SPECTRUM SPREAD COMPENSATION UNIT AND OPTICAL TRANSMISSION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a spectrum spread compensation unit where the wavelength dependency of a loss is reduced. SOLUTION: A spectrum spread compensation unit reduces spread spectrum in the 1.55 μm wavelength band of an optical fiber transmission line. A bobbin 10 having the barrel diameter of not more than 150 mm and an optical fiber coil 18 where spread spectrum compensation optical fibers 16 having spread spectrum whose code is inverse to the optical fiber transmission line and having spread spectrum inclination whose code is inverse to the optical fiber transmission line is bent and rewound to the barrel 12 of the bobbin 10 are installed. The ratio of a difference between the maximum value and the minimum value of a transmission loss in the wavelength of 1530 nm-1560 nm against a spread value in the wavelength 1550 nm is not more than 4×10<-4> dB/ps/nm. Since a bending loss owing to bending becomes larger on the side of the longer wavelength, the change of the transmission loss owing to Rayleigh scattering appearing on a short wavelength side is compensated by a change by the bending loss.