Devices, systems, and methods for detection of an analyte in a sample are disclosed. In some embodiments, an optical sensor can include a metallic layer and a plurality of dielectric pillars extending through the metallic layer. A plurality of regions of concentrated light can be supported in proximity to the ends of the plurality of dielectric pillars when a surface of the metallic layer is illuminated. Concentrated light within one or more of these regions can interact with an analyte molecule, allowing for detection of the analyte.
