Solutions of strain and temperature cross-sensitivity of long period fiber grating temperature sensing

Long period fiber grating is transmission spectrum grating,which is fiber core basic model coupling with cladding modes, and resonance wavelength and amplitude of long period fiber grating is very sensitive to the change of external environment, long period fiber grating has better sensing properties than traditional FBG in temperature, stress, bending, distortion, lateral load, refractive index, and so on. Because the long period fiber grating was sensitive to two or more parameters, when optical fiber grating for sensing measurement, it was difficult to distinguish the change of the measured caused by the various parameters respectively, and cross-sensitivity problem of long period fiber grating was more serious than that of the fiber Bragg grating. The cross-sensitivity was the key problem of fiber grating sensors. Based on analysis of the current typical ideas and solutions, one idea and solution of relation was proposed in this paper, and solves cross-sensitivity between stress and temperature in the long period fiber grating temperature sensing measurement. This idea makes full use of the cross-sensitivity phenomenon of the temperature and strain of LPFG and turns the negative interference of the strain on the temperature to positive sensitization.