Birefringence measurement of optical fibers under various stress conditions

A novel method of birefringence measurement in highly birefringent elliptical-core and bow- tie fibers influenced by simultaneous action of various stress conditions such as those induced by hydrostatic pressure, longitudinal strain, temperature and twisting effect is presented. The method is based on twist-induced effects in HB fibers and has been successfully applied in a stress environment. The experiments were conducted using a specially designed pressure facility, which made it possible to simultaneously generate several mechanical perturbations, including twist and hydrostatic stress, and to investigate their effects on mode transmission in optical fibers. The results indicate that in the case of HB single-mode bow-tie fibers, hydrostatic pressure and also longitudinal axial strain increased polarization birefringence what closely confirms our birefringence measurement based on Rayleigh scattering.