In this letter, we propose and experimentally demonstrate a color filter based on an annular aperture geometry working in the visible range. The device is built by configuring an array of annular apertures in a gold film suitable for transmission measurement. We show effective fine tuning of resonance peaks through precise geometric control of the aperture dimensions. Selective transmission through annular apertures of various sizes leads to continuous color tuning of transmitted electromagnetic waves. This may find potential for application in high-definition displays, optical filters, ultrafast switching, and bio-sensing.
Recent developments have shown that light's orbital angular momentum (OAM) can be harnessed for a diversity of emerging applications and generated by miniaturized OAM generators. Nanostructured flat logarithmic‐spiral zone plates (LSZPs) are proposed to produce as well as focus optical vortices with a long focal depth in the broadband visible range. Topologically breaking the in‐plane symmetry, this nanoengineered LSZP continuously modulates both amplitude and phase in the diffraction field to shape twisted focusing of the optical vortex beam, which is microscopically confined and spatially spiraling with variant crescent‐shaped transverse intensity profiles. Owing to its rich structural degree of freedom upon aperiodic and continuously variant features, the LSZP provides a compact solution to generate and control optical vortices carrying scalable OAM and highly concentrated photons with a high transmission efficiency of ∼22%. This can offer new opportunities for 3D light shaping, optical manipulation, flat optics, and photonics miniaturization and integration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.