| 摘要 |
PURPOSE:To easily obtain the measured value of high accuracy by measuring both the wavelength, in which the group delay time difference between the modes LP01 and LP11 to be transmitted through an optical fiber to be measured is reduced to zero, and the braking wavelength of the mode LP11. CONSTITUTION:The light of a multi-spectrum light source is fed through a spectrometer so that the wavelength of an output light is continuously varied. The resultant light is subjected to frequency sweeping treatment for each wavelength by a modulator 3 so that it is guided into an optical fiber 5 to be measured. The transmitted light is converted by a detector 6 and a light receiver 7 into a demodulated signal so that the frequency characteristics are measured by an spectrum analyzer 10 and an arithmetic device 11. Incidentally, the pulse waveform, which is formed by guiding the output light of a light source of variable wavelength as a single pulse into the optical fiber so that it is transmitted, may be analyzed. If the value of f 1/2DELTAtau is determined by the frequency sweeping operation, the delay time DELTAtau can be determined by a simple calculation so that the pulse waveform analysis need not be required. Thus, it is possible to easily determined the measured value of high accuracy. |
