A Robust, Multiplexable Fibre Sensor For Simulataneous Measurement of Bend and Strain

We report on the design and implementation of a novel optical fibre sensor for simultaneous measurement of bending and longitudinal strain. An all-fibre transducer is comprised of a fibre Bragg grating preceded by a short region of conventional fibre. Peak Bragg reflections experienced by orthogonal linearly polarised modes travelling within the sensor region shift identically with strain and temperature but oppositely with fibre bending. A novel switching interrogator allows isolation of the common mode strain signal to facilitate a robust measurement of both bend and strain while retaining the grating-based transducer's capability for serial multiplexing