Design of refractive index sensing based on optimum combination of plasmonic materials gold with indium tin oxide/titanium dioxide

Abstract. In this research work, a penta core photonic crystal fiber (PCF)-based refractive index (RI) sensor is presented to address the surface plasmon resonance (SPR) phenomenon. The proposed RI sensor (PRIS) model is tested with two material configurations, i.e., gold-indium tin oxide (Au–ITO) and gold–titanium dioxide (Au–TiO2). Analytes having an RI varying from 1.340 to 1.380 RIU are tested from the PRIS for both material configurations. These configurations are compared with each other based on sensor parameters, such as wavelength sensitivity (WS), amplitude sensitivity (AS), linearity, and sensor resolution (SR). The sensor parameters are investigated for both transverse electric (TM) mode and transverse electric (TE) mode. The proposed sensor with Au–ITO configuration offers a maximum WS of 12,000  nm  /  RIU, AS of 13,640  RIU  −  1, and maximum SR of 8.33  ×  10  −  6  RIU for TM mode. Corresponding to the TE mode maximum WS of 11,000  nm  /  RIU, AS of 12,180  RIU  −  1 and maximum SR of 9.09  ×  10  −  6  RIU are obtained. The proposed sensor with the Au–TiO2 configuration presents a maximum WS of 12,000  nm  /  RIU, AS of 20,370  RIU  −  1, and maximum SR of 8.33  ×  10  −  6  RIU for the TM mode. Corresponding to the TE mode maximum WS of 13,000  nm  /  RIU, AS of 18,100  RIU  −  1 and maximum SR of 7.69  ×  10  −  6  RIU is obtained. The maximum values of the sensor features are obtained for the analyte with RI 1.375 RIU for both configurations. Finally, a comparison between sensing parameters of plasmonic material ITO and TiO2 is performed, and optimum material is identified when used with Au for RI sensing.