| 摘要 |
PURPOSE:To make possible simple measurement with high accuracy by making incident the light signal subjected to intensity modulation and wavelength modulation on an optical fiber to be measured from one end thereof and measuring the max. phase shift or max. frequency shift of the phase modulation component of the exit light from the other end. CONSTITUTION:A measuring instrument is constituted of a light source 1 consisting of an LED, an intensity modulating circuit 4, a wavelength modulator 5, lenses 6, 8, the optical fiber 7 to be measured, a photoelectric converter 9 and a spectrum analyzer 11, etc. After the length L of the fiber 7 is measured, the light subjected to the simultaneous double modulations, i.e., the intensity modulation of a modulating angle frequency omegac and wavelength modulation of a modulating angle frequency omegam, central wavelength lambda and wavelength amplitude DELTAlambda is made incident on said fiber from one end thereof. The max. phase shift beta of the phase modulation component of the exit light from the other end is measured and the absolute value ¦D¦ of the wavelength dispersion value is calculated by the equation ¦D¦=beta/L.DELTAlambda.omegac, by which the easy measurement of the wavelength dispersion of the fiber 7 over the wide wavelength region with high accuracy is made possible. |
