Research on temperature sensing characteristics of fiber side-open cavity structure

• A novel sensing probe combined with fiber side-open cavity structure and PDMS is proposed. • It could achieve a high temperature sensitivity up to 12.32 nm/°C with the resolution of 0.0016 °C. • It could be in compact size of micrometer-level sensing length. A sensing probe based on fiber side-open cavity structure is proposed for the measurement of seawater temperature, which is mainly composed of a lead-in single mode fiber (SMF), a side-open cavity C-type microstructure fiber (SOCTF), a multimode fiber (MMF), a lead-out SMF, and a layer of polydimethylsiloxane (PDMS). It could effectively reduce the transmission loss, and promote the temperature sensitivity, with a micron-level sensing area. The relative simulations and experiments were carried out to verify the feasibility. The sensitivity could be up to 12.32 nm/°C with a temperature resolution of 0.0016 °C. Considering comprehensively, the sensing structure proposed in this paper could provide an effective measurement method for seawater temperature measurement.