A biocompatible and robust fiber surface plasmon resonance (SPR) temperature sensor was fabricated based on an alcohol-filled hollow-core fiber. The fabrication process of this designed sensor included Ag film coating, liquid injection and fusion splicing, which was low-cost and efficient. Due to the high refractive index sensitivity of SPR effect and the high thermal optical coefficient of alcohol, the designed sensor performed well in temperature sensing, whose linear sensitivity reached as high as 1.16 nm/°C in the range of 35.5 °C ~ 70.1 °C. Being small in size, low in fabrication cost and highly sensitive in performance, this sensor is suitable for temperature detection during biological and chemical reactions, and has the potential to realizing multi-parameter or distributed temperature measurement.

We propose a dual-channel surface plasmon resonance (SPR) sensor based on hollow-core fiber (HCF) for the simultaneous measurement of the liquid refractive index (RI) and ambient temperature. The simultaneous monitoring of two parameters can effectively realize the temperature compensation of liquid RI measurement. One channel is coated with a silver film to sense the liquid RI, the other channel is coated with a gold film and polydimethylsiloxane (PDMS) to sense the ambient temperature, and the cross sensitivity of the multi-parameter measurement is solved using the dual-wavelength matrix method. The sensing performance of the proposed sensor is investigated both theoretically and experimentally, which proves that it can achieve high sensitivity in a relatively wide measurement range. The experiment shows that the liquid RI sensitivity is as high as 2400.079 nm/RIU in the RI range of 1.3333–1.3770, and the temperature sensitivity is −1.29 nm/°C in the temperature range of 40 °C–90 °C. This work provides a new scheme for the multi-parameter measurement, and the proposed sensor has the advantages of simple and compact structure, low cost, wide measurement range and high sensitivity, which promises broad application prospects in the simultaneous monitoring of liquid RI and temperature.

In this work, a new method was explored for developing temperature and relative humidity (RH) optical fiber sensors based on surface plasmon resonance (SPR). A SPR optical fiber sensor coated with carboxymethyl cellulose (CMC) and polydimethylsiloxane (PDMS) was proposed for the simultaneous measurement of RH and temperature. The sensor was fabricated by connecting two no-core optical fibers (NCFs) using multimode optical fibers (MMFs). Metal films were deposited on the surface of NCFs and further coated with CMC and PDMS. CMC coating was used for RH sensing based on the change of refractive index (RI) caused by water absorption; PDMS coating was used for temperature sensing based on its RI change with temperature. Univariate analysis showed that there was very weak interaction between RH and temperature measurement. For RH sensing, the sensitivities were −1.230 nm/RH%, −2.932 nm/RH% and −0.431 nm/RH% when RH were 50%~65%, 65%~70% and 70%~80%, respectively; for temperature sensing, the sensitivity was −2.213 nm/°C at 10 °C~50 °C. The proposed sensor can not only respond to both temperature and RH variation, but also compensate the cross sensitivity between the two parameters. It is simple in structure, easy to manufacture and efficient in the simultaneous detection of temperature and RH, which promises great application prospects in the fields of agriculture, food industry, biological field and other production activities.

Multi parameter measurement and device miniaturization are the development trend of optical fiber sensors. Here we propose a compact dual channel surface plasmon resonance (SPR) fiber sensor which can measure the liquid refractive index (RI) and ambient temperature in real time. This sensor coats metal and polydimethylsiloxane (PDMS) on the side of a no-core D-shaped fiber: the channel for measuring the liquid RI is covered by silver film, and the channel for temperature sensing is covered by gold film and PDMS. The sensing sensitivity is analyzed by finite element method. When the liquid RI is within 1.33~1.44 and the temperature is within 0~180 °C, the corresponding maximum spectral sensitivity is 12530 nm/RIU and -3.465 nm/°C, respectively. The sensor has wide detection range, compact structure and temperature compensation function, which is suitable for environmental monitoring and high-precision sensing.

A refractive index sensor based on dual-core photonic crystal fiber (PCF) with hexagonal lattice is proposed. The effects of geometrical parameters of the PCF on performances of the sensor are investigated by using the finite element method (FEM). Two fiber cores are separated by two air holes filled with the analyte whose refractive index is in the range of 1.33–1.41. Numerical simulation results show that the highest sensitivity can be up to 22,983 nm/RIU(refractive index unit) when the analyte refractive index is 1.41. The lowest sensitivity can reach to 21,679 nm/RIU when the analyte refractive index is 1.33. The sensor we proposed has significant advantages in the field of biomolecule detection as it provides a wide-range of detection with high sensitivity.