Temperature-insensitive and intensity-modulated embedded photonic-crystal-fiber modal-interferometer-based microdisplacement sensor

We propose and demonstrate a temperature-insensitive and intensity-modulated embedded photonic-crystal-fiber (PCF) modal-interferometer-based microdisplacement sensor. The embedded PCF sensor has the structure of single-mode-fiber (SMF)–PCF–SMF, with a core offset at one splice joint. With the structure embedded in a cured carbon-fiber-composite-laminate-based simple-supported beam, the applied microdisplacement can be measured by monitoring its extinction ratio variation, while the extinction ratio variation is independent of the temperature variation and bending-induced strain. The sensitivity reaches 0.0024 dB/μm, the measurement resolution reaches 42 μm, and the dynamic measurement range is within the range of 0–200 Hz.