Parallel Polished Plastic Optical Fiber-Based SPR Sensor for Simultaneous Measurement of RI and Temperature

In this work, a parallel polished plastic optical fiber (POF)-based surface plasmon resonance (SPR) sensor is proposed and demonstrated for simultaneous measurement of refractive index (RI) and temperature. The sensor is fabricated by double polishing the POF symmetrically and depositing a layer of gold film on both sides of the polished regions. By coating the polydimethylsiloxane (PDMS) layer on one of the polished sides, another resonance peak for the temperature sensing can be observed in the transmission spectrum. When the RI and temperature vary, the two resonance peaks will change, and the RI and temperature could be measured simultaneously by monitoring the wavelength shifts of the two peaks. Experimental results show that the sensor has an RI sensitivity of 1174 nm/RIU in the RI range of 1.335–1.37 and a temperature sensitivity of −0.7 nm/°C in the temperature range of 30 °C–80 °C. In addition, the results show that the crosstalk between the two sensing channels of the proposed sensor is negligible. The parallel polished structure is helpful to develop the multiparameter measurement sensors, which has potential application prospects in the biochemical sensing fields.