Spatial multiplexing and optical PAM4 quadruple the date rate in optical fiber systems

This endeavor demonstrates a two-channel spatial division multiplexed (SDM) system and combines it with an all-optical four-level pulse amplitude modulation (PAM4) scheme to quadruple the data rate and presents the experimental setup, system model, as well as key results. The system initially introduces spatial reuse of optical frequencies in a single-core multimode optical fiber by transmitting two SDM channels, where both operate at 1310 nm. It then complements the two SDM channels with an all-optical PAM4 scheme to enable 2 bits/symbol and 40 Gbps optical transport while using only 10 Gbps sources. Since all sources operate at the same wavelength, it effectively achieves PAM16 efficiencies at the given wavelength. The system accomplishes these results without the use of dedicated PAM4 chipsets.