In-series singlemode thin-core diameter fibres for simultaneous temperature and strain measurement

A fibre optic sensor capable of simultaneous measurement of temperature and strain is proposed and experimentally demonstrated. The sensor head is formed by cascading two sections of singlemode thin-core diameter fibres (TCFs) that act as two different inter-modal interferometers (IMIs). Owing to the different sensitivity responses of the two IMIs to strain and temperature, it is possible to simultaneously measure temperature and strain by monitoring the resonant wavelength shifts of the IMIs. This type of sensor is easy to fabricate, compact, has high sensitivity and low cost, and it exhibits great potential in dual-parameter measurement.