OPTICAL AMPLIFIER SYSTEM

PROBLEM TO BE SOLVED: To obtain an optical amplifier system that makes an optical output level constant and can control a gain gradient, without the need for provision of pre-emphasis in the amplification of a wavelength-multiplexed light and causing other problems of losing the reliability of a compensation unit and of increasing the system cost. SOLUTION: The optical amplifier system is provided with an optical amplifier 3 that amplifies an input signal light, an output detection means 5 that detects an output level of the optical amplifier, an output control means 6 that controls the output level of the optical amplifier depending on an output level detected by the output detection means 5, a gain gradient detection means 7 that detects the gain gradient with respect to the wavelength of the optical amplifier, and a gain gradient control means 8 that controls the gain gradient of the optical amplifier 3, in response to the gain gradient detected by the gain gradient detection means 7.