We present a new multimode dispersion measurement technique based on the time-of-flight method. The modal delay and group velocity dispersion of all excited modes in a few-mode fiber can be measured simultaneously by a tunable pulsed laser and a high speed sampling oscilloscope. A newly designed higher-order-mode fiber with large anomalous dispersion in the LP02 mode has been characterized using this method, and experimental results are in good agreement with the designed dispersion values. The demonstrated technique is significantly simpler to implement than the existing frequency-domain or interferometry-based methods.
Cheng, J., Pedersen, M. E. V., Wang, K., Xu, C., Grüner-Nielsen, L. E., & Jakobsen, D. (2012). Time-domain multimode dispersion measurement in a higher-order-mode fiber. Optics letters., 37(3), 347-349. https://doi.org/10.1364/OL.37.000347