| 摘要 |
PROBLEM TO BE SOLVED: To precisely measure a group delay time regardless of values of a modulation frequency. SOLUTION: In this method, a true group delay time is estimated from the group delay time actually measured by the following operations. 1) A group delay time ripple spectrum (see Fig. (a)) is obtained by reducing a linear component from the group delay time actually measured. 2) The group delay time ripple spectrum is Fourier-transformed by wavelengths (see Fig. (b)). 3) The group delay time ripple spectrum (Fourier-transformed spectrum), which is Fourier-transformed, is divided by an averaged factor spectrum (see Fig. (c)) (see Fig. (d)). 4) The Fourier-transformed spectrum, which is corrected, is inversely Fourier-transformed (see Fig. (e)). 5) The true group delay time is obtained by adding the linear component to the Fourier-transformed spectrum inversely Fourier-transformed.
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