Investigation of the dispersion of multimode dielectric waveguides by the optical heterodyne method

A method for investigating intermode dispersion in multimode optical waveguides, based on optical heterodyning with rapid scanning of the source frequency, is proposed and analyzed. A temporal resolution of the order of 10^–9 sec was achieved experimentally using a photodetecting device having a response time of no better than 10^–5 sec. It is shown that this method is suitable for investigations not only of the dispersion, but also of the energy characteristics of waveguides.