Simultaneous measurement of temperature and refractive index based on PCF–SPR sensor

Abstract A compact surface plasmon resonance (SPR) sensor has been proposed and theoretically analyzed based on a photonic crystal fiber (PCF) for the simultaneous measurement of refractive index (RI) and temperature. Unlike conventional PCFs, the two deep grooves are polished to enhance the interactions between the fiber core mode and the surrounding medium, with the improvement of fiber optic sensitivity. Silver films are deposited on both the grooves to excite the SPRs. Furthermore, polydimethylsiloxane (PDMS) is covered in a groove to sense the temperature variation, whereas another groove directly interacts with the surrounding medium to realize RI sensing. Due to the flexible structure design, the effective RI of the fiber core mode can be tuned conveniently to equate the RIs of plasmonic modes, thus realizing hybrid modes with profiles both in the fiber core region and in the two grooves. The hybrid mode in the PDMS layer can only sense the temperature with a sensitivity of up to −4.6 nm °C −1 . Another hybrid mode with plasmonic mode in the second groove only responds to the surrounding RI with a sensitivity of up to 2760 nm RIU −1 . Therefore, RI and temperature sensing can be realized simultaneously via this compact PCF–SPR sensor.