The Plasmonic Pixel: Large Area, Wide Gamut Color Reproduction

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The Plasmonic Pixel: large area, wide gamut color reproduction using aluminum nanostructures Timothy D James, Paul Mulvaney, and Ann Roberts Nano Lett., Just Accepted Manuscript • DOI: 10.1021/acs.nanolett.6b01250 • Publication Date (Web): 10 May 2016 Downloaded from http://pubs.acs.org on May 12, 2016

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The Plasmonic Pixel: large area, wide gamut color reproduction using aluminum nanostructures Timothy D. James1‡*, Paul Mulvaney2‡ and Ann Roberts1‡. 1

School of Physics, The University of Melbourne, Victoria 3010, Australia

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Bio 21 Institute and School of Chemistry, The University of Melbourne, Victoria 3010,

Australia KEYWORDS: Nanoplasmonics, nanophotonics, aluminum plasmonics, nanoimprint lithography, electron-beam lithography, plasmonic printing, color printing

ABSTRACT: We demonstrate a new plasmonic pixel (PP) design that produces a full-color optical response over macroscopic dimensions. The pixel design employs arrays of aluminum nanorods ‘floating’ above their Babinet complementary screen, Concepts from conventional CMYK printing techniques and RGB digital displays are integrated with nanophotonic design principles and adapted to the production of PP elements. The fundamental PP color blocks of CMYK are implemented via a composite plasmonic nano-antenna/slot design, and then mixed in a digital display analog 3x3 array to produce a broad-gamut PP. The PP goes beyond current investigations into plasmonic color production by enabling a broad color gamut and physically large plasmonic color features/devices/images. The use of nano-rods also leads to a color

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response that is polarization tunable. Furthermore, devices are fabricated using aluminum and the fabrication strategy is compatible with inexpensive, rapid-throughput, nanoimprint approaches. Here we quantify, both computationally and experimentally, the performance of the PP. Spectral data from a test palette is obtained and a large area (> 1.5 cm lateral dimensions) reproduction of a photograph is generated exemplifying the technqiue.

TEXT The field of plasmonics research is rapidly maturing, and plasmonic structures are already being incorporated as optical elements into biomedical and other sensors 1, light sources 2 and in photovoltaic systems 3. One emerging field of plasmonics research involves taking advantage of the spectral properties of the resonances of optical nano-antennas for the production of devices and thin films producing characteristic reflected or transmitted colors 4-14. This growing interest in plasmonics for color-based applications is driven by the advantages plasmonic structures have over conventional pigment and printing based technologies. These benefits include a vastly increased spatial resolution 5, a reduction in the complexity of multistep color printing processes, and the potential to reduce the environmental impact of printing via use of recyclable and abundant materials such as aluminum 6. There are, however, critical problems with plasmonic color based devices that need to be addressed in order for this approach to become a viable alternative to conventional printing processes. These include: the limited color gamut and the achievable color saturation, relatively small device sizes and the complex color mapping algorithms necessary for creating accurate color plasmonic images and surfaces. Here, we demonstrate a large area, wide gamut plasmonic color printing process with a straightforward


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color-mapping algorithm that utilizes concepts from Red Green Blue (RGB) digital displays, Cyan Magenta Yellow Key (CMYK) color printing and Hue Saturation Value (HSV) colorpicking to create a Plasmonic Pixel (PP). This work brings a new level of control over the saturation and lightness of the reproduced color. Furthermore, the straightforward algorithm presented here is able to directly convert a desired RGB value to one of 2,980 plasmonic pixel colors through the use of only four different antenna array designs and a derivative of half-tone printing. A key property underpinning many current and potential applications of plasmonic nanoantennas is that of resonance. Although there is considerable interest in being able to produce broadband devices, the spectral response of nanoscale metallic particles and apertures in metallic films is associated with the excitation of localized resonances that have a limited bandwidth. The free-space wavelength and quality factor of these resonances depends on the geometry of an antenna, the metal of which it is composed and the local dielectric environment as well as the nature of the resonance. Arrays of rod-shaped nano-antennas are able to produce a color response through the selective absorption or reflection of portions of the visible spectrum 5, 15

and the complementary arrays of plasmonic nano-slots are able to transmit a given optical

bandwidth 7. By varying the dimensions of a plasmonic nanostructure, the peak absorption or transmission can be tuned across the visible spectrum if a suitable plasmonic material is selected. Gold and silver are by far the most commonly used plasmonic materials; gold is attractive for its excellent chemical stability and silver for its low dielectric loss and relatively high plasma frequency. These two materials, however, have serious limitations with respect to cost if large area plasmonic color structures are to be realized, and the inability to produce strong resonances in the blue part of the visible spectrum is a problem. Silver also exhibits poor physical stability


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due to oxidation and sulfidation. Aluminum becomes the material of choice for color plasmonic nanostructures as it permits access to the entire visible spectrum, is low cost and has excellent environmental stability due to its native oxide layer protecting nanostructures from physical degradation 16. The major downside of using aluminum nanostructures, on the other hand, is the relatively high optical loss compared to gold or silver, which increases with wavelength in the visible spectrum peaking at 800 nm due to interband transitions within the material 17. This optical loss has the effect of broadening plasmon resonances in aluminum optical nanostructures compared to those from identical gold and silver nanostructures. However, this broadening effect can be exploited through the careful design of the plasmonic nanostructure. Importantly, increased absorption in the red part of the visible spectrum can be utilized by enhancing the desired absorption of the nanostructure.

