Broad spectral range measurements and modelling of birefringence dispersion in two-mode elliptical-core fibres

Abstract

We present the results of measurement and modelling of the birefringence dispersion in elliptical-core fibres (ECFs). The measurement is performed over a broad wavelength range (e.g. 450–1450 nm) by two spectral interferometric techniques. First, a technique employing a tandem configuration of a Michelson interferometer and an ECF under test is used for a broad spectral range measurement of the group modal birefringence for two spatial modes supported by the fibre. Second, a method with a lateral point-like force acting on the fibre and based on spectral interferometry is used for measuring the phase modal birefringence at one wavelength for the fundamental mode only. The measured value is combined with the dispersion of the group modal birefringence to obtain the phase modal birefringence over a broad wavelength range. We also modelled the dispersion characteristics taking into account contributions of both the elliptical shape of the core and the residual thermal stress. The dispersion characteristics measured for the three ECFs show very good agreement with the results of numerical modelling.