Integrated Fiber-Optic Salinity and Temperature Sensor Based on Hybrid Dual Microcavity

In this article, a novel hybrid-dual-microcavity (h-DMC) structure is proposed for the first time in order to achieve simultaneous salinity and temperature measurement with high sensitivity and high discrimination. The h-DMC structure is completed by proper arc-discharged large lateral -offset splicing and fulfilling the temperature sensitive polymer. Based on the shared cladding, two parallel microcavity Mach-Zehnder interferometers are formed and, respectively, used to monitor the salinity and temperature variations of solution. The obtained superimposed transmission spectra are easily decoupled and precisely reconstructed due to the obvious spatial frequency difference. The average sensitivities of h-DMC can reach -2.34 nm/‰ and 5.26 nm/°C with high linearity and low measured errors, which correspond to the detection limit of 0.0085‰ and 0.0038 °C, respectively. Due to the merits of low cost and high yield, such an integrated fiber-optic dual-parameter sensor is very competitive and promising to high-precision marine environment monitoring.