Abstract
A wavelength-division-multiplexing (WDM) four-level pulse amplitude modulation (PAM4) free-space optical (FSO)–underwater wireless optical communication (UWOC) integrated system with a channel capacity of 100 Gb/s is proposed and attainably demonstrated. Analytic results reveal that 1.8-GHz 405-nm blue-violet-light and 1.7-GHz 450-nm blue-light laser diodes (LDs) with two-stage light injection and optoelectronic feedback techniques are competently adopted for 100 Gb/s PAM4 signal transmission through a 500-m free-space transmission with 5-m clear ocean underwater link. Combining dual-wavelength WDM scenario with PAM4 modulation, the channel capacity of FSO–UWOC integrated systems is significantly enhanced with an aggregate transmission rate of 100 Gb/s (25 Gbaud PAM4/wavelength × 2 wavelengths). With doublet lenses in FSO, laser beam reducer and transmissive spatial light modulator in UWOC, a sufficiently low bit error rate of 10−9 and acceptable PAM4 eye diagrams are acquired. This demonstrated 100 Gb/s PAM4 FSO–UWOC integrated system with a WDM scenario is advantageous for the enhancement of a high-speed optical wireless link with long-reach transmission.
Highlights
F REE-SPACE optical (FSO) communication is an optical communication technology that utilizes light transmitting in free-space to transport data wirelessly for high-speed Internet, wireless broadband access, and mobile telecommunication [1], [2]
Combining WDM scenario and PAM4 modulation, the channel capacity is greatly improved with a gross transmission rate of 100 Gb/s
With the adoption of doublet lenses in free-space optical (FSO) communications, laser beam reducer and transmissive spatial light modulator (SLM) in Underwater wireless optical communication (UWOC) links, a sufficiently low bit error rate (BER) of 10−9 and qualified PAM4 eye diagrams are attained through a 500-m free-space transmission and 5-m clear ocean underwater link
Summary
F REE-SPACE optical (FSO) communication is an optical communication technology that utilizes light transmitting in free-space to transport data wirelessly for high-speed Internet, wireless broadband access, and mobile telecommunication [1], [2]. Underwater wireless optical communication (UWOC) systems present a platform for supporting present and developing applications, such as sea-floor resource mining, offshore exploration, and real-time high-definition video transmissions over. Date of publication December 18, 2019; date of current version April 1, 2020. Li is with the Department of Communication Engineering, National Taipei University, New Taipei City 23741, Taiwan Color versions of one or more of the figures in this article are available online at http://ieeexplore.ieee.org
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