Transverse strain sensing based on optical fibre Solc filter
We present an optical sensor based on Solc filter to measure the transverse strain. The Solc filter is made of highly birefringent fibre by twisting its optical axes back and forth in equal sections. When a polarised light goes through the sensor, a periodic transmission response is obtained with a certain free spectra range (FSR) determined by the modal birefringence and the section length. The transverse strain can be measured by the shift of FSR from the transmitted response as the transverse stress changes the birefringence. More importantly we find that the measurement of transverse strain is free from the influence of temperature. We theoretically analyse the sensor model and simulate it by Jones Formalism. It is found that the sensitivity can achieve 7.14pm/??. The influence of section length, wavelength of light source, modal birefringence and number of sections on the sensitivity is also investigated.
transverse strain optical fibre solc filter modal birefringence shift of the fsr polarisation maintaining fibre structural health monitoring