Researchers have shown that data can be sent at more than 100 terabits per second (Tb/s) through a single optical fiber over 2,000 kilometers, a first for this class of long-haul transmission. 6 Tbit/s per fiber in a field environment. This result was made possibl by the reviewers in the transmission section of. Conventional optical fiber has a core that goes through the center for transmitting light. High-capacity, long-haul optical transmission systems are critical for building the next generation of. ◆ In a field environment where the signal propagation environment in optical fiber cables fluctuates due to external disturbances such as wind and rain, we succeeded for the first time in the world stable transmission experiment with the record field capacity of 455 terabits per second (more than. This tutorial discusses research progress on high-capacity optical transmission systems utilizing large-scale multiplexing either through space-division multiplexing (SDM) or through multi-band wavelength-division multiplexing (WDM). To date, Sumitomo Electric has developed a randomly coupled 4-core optical fiber, a randomly coupled 7-core optical.