DIFFERENTIAL MODE DELAY MEASUREMENT SYSTEM FOR A MULTIMODE FIBER BY USE OF AN INTERMODAL INTERFEROMETER AND OPTICAL FREQUENCY CHIRPING

摘要

A differential mode delay measurement system for an MMF(Multimode Optical Fiber) using an intermodal interference with varied optical frequency is provided to easily increase resolving power due to the characteristic of an OFDR(Optical Frequency Domain Reflectometer) using a wavelength variable laser, and to overcome the limit of measurement length by measuring the light although the intensity of the light is low. A differential mode delay measurement system for an MMF(30) using an intermodal interference with varied optical frequency is composed of a wavelength variable laser(10) oscillating the laser light having the wavelength repeatedly varied in a linear form within a specific frequency band; a mode scrambler(20) installed at the front end of the MMF, to generate all available modes by transmitting the laser light oscillated from the wavelength variable laser to the MMF; an optical detector(40) detecting the light after converting the light passing through the MMF into the parallel light; and a delayed time calculating unit computing the delayed time between the modes by using an interference signal generated from the optical detector, and calculating a DMD(Differential Mode Delay) value from the delayed time between the modes.