Effect of Wavefront Distortion on the Performance of Coherent Detection Systems: Theoretical Analysis and Experimental Research

Atmospheric turbulence causes signal beam wavefront distortion at the receiving end of a coherent detection system, which decreases the system mixing efficiency. Based on the coherent detection theory, this study establishes a mathematical model of wavefront distortion with mixing efficiency and mix...

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Bibliographic Details
Published in:Photonics 2023-04, Vol.10 (5), p.493
Main Authors: Yang, Shangjun, Xing, Tian, Ke, Chenghu, Liang, Jingyuan, Ke, Xizheng
Format: Article
Language:English
Subjects:
Algorithms
Analysis
Astigmatism
Atmospheric research
Atmospheric turbulence
Closed loops
Coherence
Communications systems
Control theory
Detectors
Distortion
Efficiency
Experimental research
Feedback control
Lasers
Mathematical models
mixing efficiency
mixing gain
Noise
Optical wireless
Random variables
receive aperture
Sensors
Technology application
Theoretical analysis
Turbulence intensity
Wave fronts
wavefront correction
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Summary:Atmospheric turbulence causes signal beam wavefront distortion at the receiving end of a coherent detection system, which decreases the system mixing efficiency. Based on the coherent detection theory, this study establishes a mathematical model of wavefront distortion with mixing efficiency and mixing gain. It also analyzes the improvement limits of wavefront correction on mixing efficiency and mixing gain under different atmospheric turbulence intensities and experimentally measures them. Simulation results show that the mixing efficiency can be improved to 51%, 55%, and 60% after correcting for tilt, defocus, and astigmatism terms, respectively, when turbulence intensity D/r0 is 2. The mixing gain with homodyne detection is 3 dB higher than heterodyne detection. Meanwhile, the wavefront correction orders required for optimal mixing efficiency are higher than the heterodyne correction order. In the experiment, Haso4 NIR + DM 40 was used, and the turbulence intensity D/r0 was 2. After the closed-loop control algorithm corrects the tilt, defocus, and astigmatism terms, the indoor experimental results showed that the mixing efficiency is improved to 36%, 47%, and 62%, respectively. The outdoor experimental results showed that the mixing efficiency improved to 36%, 51%, and 68%, respectively.
ISSN:2304-6732
2304-6732
DOI:10.3390/photonics10050493