Pressure sensitivity of the birefringent photonic crystal fiber with triple defect

Abstract

We investigated theoretically and experimentally an impact of hydrostatic pressure on phase modal birefringence in birefringent photonic crystal holey fiber of new construction. The birefringence in this fiber is induced by highly elliptical shape of the core, which consists of triple defect in the hexagonal structure. Using finite element method, we first calculated the stress components and deformations induced by hydrostatic pressure in the fiber cross-section. In the second step, the distribution of the stress-related corrections of refractive index were determined. Finally, we calculated the sensitivity of the phase modal birefringence (dB/dp) to hydrostatic pressure versus wavelength. The contribution of the geometrical effects related only to deformation of the holey structure as well as the stress-related contribution to the overall pressure sensitivities were analyzed separately. Our results show that these two factors decrease the phase modal birefringence, which results in negative sign of dB/dp. We also measured the pressure sensitivity for several wavelengths using polarimetric technique. The experimental and theoretical values of dB/dp show very good agreement.