A 448-Gb/s PAM4 FSO Communication With Polarization-Multiplexing Injection-Locked VCSELs Through 600 M Free-Space Link

Autor: Hsiao-Wen Wu, Hai-Han Lu, Wen-Shing Tsai, Yong-Cheng Huang, Jing-Yan Xie, Qi-Ping Huang, Shi-Cheng Tu
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: IEEE Access, Vol 8, Pp 28859-28866 (2020)
Druh dokumentu: article
ISSN: 2169-3536
DOI: 10.1109/ACCESS.2020.2972943
Popis: A 448-Gb/s four-level pulse amplitude modulation (PAM4) free-space optical (FSO) communication through 600 m free-space link was constructed, utilizing polarization-multiplexing injection-locked vertical-cavity surface-emitting lasers (VCSELs) for presentation. When uniting four-wavelength polarization-multiplexing and PAM4 modulation schemes, the transmission capacity of FSO communications is substantially multiplied, with an aggregate transmission rate of 448 Gb/s [56 Gb/s PAM4/wavelength × 4 wavelengths × 2 polarizations (xand y-polarizations)]. The results show that four 1.55 μm VCSEL transmitters with injection locking technique are sufficiently powerful for 448 Gb/s PAM4 signal transmission. Adopting a tunable optical band-pass filter and a polarization beam splitter for wavelength filtering and polarization de-multiplexing, the polarized wavelengths are effectually filtered and de-multiplexed in each polarized state. As the polarization state is well preserved in the scenario over 600 m free-space transmission, a sophisticated polarization tracker is not required in this proposed FSO communication. High bit error rate performance and accepted PAM4 eye diagrams are attained through 600 m free-space transmission. The four-wavelength polarization-multiplexing PAM4 FSO communication established here reveals the prominent benefits of high aggregate transmission capacity and long-distance free-space link.
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