TOKYO, July 22, 2021 – A research team led by Benjamin J. Puttnam at the National Institute of Information and Communications Technology (NICT) reported having transmitted data over a distance of over 3000 km (1860 miles). ) at a rate of 319 Tbit / s and a transmission bandwidth greater than 120 nm, on the S, C and L bands.
The team used a 4-core optical fiber with an outer diameter of 0.125mm to transmit the data, setting a record for transmitting data over an optical fiber with a standard cladding diameter. The long distance transmission signal bandwidth consisted of 552 wavelength division multiplexing (WDM) channels.
The system uses WDM and a combination of optical amplification technologies to enable long distance transmission of 552 WDM channels ranging from 1487.8 to 1608.33 nm. The team built a transmission loop combining erbium and thulium doped fiber amplifiers with distributed Raman amplification along the fiber itself to allow wideband signal recirculation.
By combining various amplification technologies, the researchers built a transmission system that capitalized on the strengths of WDM technology.
The Raman amplification part of the transmission system. Courtesy of the National Institute of Information and Communication Technologies.
The system measured the achievable transmission rate with each channel with PDM-16QAM modulation at distances up to 3001 km, where the data rate of 319 Tbit / s was achieved.
In addition to the C and L bands typically used for high speed long distance transmission, researchers have included S band in their transmission. Until now, ICTs have only built transmission systems using WDM on C and L bands, along with advanced modulation technology, to explore high-speed transmission in optical fibers.
Although S-band transmission has led to several new records for transmission capacity in optical fibers, the transmission distance in S-band has so far been limited to a few tens of kilometers.
The NTIC team hopes that its completion will pave the way for systems capable of supporting optical communications at the speeds necessary for 5G and beyond. The reported transmission demonstrates the potential of spatial multiplexing (SDM) fibers to support short-term high-speed SDM fiber systems, provided they are compatible with existing cabling technologies. The standard 4-core cladding diameter fiber used for the demonstration is compatible with conventional cable infrastructure, and researchers believe its mechanical reliability is comparable to that of single-mode fibers.
A graphic illustrating transmission demonstrations using fibers 125 μm in diameter. Courtesy of the National Institute of Information and Communication Technologies.
NTIC said it plans to work to extend its transmission range to transoceanic distances, as well as continue to develop broadband and long distance data transmission systems to increase the transmission capacity of low-count multicore fibers. cores and other new SDM fibers.
The research was presented at International Conference on Fiber Optic Communications (OFC), which took place from June 6 to 11.