NTT constructed the world’s first broadband all-at-once amplification repeater using optical parametric amplification (OPA), realizing the world’s largest 14.1 terahertz bandwidth for an OPA repeater, and carried out all-at-once optical amplification repeater transmission experiments for wavelength multiplexed signals. 
In the demonstration, using the technology independently developed by NTT, it maintained the optical amplification repeater interval of 80 kilometers without reducing the transmission capacity, and realized the long-distance batch optical amplification repeater transmission over 400 kilometers. The optical amplification repeater configures an optical amplification repeater that can make the most of the bandwidth of optical parametric amplification, and by integrating amplification bandwidth control technology, broadens the optical amplification bandwidth to 14.1 terahertz, more than three times the conventional bandwidth. 
NTT demonstrated the feasibility of a technology that expands the wavelength resources available on optical fibers to more than three times that of conventional amplifying repeaters. This is expected as a future basic technology that will lead to expansion of APN in IOWN/6G.