Constructed fiber-optic FPI-based multi-parameters sensor for simultaneous measurement of pressure and temperature, refractive index and temperature

In paper, a multi-parameter measurement sensor based on single-mode fiber and ultra violet (UV) curable adhesive is proposed and fabricated for simultaneously distinguish gas temperature and pressure, liquid refractive index (RI) and temperature. The proposed sensor consists of a fiber Bragg grating (FBG) and three Fabry-Pérot interferometers (FPIs) that are fabricated from a tiny segment of single-mode fiber, a section of UV curable adhesive and their integrations. The whole size of experimental sensor is below 1 mm since the combinations of micro-cavity. Interrogation of the sensor utilized Fourier band-pass filter (FBPF) and fast Fourier transform (FFT) signal processing of the reflection spectrum, allows for free extraction of individual cavity resonators’ frequency. Results show that the sensor not only has four different temperature response sensitivities, but also has higher resolutions as it is used in simultaneous distinguishing measurement of pressure and temperature, refractive index and temperature. The maximum resolutions of temperature, pressure and liquid RI are 0.07 °C, 6 × 10−3 MPa and 3 × 10−4 RIU, respectively. The sensor might be applied to distinguish physical parameters related to gas or liquid environment, and work in complex environments such as high pressure.