Low-Pressure Sensor Realized With 8-Shaped Birefringent Optical Fiber

This study presents an innovative approach to pressure sensing by utilizing an 8-shaped birefringent optical fiber fabricated through a mechanical milling technique. The proposed sensor employs the Sagnac effect to monitor wavelength shifts in the interference pattern. Experimental results demonstrate that the sensor achieves a high sensitivity of 441 pm/kPa within the pressure range of 0 to 20 kPa, enabling accurate pressure measurements with a resolution of up to 2 Pa. The measurements exhibit good repeatability, and demonstrate a linearity of 99.65%. In addition, by integrating a fiber Bragg grating fabricated using a femtosecond laser into the 8-shaped fiber within the Sagnac loop, the temperature cross-sensitivity was determined to be 20 Pa/ °C. The combination of the 8-shaped birefringent fiber and the Sagnac interferometric technique offers a promising solution for achieving precise and reliable pressure sensing in low-pressure environments.