A photonic crystal fiber sensor is designed and analyzed based on the interaction of guided light with plasmonic layer of Au deposited both externally and internally to undergo surface plasmon resonance (SPR). The sensor has eight microchannels with Au of thickness of 0.03 μm surrounding them. For internal metal deposition, Au layer of 0.03 μm is also deposited internally outside analyte filled in inner layer of PCF holes. The sensor is found to have maximum confinement loss of 642.38 dB/cm in the RI range of 1.35–1.45 RIU. The confinement loss peak at the resonating wavelength is utilized to detect analytes in wide detection range with maximum wavelength sensitivity of 250 nm/RIU and amplitude sensitivity of 7.77 RIU−1. The proposed sensor is also compared in performance with modified sensor design using dual plasmonic layers of Au and TiO2 in combination. The proposed sensor is found to outperform the dual layer plasmonic sensor in terms of both sensitivity and full width half maxima (FWHM) value and can be used to detect a number of biochemicals of both low and high refractive indices owing to its wide detection range.