Patent ID: 7692849

Claim:
An optical amplifier provided with: an input port to which an optical signal is input; an output port to which an optical fiber is connected; an optical amplifying section disposed on an optical path between said input port and said output port; and a control section that controls said optical amplifying section, comprising: a test light supply section configured to supply, to said optical amplifying section, a test light corresponding to a wavelength of the optical signal input to said input port; an optical power measuring section configured to supply said test light amplified by said optical amplifying section to one end of said optical fiber from said output port, and configured to measure a power of a light which is input to said output port from the one end of said optical fiber and propagated in a direction opposite to that of said input light, to judge whether or not stimulated Brillouin scattering occurs; and a computing section configured to obtain a threshold of the input light power, at which the stimulated Brillouin scattering occurs in said optical fiber, based on the input light power and the judgment result in said optical power measuring section, and configured to obtain a relation between the input light power and an occurrence amount of a nonlinear optical effect which is different from the stimulated Brillouin scattering in said optical fiber, using said threshold, wherein said control section is configured to control an amplifying operation of the optical signal in said optical amplifying section, based on the relation obtained by said computing section, to suppress an occurrence of the nonlinear optical effect in said optical fiber.