FSO optical power adaptive compensation based on the position-sensitive detector and variable optical attenuators

Area of Science:

• Optical Engineering
• Free-Space Laser Communication
• Signal Processing

Background:

• Beacon light power in free-space laser communication attenuates with distance and atmospheric conditions, causing positioning errors in position-sensitive detectors (PSDs).
• PSDs can experience power saturation at short distances or with strong background light, compromising system performance.

Purpose of the Study:

• To propose and validate an adaptive optical power compensation method for PSDs in free-space laser communication.
• To mitigate beacon light attenuation and detector saturation issues, thereby improving positioning accuracy and system robustness.

Main Methods:

• Implemented an adaptive optical power compensation system for PSDs utilizing a variable optical attenuator (VOA).
• Employed spread-spectrum scrambling modulation for low-speed service communication on the beacon link.
• Utilized real-time power feedback for closed-loop control of beacon transmission power via the VOA.

Main Results:

• The VOA integration increased the detection system's input power dynamic range by over 30 dB.
• The power compensation system exhibited an overall response delay of less than 300 µs.
• Suppressed a 10 Hz sinusoidal power disturbance (3 dB amplitude), reducing output power standard deviation to 0.042 dB.

Conclusions:

• The proposed adaptive optical power compensation method effectively enhances the dynamic range and stability of beacon detection in free-space laser communication.
• The system demonstrates rapid response and significant suppression of power fluctuations, crucial for reliable optical communication.
• This VOA-based approach offers a robust solution for overcoming challenges posed by varying optical power levels in free-space laser systems.