Highly sensitive optical refractometer based on edge-written ultra-long period fiber grating formed by periodic grooves

Abstract

An ultra-long-period fiber grating with periodic grooves structure (G-ULPFG) fabricated by using an edge-writing method with high frequency CO 2 laser pulses is reported, for the first time to our knowledge. The experimental results show that the different resonant peaks of the G-ULPFG have different temperature and refractive index sensitivities, and in particular, the refractive index sensitivity is much larger than that of conventional ULPFG due to the edge-groove structure. Such a G-ULPFG could be used as a highly sensitive optical refractometer with temperature self-compensation.