Simple method for differential mode delay of a multimode optical fiber using Fourier-domain intermodal interference analysis

We present a novel differential mode delay (DMD) measurement method for a multimode optical fiber (MMF) based on Fourier-domain low-coherence interferometry (fLCI) for the first time. An optical spectrum analyzer and a mode scrambler were used to obtain intermodal interference signal in spectral-domain after light pass an MMF. The MMF was used as a common path interferometer by itself without using any reference arm in an interferometer. Our proposed method can measure a short or long optical multimode fiber simply, accurately, and rapidly.