Polarization-Controlled Broad Color Palette Based on an Ultrathin One-Dimensional Resonant Grating Structure

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.

Nano-structured transmissive spectral filter matrix based on guided-mode resonances

“…Moreover, as stated in some previous works [30,31], the metal grating based GMR filter is polarization dependent. The filter matrix can be thus fabricated containing both vertical and horizontal gratings with the same periods, to compensate the polarization dependency.…”

“…The magnetic field is no longer confined at the aluminum and dielectric layer interface when the buffer layer exists. This phenomenon is due to the presence of surface plasma mode, and the buffer layer could lead to a narrow plasmonic bandgap [30,31]. Moreover, the transmission spectrum of the filter with ITO as buffer layer has a FWHM around 3 times larger than that of SiO 2 as buffer layer with the same structural parameters.…”

Nanostructured Color Filters: A Review of Recent Developments

“…The reported pixel bandwidth was 12 nm [96]. Similarly, Koirala et al [97] presented a highly efficient polarization controlled structural color filter based on an ultra-thin 1D resonant Al-based grating structure with silicon nitride as a guided layer. It was proposed that 0.5 duty cycle (required to fulfill the guided mode resonant condition) allows transmission in TE and TM mode.…”

Reflective color filter with precise control of the color coordinate achieved by stacking silicon nanowire arrays onto ultrathin optical coatings

“…Moreover, compared to the traditional pigment-based color printing, structural color printing enables a remarkably higher printing spatial resolution (~two-orders of magnitude) 7 . The resonant wavelength of such nanoscale coloration can be tuned by controlling the geometrical parameters of the building blocks, such as their size 8–15 , shape 10,16 , period 12,13,17–19 , and thickness 20–24 . Among the various candidates for nanoscale coloration, silicon (Si) nanostructures are considered as the most suitable candidates because of the low-cost/mature fabrication process and high color purity 25–30 resulted from the low absorption loss of Si.…”