Group velocity dispersion measurement method using sinusoidally phase-modulated continuous wave light based on cyclic nature of optical waveform change by group velocity dispersion

We show that any optical pulse train recovers its original waveform after passing through a group velocity dispersion (GVD) device when the total GVD value of the device is equal to an integral multiple of 1/(2πfrep 2), where frep is the repetition rate of the optical pulse train. In addition, we detail our proposed GVD measurement method, or optical phase-modulation (PM) method, which utilizes a sinusoidally PM continuous wave (CW) light as a probe light. The total GVD B2 of a device under test (DUT) is derived by using a very simple equation, |B2|=1/(2πfnull 2), where fnull is the smallest modulation frequency at which the sinusoidally PM light becomes CW light again after passing through the DUT.