Leveraging the phenomenon of Surface Plasmon Resonance (SPR), researchers nowadays integrate its principle with powerful tools in the optical sensing industry, such as fiber optics (FO). Plastic optical fiber (POF) has become a favourable
choice due to its flexibility, durability, and cost-effectiveness. Conventional SPR sensors suffer from complex configuration and low sensitivity, thus, this study modified a standard POF into U-bent D-shaped and integrated it with SPR sensor with
the aim of optimizing the SPR sensor. The POF was coated with silver (Ag) as plasmonic material, then tested in refractive index (RI) and salinity level sensing for a certain liquid. To further the study, the fiber was then coated with tin diselenide (SnSe2) onto Ag layer to enhance the performance of the sensor in terms of sensitivity and stability due to its characteristic, which is large surface-to-volume ratio.