A novel optical fiber sensor based on surface plasmon resonance phenomenon that can be used for liquid temperature testing around the sensing probe is presented. According to the attribute of liquid refractive index decreasing with the rise of liquid temperature, a series of SPR spectrum curves, corresponding to temperature range from 10 °C to 90 °C, can be obtained from spectrum signal processing. The range of temperature testing can be adjusted by choosing liquids with different boil and refractive index as environmental medium. This paper analyzes theoretically the influence of a variety of liquid temperature on the metal film coated onto the sensing probe surface and the refractive index of fiber core. A real-time double-parameter testing involving resonance wavelength and the lowest light intensity reflectivity is also proposed. Moreover, the proportion concentration of mixed solutions with different refractive indices ranging from 1.3675 to 1.4281 refractive index units, including ethanol and glycol, is investigated utilizing relative spectrum measurement technology. The preliminary experiments confirm the feasibility of the optical fiber SPR sensor based on wavelength-interrogation for temperature and refractive index measurement.
Surface Plasmon Wave Sensor (SPWS) is a new type of sensor. Many output light measurements of SPWS exist, such as to measure the single color light intensity, to measure the absolute light intensity spectral and to measure relative light intensity spectral. In the paper, several ways to measure and analyze the outputs light of the SPWS are presented. In particular, absolute light intensity spectral analysis and relative light intensity spectral analysis are contrasted. For the way to measure the absolute light intensity spectral, it requests that the input light must be an ideal white light and has very steady light intensity. For the latter way, it needs not the same requests as the former. So the input light has little influence on the measurement and the relative light intensity spectral has much merit such as the low request to input light, higher precision etc. At last, we obtain a conclusion that it is most adaptable to use relative light intensity spectral analysis to measure the output light of the optic fiber SPWS.