Tuned Pressure Sensitivity of Dual Resonant Long-Period Gratings Written in Boron Co-Doped Optical Fiber

This paper presents a pressure sensor based on a long-period grating (LPG) written in boron co-doped photosensitive fiber and operating at the phase-matching turning point. It is shown that the pressure sensitivity can be tuned by varying the UV exposure time during the LPG fabrication process as well as by varying ambient temperature during pressure measurements. The achieved pressure sensitivity in certain pressure range can reach over 1 nm·bar^{- 1}, and is at least four times higher than for previously presented gratings working away from the double-resonance regime. In terms of an intensity-based measurement, the sensitivity at the turning point can reach 0.212 dB ·bar ^{- 1}.