Abstract
Colour filters based on nano-apertures in thin metallic films have been widely studied due to their extraordinary optical transmission and small size. These properties make them prime candidates for use in high-resolution colour displays and high accuracy bio-sensors. The inclusion of polarization sensitive plasmonic features in such devices allow additional control over the electromagnetic field distribution, critical for investigations of polarization induced phenomena. Here we demonstrate that cross-shaped nano-apertures can be used for polarization controlled color tuning in the visible range and apply fundamental theoretical models to interpret key features of the transmitted spectrum. Full color transmission was achieved by fine-tuning the periodicity of the apertures, whilst keeping the geometry of individual apertures constant. We demonstrate this effect for both transverse electric and magnetic fields. Furthermore we have been able to demonstrate the same polarization sensitivity even for nano-size, sub-wavelength sets of arrays, which is paramount for ultra-high resolution compact colour displays.
Highlights
Of particular interest is the high sensitivity of these devices which allows the detection of small changes in the dielectric constant within the near-surface region
We show that using cross-shaped apertures in combination with polarization control it is possible to generate two-colour spectra but a continuously tunable colour palette which is a key step for applications including high-resolution chemical sensing and miniaturised displays
Using analytical expressions for localized surface plasmon (LSP), surface plasmon polaritons (SPPs) and Rayleigh anomalies (RA), we present a detailed theoretical study exploring the origin of the resonant peaks and how they relate to the shape and periodicity of the apertures
Summary
Of particular interest is the high sensitivity of these devices which allows the detection of small changes in the dielectric constant within the near-surface region. Resonant frequency is sensitive to both the periodicity of the holes as well as their size[15,16,28] This limits the smallest achievable device size and implies the need for specific methods to be developed to correct for ‘stitching’ artefacts when arrays of circular apertures are used to create pixels in colour displays[29]. These methods are not straightforward to implement and require considerable effort to realize effective colour separation. We demonstrate that full functionality is retained from individual plasmonic ‘pixels’ of just a few hundreds of nanometres in size
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