Strain measurement based on fixed wavelength transmission of tapered long-period fiber grating

This paper studies the relationship between transmission intensity and strain based on tapered long-period fiber grating at a fixed wavelength. In experiments, tapered long-period fiber grating was prepared by the electric melting method. Experimental results show that two resonance peaks ap-peared at 1482 and 1537 nm, respectively. Here is the elaboration of the relationship between the resonant wavelength and the strain, its wavelength-strain sensitivity is 20 pm/mu epsilon, and the linearity was negative. Then our next study was about the relationship between transmission intensity and strain at a fixed wavelength. The results show that the transmission intensity at a fixed wavelength is related to the exponent with strain. The coupled-mode theory is applied to simulate the relation-ship between fixed wavelength and strain. The simulation results matched the experimental results. Two fixed wavelength transmission intensity ratio was used, and the ratio showed a linear rela-tionship with the strain, and the slope is -0.018 dB/mu epsilon. Therefore, within the 0.01% resolution of our detector, we could resolve a 0.16 mu epsilon strain change. We can select the appropriate light source and detector to achieve higher measurement accuracy. Thus, there is a great potential in fiber grat-ing strain sensors.