Multi-mode all Fiber Interferometer based on Fabry-Perot Multi-cavity and its Temperature Response

We present the use of conventional arc discharge technique for manufacturing an optical fiber Fabry-Perot interferometer using hollow core photonic crystal fiber and conventional single-mode fiber. The interferometric structure is composed by several intrinsic Fabry-Perot cavities, here the excitation of several fiber optic modes generates a high frequency interference reflection spectrum with special properties such as a free spectral range of 0.1 nm and visibility near to 6 dB. Thermal analysis has been conducted to demonstrate a sensing application, hence several modal Fabry-Perot interferometers were immersed in liquid and controlled temperature increments were applied. The thermal variations show a linear phase shifting to a shorter wavelength. The analysis exhibits a sensitivity and resolution of 27pm/°C and 0.7 °C respectively. The proposed fiber structure offers compactness, robustness, low-cost fabrication, simple manufacturing process and remote sensing operation. Moreover, it was demonstrated for real sensor applications: suitable sensitivity, good resolution, and long dynamic range.