In a groundbreaking achievement, an international research team led by Japan's National Institute of Information and Communications Technology (NICT) has shattered records by achieving an aggregate optical transmission bandwidth of 37.6 THz. This remarkable feat translates to an astonishing data transfer rate of 402 terabits per second (Tb/s) – a milestone that promises to revolutionize our communication infrastructure.
The Quest for Bandwidth
As the internet and data services continue to expand, the demand for greater optical transmission bandwidth has surged. Researchers have turned their attention to wavelength-division multiplexing (WDM) technology, which leverages new spectral windows to enhance fiber optic transmission capacity. By tapping into previously unused transmission windows within existing optical fibers, we can expand their capacity without massive capital investments.
However, achieving this beyond the standard low-loss region of silica fibers requires innovative amplification solutions that go beyond the traditional erbium-doped fiber amplifiers (EDFAs) commonly used in C-band or C+L-band systems.
A Remarkable Demonstration
In their recent demonstration, the research team extended dense wavelength-division multiplexing (DWDM) transmission across all major transmission bands within the low-loss window of standard optical fibers. This breakthrough allowed them to achieve over 1,500 parallel transmission channels within the 37.6 THz (275 nm) optical bandwidth.
Collaborating with partners, NICT built the world's first DWDM transmission system covering the O to U bands, all within standard commercial optical fibers. This transmission setup utilized six variants of EDFAs, providing gain across the O/E/S/C/L bands. Additionally, it incorporated discrete (U-band) and distributed Raman amplification, along with a novel optical gain equalizer for O/E-band balance.
The High-Speed Journey
The wideband DWDM signal, spanning 275 nm (37.6 THz) from 1,281.2 nm to 1,649.9 nm across O/E/S/C/L/U bands, traveled through 50 kilometers of water-peak-suppressed optical fiber. Employing dual-polarization (DP) and quadrature amplitude modulation (QAM) with up to 256 symbols, they achieved remarkable data transfer rates. After this 50-kilometer journey, the estimated generalized mutual information (GMI) reached a staggering 402 Tb/s – over 25% higher than the previous record for single-mode fiber (SMF) data transfer rates, with a 35% increase in cumulative transmission bandwidth.
Unleashing the Potential
These results underscore the potential of new amplifiers and broadband spectral shaping techniques to enhance information transmission capabilities in both existing and future optical fibers. As we anticipate the surge in data rates required for 5G and beyond, utilizing new wavelength regions will enable higher data transfer rates while extending the lifespan of our existing fiber networks. Moreover, these innovations will meet the demands of next-generation communication services.
Looking ahead, NICT remains committed to advancing research and development in amplification technologies, components, and optical fibers. Their goal? To support new transmission windows and address both short-term and long-term application needs. As they continue to expand the compatibility of this high-capacity system with deployed optical fibers, the future of ultra-wideband transmission looks brighter than ever.
