Microstructures and nanostructures (100) consisting of a substrate (110), an array of pillars (120) capped by metallic disc (130), metallic dots (clusters or granules) (140) disposed on the sidewalls of the pillars, and a metallic backplane (150) that can interact to enhance a local electric field, the absorption of the light, and the radiation of the light are disclosed. Methods to fabricate the structures (100) are also disclosed. Applications of the structures to enhance the optical signals in the detection of molecules and other materials on a structure surface, such as fluorescence, photoluminescence and surface enhanced Raman Scattering (SERS) are also disclosed.