Fabrication and sensing characteristics of helical long-period fiber gratings written in the rotated fiber by CO2laser

Abstract

A helical long-period grating (HLPG) was fabricated by twisting a conventional single-mode fiber when CO 2 laser beam was sweeping along the fiber axis. A grating with a contrast of 20 dB can be written in the fiber with a length of 1 cm. The spectral and sensing characteristics were investigated experimentally. The maximum sensitivity to surrounding refractive index and temperature measurement was measured to be 995 nm/RIU and 53 pm/°C, respectively.