Study on long period fiber grating sensor based on deep-grooved process

A high-sensitivity strain sensor of LPFG based on deep-grooved process was investigated. The LPFG was fabricated by a high frequency focused CO2 laser irradiation system in ways of periodic spaced heating on the ordinary single-mode fiber. Combined with a high precision position controller and optical measurement platform, an optical fiber strain sensor measurement platform was established. A theoretical analysis based on coupled mode theory and transmission matrix method for parameter design and optimization of LPFGs was adopted. Experimental results demonstrated that the axial strain sensitivity of a LPFG strain sensor would be increased with the increase of groove depth of the grating, and such a deep-grooved LPFG strain sensor would have an axial strain sensitivity up to -10.28pm/με which should be much larger than the strain sensor without grooves on one side of fiber grating. Therefore, this novel sensor should be able to find a potential value in the field of sensor applications.