Sensing characteristics of long-period fiber grating based on chiral micro-taper structure of eccentric fiber

A long-period fiber grating (LPFG) based on chiral micro-taper structure was proposed. The chiral micro-taper structure was fabricated on the eccentric optical fiber through arc discharge technology, and its introduction significantly enhanced the performance of the sensor, which not only greatly improved its torsional sensitivity, but also enabled the sensor to have the ability to identify the torsional direction. To deeply explore the sensing characteristics of this chiral micro-taper structure long-period fiber grating, a method combining simulation and experiments was adopted. The research results show that the proposed sensor has the ability of direction discrimination, and its sensitivity is as high as 592.1 pm/(rad·m⁻¹). Compared with long-period fiber gratings without chiral structures, it not only has the function of direction discrimination, but also its sensitivity is increased by nearly three times. This sensor features small size, simple preparation and high sensitivity, and has broad application prospects in fields such as health monitoring and precise measurement.