Basic study of temperature independent fiber bending sensor for catheters using multicore fiber Bragg grating and two-photon absorption process in Si-APD

We propose temperature independent fiber bending sensor for catheters, which uses a multicore fiber with a Bragg grating inscribed in each core and spectral measurement technique based on intensity correlation of optical signals based on two-photon absorption process in a silicon avalanche photodiode. Although fiber Bragg gratings are generally sensitive to temperature change, the effect can be suppressed by processing the spectral data of reflected light from all the Bragg gratings, which was confirmed by the proof-of-concept experiment, where we successfully measured the same curvature for different temperature of 20, 25, 30, 35 and 40 degrees Celsius.