METHOD OF AND APPARATUS FOR MEASURING POLARIZATION BEAT LENGTH IN HIGHLY BIREFRINGENT SINGLE MODE OPTICAL FIBRES

摘要

In the measurement of beat length in a highly birefringent single mode optical fibre, a constant force perpendicular to the fibre axis is applied to the fibre and is displaced incrementally along the fibre axis. The state of polarization of radiation leaving from the fibre is determined at each increment and beat length values are obtained from both the amplitude ratio of and the phase difference between the components, along the two birefringence axes, of the electrical field associated with radiation launched into the fibre.