| 摘要 |
To provide a technique for measuring characteristics such as chromatic dispersion and the like, by making it possible to continuously sweep the wavelength of light source. The present invention comprises a variable-wavelength light source 12 for generating a variable-wavelength light, wavelength of which is variable, having an identification waveform at the time when the wavelength is changin g, wherein the identification waveform is distinguishable from a normal wavefor m before and after the time when the wavelength is changing an optical modulat or 14 for modulating the variable-wavelength light to a predetermined frequency and casting it on an optical fiber 30; and an identification waveform detection section 24 for detecting the identification waveform in a light transmitted through the optical fiber 30, wherein since the time t0 that the identification waveform detection section 24 detects the identification waveform is the tim e when the waveform starts to change, it is possible to obtain a synchronizati on of incidence side and exit side of optical fiber 30 using the t0. Accordingly, it is possible to obtain the synchronization of incidence side and exit side of device-under-test even if the wavelength of light source is continuously swept, whereby characteristics such as chromatic dispersion and the like can be measured.
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