Tuning plasmon resonance in depth-variant plasmonic nanostructures.

We demonstrate coaxial-aperture-based plasmonic nanostructures for tunable plasmon resonances in optically thick metal films. Accurate control of etching depth is achieved via cross-section investigation under a scanning electron microscope. Colorful surfaces are observed with varying geometries. The approach developed in this work is potentially useful for optical devices design and development in nanophotonics and integrated optics, especially for imaging and display applications. [ABSTRACT FROM AUTHOR]