Drift-eliminating method of intensity demodulation on a chirped fiber grating strain sensor

It is quite possible to detect the strain of a sample based on a chirped fiber grating (CFG) sensor, which has a wider bandwidth of light signal than a fiber Bragg grating. Usually, environmental factors play negative roles in the process of intensity demodulation. A drift-eliminating method of CFG intensity demodulation has been created and tested in our lab. Three CFG sensors were involved in this research. Two of them with close wavelength bands connected in series were used as a strain sensing unit; the third one was used as a referencing grating working within the reflective wavelength spectrum of the other two. It is shown that the signal ratio of the sensing unit and the referencing grating is a linear function of the loading strain. The linearity is as high as 99.79%.