Phase sensitivity of fundamental mode of hollowcore photonic bandgap fiber to internal gas pressure

The response of the commercial HC-1550-02 hollow-core photonic bandgap fiber (HC-PBF) to gas pressure applied internally to the hollow-core was experimentally investigated. The transmission spectrum of the HC-PBF was hardly affected by the pressure, while the accumulated phase of the fundamental optical mode showed a normalized pressure sensitivity of 1.044 × 10?2rad/(Pam), which is over two orders of magnitude higher than that to the external pressure. Numerical simulation showed that the observed high sensitivity to pressure is due to the pressureinduced refractive index change of air inside the hollow-core. This research could find potential applications in high sensitivity static and dynamic pressure measurement and optical phase manipulation.