Determination of the differential mode delay of a multimode 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 are used to obtain the intermodal interference signal in spectral domain after light passes an MMF. The MMF is used as a common path interferometer by itself without using any reference arm in an interferometer. Instead of using an offset launching technique, we present an effective method to obtain all available intermodal interference signals at a single shot by using a mode scrambler. The measured results using the proposed method are compared with those obtained using a conventional time-domain DMD measurement method. (c) 2006 Optical Society of America