Dispersion of group and phase modal birefringence in optical fibers measured by time-domain and spectral-domain tandem interferometry

Abstract

Two different measurement techniques based on tandem interferometry are used to measure the dispersion of group and phase modal birefringence in elliptical-core optical fibers. The first technique is based on time-domain tandem interferometry and uses processing of a series of interferograms at different wavelengths recorded in a tandem interferometer placed at the output of the optical fiber under test. The second technique is based on spectral-domain tandem interferometry and employs a low-resolution spectrometer. It uses a series of the spectral interferograms recorded at the output of a tandem configuration of a Michelson interferometer and the optical fiber under test to resolve the so-called equalization wavelengths, at which the overall group optical path difference is equal to zero. This technique enables the direct dispersion measurements of the group modal birefringence over a wide spectral range. The results obtained by both measurement methods are compared each other and good agreement is confirmed. We also modeled the dispersion of phase and group modal birefringence in the optical fibers using the modified perturbation approach first proposed by Kumar.