In this paper, the characteristics of the Silica TFBG type of optical fiber, which has a wavelength of 1550 nm, were investigated and enhanced. Specifically, the refractive index was used to sense various sodium nitrate concentrations. The optical fiber's thickness was then lowered chemically using 10% hydrofluoride acid, and gold film was applied using the SPR technique. The findings demonstrated a shift in the wavelengths of the transmitting light spectrums, as well as an increase in power and, consequently, sensitivity .