Ultra-wide range dual-parameter surface plasmon resonance sensor based on right-angled polishing photonic crystal fiber

Abstract Dual-parameter sensors are highly competitive and commercially valuable in industrial, medical, and biochemical fields. A two-parameter surface plasmon resonance (SPR) sensor with an ultra-wide measuring range is proposed, which can measure both refractive index (RI) and temperature (T). The sensor structure is a right-angle side-polished type, with Ag+Au deposited on one side-polished surface for RI measurement and Ag+Au+polydimethylsiloxane (PDMS) on the other side-polished surface for T measurement. The combination of the right-angle side polishing structure and the gold-silver composite film enables the sensor to have an extremely wide RI and T detection range. The wide measurement range not only meets the common liquid RI detection, but also enables the detection of substances with RI below 1.3333, such as halogenated ethers, fluorinated organic compounds and aerogels. The right-angle side polishing enables the SPR to be excited at a wider range of incidence angles, enabling the sensor to measure in a wider parameter range. The gold-silver composite film has the ability to widen the wavelength range and enhance the local electric field intensity, so that the sensor can detect substances with low RI. Gold film also prevents the silver layer from being degraded by the environment, increasing the service life of the sensor. The calculation results show that the sensor achieves a maximum RI sensitivity of 17900 nm RIU −1 (RI measurement range 1.20 ∼ 1.42) and a maximum T sensitivity of 12.8 nm °C −1 (T measurement range −10 °C ∼ 200 °C), and do not interfere with each other, a perfect solution to the crosstalk problem. In RI and T measurement, the sensor has a wide measuring range and good sensitivity, which makes it have a good prospect in environmental detection, biomedical and aerospace fields.