OPTICAL AMPLIFIER AND OPTICAL TRANSMISSION SYSTEM USING THE SAME

摘要

PROBLEM TO BE SOLVED: To obtain a concentrated constant type optical amplifier with a flat and wide gain band by using a highly nonlinear optical fiber or dispersion compensation fiber as a Raman amplification medium. SOLUTION: The optical amplifier A comprises a Raman amplification section A1 and a rare earth added fiber amplification section A2 . The Raman amplification section A1 comprises the highly nonlinear optical fiber a1 which is the Raman amplification medium, an exciting light source a2 to generate the exciting light for exciting the highly nonlinear optical fiber a1 and a multiplexer a3 . This multiplexer a3 makes the exciting light incident on the highly nonlinear optical fiber a1 from the direction opposite to the incident direction of the optical signal and outputs the optical signal amplified by the highly nonlinear optical fiber a1 to the rare earth added fiber amplification section A2 . The Raman gain of the Raman amplification section A1 is adjusted to offset the decrease of the gain spectra in the long wavelength region in the rare earth added fiber amplification section A2 of such constitution, by which the wavelength region in which the gain is flat over a wide band is obtd.