3. Transmission capacity by fiber type

Standard fiber, also known as NDSF (Non Dispersion Shifted Fiber ), has zero chromatic dispersion at 1,320 nm, which is equal to +18 ps · nm ^–1 · km ^–1 at 1,550 nm. The first cable to use optical amplification (TAT12/13) was equipped with a dispersion-shifted fiber called DSF (Dispersion Shifted Fiber ), which was characterized by near-zero chromatic dispersion at the single transmission wavelength (1,560 nm). However, in the case of WDM transmission, DSF is no longer appropriate, as the different wavelengths propagate at the same speed, generating a four-wave mixing effect that severely penalizes transmission quality. To remedy this problem, a new type of fiber called NZDSF (Non-Zero-Dispersion-Shifted Fiber ) has been introduced.