What’s the Difference Between G.652 and G.655?

Unlike zero-dispersion-shifted fiber (G.652) which has a zero-dispersion wavelength at 1310 nm, G.655 fiber is known as non-zero dispersion-shifted fiber (NZDSF) since the dispersion of 1550 nm is close to zero, but not zero. NZDSF overcomes the nonlinear effects in WDM systems, such as four-wavelength mixing (FWD), by moving the zero-dispersion wavelength outside the 1550nm operating window. G.655 fiber is specified at 1550 nm and 1625 nm. It has a small, controlled amount of chromatic dispersion in the C-band (1530-1560 nm), where amplifiers work best, and has a larger core area than G.652 fiber. There are two types of NZDSF, known as (-D)NZDSF and (+D)NZDSF. They have respectively a negative and positive slope versus wavelength. The attenuation parameter for G.655 fiber is typically 0.2 dB/km at 1550 nm, and the PMD parameter is less than 0.1 ps/sqrt(km). Both values are lower than that of G.652 fiber.