In recent years, chemical and biological sensing using plasmonic nanostructures has gained significant attention due to their ability to detect a wide range of small chemical molecules, from biomarkers to narcotics. The primary appeal of the surface plasmon resonance (SPR) technique lies in the induction of a polariton at the metal–insulator interface under coupled conditions, which manifests as a distinct intensity minimum in reflectance spectra. In this study, a Cu/Ta₂O₅/Cu MIM-based nanostructure is proposed as a means to produce well-defined (narrow and deep) plasmonic responses that experience pronounced angular shifts when the surrounding dielectric environment changes. In other words, this enables the development of a precise thin-film-based chemical compound detection system. The approach relies on amplifying the near-field interaction between adjacent metal films by incorporating a high-optical-density dielectric layer only a few nanometers thick. Finite-element numerical simulations were used to guide the geometric optimization of the nanostructures, yielding optimal MIM dimensions of 20/5/20 nm, and the resulting systems were deposited at room temperature via non-reactive RF magnetron sputtering using an Intercovamex S16 system. Experimental validation was performed using angular interrogation in the Kretschmann configuration with a 633 nm light source.