Abstract
Highly efficient polarization-tuned structural color filters, which are based on a one- dimensional resonant aluminum grating that is integrated with a silicon nitride waveguide, are proposed and demonstrated to feature a broad color palette. For such a metallic grating structure, transmissive color filtering is only feasible for the incident transverse-magnetic (TM) polarization due to its high reflection regarding the transverse-electric (TE) case; however, polarization-tuned customized colors can be efficiently achieved by optimizing the structural parameters like the duty ratio of the metallic grating. For the fabricated color filters, the transmission peaks, which are imputed to the resonance between the incident light and the guided modes that are supported by the dielectric waveguide, provided efficiencies as high as 90% and 70% for the TM and TE polarizations, respectively, as intended. Through the tailoring of the polarization, a group of filters with different grating periods were successfully exploited to produce a broad color palette spanning the entire visible band. Lastly, a nanoscale alphabetic pattern featuring a flexible combination of colorations was practically constructed via an arrangement of horizontal and vertical gratings.
Highlights
Peaks for both the TM and TE polarizations simultaneously, thereby producing vivid customized colors
Efficient polarization-mediated structural color filters that capitalize on an ultrathin Al grating in conjunction with a dielectric waveguide, and which provide transmission efficiencies up to 90% and 70% for the TM and TE polarizations, respectively, have been devised and evaluated
A broad color palette was realized over the entire visible band by adjusting the period of the metallic grating, as well as dynamically changing the incident polarization
Summary
Peaks for both the TM and TE polarizations simultaneously, thereby producing vivid customized colors. The operation of the device is thoroughly analyzed in terms of the transmission response and the corresponding color properties, as well as the evolution of the resonant field profiles. A group of different color filters and an elaborate nanoscale pattern that is constructed by appropriately combining them are practically fabricated so as to confirm an arbitrary coloration set through the adjustment of the polarization and the grating period. It is predicted that the proposed devices can readily be applied to applications such as ultrafast display devices, security tags, anti-counterfeiting, and optical data storage[5,18,19,20,21]
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