Double Cladding Fiber Chiral Long-Period Grating-Based Directional Torsion Sensor

Abstract

We demonstrated the fabrication of a chiral long-period fiber grating (CLPG) by CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -laser heating of a twisted double-cladding fiber (DCF). The polarization and sensing characteristics of the DCF-CLPG are investigated experimentally. Due to the helical structure, the grating shows a higher torsion sensitivity of -0.40 nm/(rad/m), and the torsion rate and torsion directions can be measured simultaneously using single DCF-CLPG. The temperature, strain, bending, and surrounding refractive index sensing characteristics are also investigated experimentally. The proposed CLPG has a promising application as high-sensitivity directional torsion sensor.