| 摘要 |
In a single mode fiber under test a direct measurement of transmissive dispersion, such as of colors or polarizations, is produced. In the measurement of chromatic dispersion, light is modulated in amplitude by a first, high frequency signal and between one wavelength and another by a second, low frequency signal. Light transmitted through a fiber under test is received by a photodetector providing an output which is compared to the high frequency reference for phase by a first phase-sensitive detector. The amplitude modulated output of the first phase-sensitive detector is compared by a second phase-sensitive detector, preferably a lock-in amplifier to the low frequency reference signal to provide a signal indicative of transmissive dispersion. Other forms of dispersion, including polarization dispersion, may be measured. A source is modulated at a first, high frequency. A second, low frequency signal is used to vary the light between the first transmissive parameter value and a second, namely a first polarization and a second polarization. The light is varied at the low frequency between two values of the independent variable with respect to which dispersion is measured.
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