Simultaneous twist and pressure effects in highly birefringent single-mode bow-tie fibers

The authors present the results of birefringence measurements in highly birefringent optical bow-tie fibers under hydrostatic pressure up to 100 MPa. The birefringence measurement method is based on twist-induced effects and has never before been applied in a high-pressure 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. A comparison with theoretical results as well as with previous experimental data on pressure influence on the beat length parameter in highly birefringent fibers is provided.