In this work, a photonic sensor based on photonic crystal fiber and surface plasmon resonance to analyze the refractive index (RI) of analytes varying from 1.440 to 1.480 is presented. A dual hexagonal lattice of air holes is reported in this proposed sensor design. The combination of titanium dioxide (TiO₂) and gold (Au) is used as a plasmonic material in this sensor. The sensing capability of the proposed sensor is inspected in terms of wavelength sensitivity, amplitude sensitivity, sensor resolution, linearity of resonance wavelength, and figure of merit (FOM). Theoretical analysis of the sensor is performed for both quasi TM mode and quasi TE mode. Numerical investigation shows that wavelength sensitivity of 12  ,  000  nm RIU^−  1, is obtained for both TM mode and TE mode using the wavelength interrogation method. AS of 3307 and 3619  RIU^−  1 is obtained for TM mode and TE mode, respectively, using the amplitude interrogation method. A maximum sensor resolution of 8.33  ×  10^−  6  RIU is obtained for both TM mode and TE mode, respectively. The linear relationship of resonant wavelength with RI produces R²  =  0.9991 and R²  =  0.9970 for degree 2, for TM mode and TE mode, respectively. The FOM obtained from the proposed sensor is 139.53 and 187.50 for TM mode and TE mode, respectively.