Enhanced Atmospheric Turbulence Resiliency With Successive Interference Cancellation DSP in Mode Division Multiplexing Free-Space Optical Links

• Published in: Journal of lightwave technology Vol. 40; no. 24; pp. 7769 - 7778
• Main Authors: Li, Yiming, Chen, Zhaozhong, Hu, Zhouyi, Benton, David M., Ali, Abdallah A. I., Patel, Mohammed, Lavery, Martin P. J., Ellis, Andrew D.
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.12.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive optics; Algorithms; Atmospheric turbulence; Bit error rate; Digital signal processing; Dual polarization (waves); Error correction; Free space optics; Free-space optical communication; free-space optics (FSO); Interference; Interference cancellation; Lanterns; MIMO communication; Mode division multiplexing (MDM); multiple-input multiple-output (MIMO); Multiplexing; Optical attenuators; Optical fibers; Polarization; Quadrature phase shift keying; Resilience; Spatial light modulators; successive interference cancellation (SIC); Symbols; turbulence
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2022.3209092

We experimentally demonstrate the enhanced atmospheric turbulence resiliency in a 137.8 Gbit/s/mode mode-division multiplexing free-space optical communication link through the application of a successive interference cancellation digital signal processing algorithm. The turbulence resiliency is further enhanced through redundant receive channels in the mode-division multiplexing link. The proof of concept demonstration is performed using commercially available mode-selective photonic lanterns, a commercial transponder, and a spatial light modulator based turbulence emulator. In this link, 5 spatial modes with each mode carrying 34.46 GBaud dual-polarization quadrature phase shift keying signals are successfully transmitted with an average bit error rate lower than the hard-decision forward error correction limit. As a result, we achieved a record-high mode- and polarization-division multiplexing channel number of 10, a record-high line rate of 689.23 Gbit/s, and a record-high net spectral efficiency of 13.9 b/s/Hz in emulated turbulent links in a mode-division multiplexing free-space optical system.