Intensity-modulated micro-displacement sensor with an embedded fiber dual cladding modes interferometer

We propose a novel fiber micro-displacement sensor based on an embedded fiber dual cladding modes interferometer. This type of interferometer has a very high extinction ratio (ER) of 27.7 dB, with only one very deep resonance dip within C and L bands, enabling it to be used as an intensity-modulated sensor. With it embedded in a cured carbon fiber composites based beam, it shows a high sensitivity response to micro-displacement in ER variation. Experimental results show that there is a quasi-linear relationship between the micro-displacement and its ER variation, with the measurement resolution of 4.67 μm, and the dynamic measurement range of 0∼200 Hz.