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Crosstalk mitigation in a free-space orbital angular momentum multiplexed communication link using 4×4 MIMO
Optics Letters
|August 1, 2014
Summary
This study mitigates crosstalk in free-space optical links using 4x4 multiple-input-multiple-output (MIMO) equalization. MIMO processing significantly improves signal quality and bit-error-rate (BER) performance, reducing power penalties.
Area of Science:
- Optical Communications
- Free-Space Optics
- Signal Processing
Background:
- Orbital Angular Momentum (OAM) multiplexing enables high-capacity free-space optical (FSO) data links.
- Weak turbulence in FSO links induces inter-channel crosstalk, degrading signal performance.
- Heterodyne detection is a common method for OAM-based FSO systems.
Purpose of the Study:
- To demonstrate crosstalk mitigation in an OAM-multiplexed FSO data link.
- To evaluate the effectiveness of 4x4 multiple-input-multiple-output (MIMO) equalization.
- To improve signal quality and bit-error-rate (BER) performance under turbulent conditions.
Main Methods:
- Implementing a 4x4 MIMO equalization scheme.
- Utilizing an OAM-multiplexed free-space data link with heterodyne detection.
- Transmitting four OAM beams, each carrying a 20 Gbit/s quadrature phase-shift keying (QPSK) signal through weak turbulence.
Main Results:
- Experimental results show significant improvement in signal quality due to MIMO processing.
- Bit-error-rate (BER) performance was enhanced, with a power penalty reduction of over 4 dB at a BER of 3.8x10^-3.
- Crosstalk induced by weak turbulence was effectively mitigated.
Conclusions:
- 4x4 MIMO equalization is a viable technique for crosstalk mitigation in OAM-multiplexed FSO links.
- MIMO processing enhances the robustness and performance of OAM-based FSO communication systems.
- The demonstrated approach offers a practical solution for improving the reliability of high-speed FSO data transmission.
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