In this paper, proposed plasmonic nanostructure is designed to increase the spatial resolution of optical imaging system by amplifying a specific signal while producing a plasmonic effect via a nanoantenna and grating nanostructure. We utilized antenna theory and grating structure to enable the surface plasmon effect and coupling electric field to be focused center of unit cell and enhance the optical signal of 785 nm wavelength. We confirmed that a proposed plasmonic nanostructure can be used

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... o enhance electric fields in specific angle of incident light, 30° and attain a far-field gain of 1137, enabling a more finely resolved optical signal to be obtained. In experiment, the proposed plasmonic nanostructure was confirmed to enhance optical signal of laser by 2.24 times and also confirmed enhancing electric field using AFM. Moreover, when applied in functional near-infrared spectroscopy and fluorescence imaging systems, it was confirmed that an indistinguishable signal can be distinguished by amplifying the optical signal 76 times, and a specific wavelength can also be enhanced. Accordingly, the incorporation of these nanostructures should increase the utility of the collected data and enhance optical signals for applications in optics, bioimaging, and biology.