Patent ID: 6236452
Filing Date: 2001-05-22
Classification: G01M,H04B

Abstract:
An optical amplifier evaluation method comprising:modulating light output from a light source into a rectangular optical signal having predetermined ON and OFF periods by a first optical modulator;applying the optical signal modulated by said first optical modulator to an optical fiber amplifier to be evaluated;passing the optical signal output from said optical fiber amplifier to be evaluated through a second optical modulator only during a given period in the OFF period of the optical signal modulated by said first optical modulator, thereby measuring a light intensity P.sub.ASE of spontaneous emission in said optical fiber amplifier by a light intensity measurement device;obtaining an optical loss on an optical path extending from said optical fiber amplifier to said light intensity measurement device using output light from said optical fiber amplifier in a no-input state, and correcting, using the obtained optical loss, the light intensity P.sub.ASE of spontaneous emission in said optical fiber amplifier that is measured by said light intensity measurement device; andobtaining a noise figure NF of an optical signal in said optical fiber amplifier using a corrected light intensity P.sub.ASE ' of spontaneous emission in said optical fiber amplifier in accordance with the following equation:NF=P.sub.ASE '/(h.multidot..nu..multidot.G.multidot..DELTA..nu.)whereh: Planck's constant.nu.: light frequency of input optical signalG: gain.DELTA..nu.: measurement frequency resolving power width (measurement frequency width) of said light intensity measurement device.