbulence.
• Existing methods for mitigating turbulence often require complex channel state information (CSI) estimation.
• Erbium-doped fiber amplifiers (EDFAs) offer controllable gain characteristics.

Purpose of the Study:

• To propose and analyze a novel adaptive power transmission technique for turbulence-tolerant FSO communications.
• To leverage automatic power control (APC) in EDFAs for real-time optical power adjustment.
• To reduce the need for explicit CSI estimation in FSO systems.

Main Methods:

• Utilizing the quasi-stationary nature of turbulence channels and EDFA's average power-dependent gain.
• Optically conveying upstream channel state information (CSI) to the downstream signal via APC-EDFA.
• Employing channel inversion and orthogonal polarization for signal transmission.
• Analyzing performance under varying APC-EDFA dynamic gain frequencies and downstream/upstream power ratios.

Main Results:

• Demonstrated effective turbulence suppression through adaptive downstream signal power.
• Achieved efficient transmitted power utilization.
• Showcased a reduction in the required signal-to-noise ratio (SNR) without CSI estimation.
• Validated the adaptive power control mechanism via simulations.

Conclusions:

• The proposed APC-EDFA based adaptive power transmission is a viable solution for robust FSO communications.
• This technique significantly improves system performance in the presence of atmospheric turbulence.
• The method offers a practical approach to enhancing FSO link reliability and efficiency.