All-fiber interferometric technique for estimating the mode effective index of a single-mode fiber

An all-fiber interferometric experimental technique to determine the mode effective index n(eff) of a single-mode fiber is proposed. The method involves setting up an unbalanced Mach-Zehnder interferometer (MZI) with the test fiber. By inducing a small change in the differential path length between the two arms of the MZI, a proportional change in the periodicity of its transmission spectrum could be introduced. A precise measurement of this change in periodicity has been used to accurately determine the value of n(eff) of the test fiber. (c) 2006 Society of Photo-Optical Instrumentation Engineers.