Transverse load sensing with a tilted fiber Bragg grating compressed between conforming elastomers

A novel fiber optic transverse load sensor is experimentally demonstrated by using a 10° tilted fiber Bragg grating (TFBG) compressed between two conforming elastomer layers, which has a high refractive index and low Young's modulus. The applied transverse loads increase the contact angle of optical fiber and conforming elastomers, which suppress the cladding modes coupling and introduce a broadband loss in the spectrum of the TFBG. Using fast Fourier transform (FFT) analysis on a selected bandwidth of the transmission spectrum, it is found that the peak amplitude of the dominant spectral fringes decreases with the increasing transverse load with an near-linear sensitivity of 125 arbitrary unit/N (in the range of 0~6N). Finally, the temperature effect on the response of sensor has been investigated at a constant load of 3.8 N. The results show that the sensor is independent to temperature, with a maximum error of 2% from 25°C to 75°C.

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