Method and device for measuring a noise figure in optical amplifiers

摘要

A method and device for automatically and accurately measuring a noise figure of an optical amplifier are disclosed. In the method, light pulses which have different wavelengths lambda 1 DIFFERENCE lambda n and have a period shorter than a time constant of extinction of the optical amplifier are generated. The light pulses thus generate are supplied to the optical amplifier. Powers PAMP1 DIFFERENCE PAMPn of amplified lights outputted from the optical amplifier which correspond to the light pulses and have the wavelength lambda 1 DIFFERENCE lambda n and powers PASE1 DIFFERENCE PASEn of lights which have the wavelength lambda 1 DIFFERENCE lambda n and are outputted from the optical amplifier when the amplified lights are not outputted from the optical amplifier are measured. Noise figures NF1 DIFFERENCE NFn at the wavelengths lambda 1 DIFFERENCE lambda n the optical amplifier are calculated according to the following equation.NFk=(PASEk/h nu kGkBo)+(1/Gk)(k=1 DIFFERENCE n)In the above equation, h is Planck's constant; nu k(k=1 DIFFERENCE n) are light frequencies of the light pulses; Gk(k=1 DIFFERENCE n) are gains at the wavelengths lambda k(k=1 DIFFERENCE n) of the optical amplifier; and Bo is a band width of a pass band of an instrument which is used for measuring the power PASE1 DIFFERENCE PASEn.