Figure 1. (a) Floating dipole design of the PP. A single element is used for the subtractive color palette, film and antenna thickness of 30 nm, gap between top of film and bottom of antenna of 50nm, antenna width of 30 nm, antenna length ranging from 50-120nm and a unit cell size of 250x250nm, (b) CIE Color Chart illustrating the response of an array of PP cells by varying the length of the floating dipole, (c) simulated reflectance spectra and perceived color with a D65 source for the PP design with varying floating dipole lengths, and (d) experimental reflectance spectra and photograph above the plot of the PP arrays with antenna lengths ranging from 50 to 120 nm (each square 200×200µm in size), (e) layout of the black pixel, (f)


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simulated and experimental spectra of the black pixel, where the color squares illustrate the observed color of each spectrum under illuminant D65.

The floating dipole plasmonic nanostructure design shown in Figure 1(a) is the fundamental building block for the PP considered here. The rod shaped nanostructures have a distinct advantage over circular/disk antennas as the rod resonance is of greater intensity 18, 19 and as a result the color response is more saturated. However, the asymmetry of the structure does introduce a polarization dependence. The floating-dipole design takes advantage of the lossy nature of aluminum, as it acts as a tunable perfect absorber 20, where altering the length of the rod and slot alters the central wavelength of the peak optical absorption of the structure. For the experimental and simulation results presented in Figure 1(c) and (d) the spacing between the top of the perforated film and bottom of the floating dipole antenna is set to 50 nm, where the importance of this gap is discussed in detail later. The PP is illuminated from the rod side of the structure, and the presence of absorption minima in the reflectance spectra is used to generate a subtractive color palette. Specifically yellow, magenta and cyan colors are obtained with floating dipole lengths of 70, 90 and 120 nm, respectively. The major difference between the FEM simulation of the floating dipole design and the experimental results is the saturation of the observed yellow color response of the device. This trend is clearly observable in the CIE Color Chart shown in Figure 1(b), where the simulation and experiment are nearly identical, except for the shortest antenna lengths, corresponding to the yellow part of the chart. This variation is primarily due to the roughness of the evaporated aluminum films, caused by relatively large grain sizes, which results in a broadening of the resonance and a reduction in the relative intensity. This in turn leads to less saturated “yellows” as predicted by the simulation. The challenge to produce strongly saturated yellow colors could be overcome with further


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optimization of the aluminum evaporation process by adjusting evaporation parameters such as evaporation rate and substrate temperature. To achieve a full subtractive color palette capable of replicating the CMYK printing process, the K or black is required. In theory, the combination of CMY should produce black, but, in practice, it tends to be perceived by eye as an unsatisfactory muddy-brown. As shown in Figure 1(a), black is achieved by creating a broad-band near-perfect absorber using a two-element floating dipole design of floating dipole with antenna lengths of 70 and 110 nm, and a center-tocenter spacing of 125 nm. This two-element design is compatible with the single element design strategy, in that it requires the same unit-cell size, and the same spacing between the thin film and nano-antenna. Figure 1(f) shows that by combining two nano-antennas in a single cell, a broad absorption response can be achieved. The observed colors corresponding to the simulated and experimental spectra are shown as colored squares, in Figure 1(f), where a D65 source has been used as the illumination source. The PP floating dipole was designed with mass-production in mind and the structures can be easily fabricated via nano-imprint lithography

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. The floating dipole and slot are encased in

polymer and glass, and are designed to be completely compatible with roll-to-roll nanoimprinting using plastics and resins as the encasing layers, which can be fabricated over large areas at a very rapid rate

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. In this work, test structures are fabricated via electron beam

lithography (EBL), using PMMA as a resist, where the aluminum is evaporated directly onto the glass/PMMA wafer, and over-coated with silicon dioxide. The details are presented in the supplementary material.


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The floating dipole design of the PP operates as a narrowband plasmonic near-perfect absorber, enabling highly saturated subtractive colors to be reproduced. Plasmonic perfect absorbers typically function via the coupling of a resonant antenna structure to a mirrored resonance in a metallic film located within the near field of the resonating antenna

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. This

interaction between the antenna and film can simply be described as two dipoles coupling due to the presence of another antenna-induced dipole resonance in the thin film, leading to two new resonant modes arising from plasmon hybridization

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. Further detailed discussion of plasmon

mode hybridization of the PP floating dipole design is presented in the supplementary material. The critical importance of the coupling distance between nano-antenna and thin film substrate is often overlooked in color producing plasmonic device systems. Discrepancies in the distance between the perforated metallic film and the nano-antennas of just a few tens of nanometers will result in a highly desaturated color response, essentially rendering the antennas invisible. Figure 2 presents the simulated reflectance spectra of an 85 nm long floating dipole antenna of 30 nm width and thickness, where the gap between the antenna and perforated 30 nm thick film is varied from 10-470 nm. The simulation was performed with the Finite Element Method (FEM) implemented in COMSOL Multiphysics 4.4 software. The reflectance spectra collected from the antenna/film system display a number of clearly defined features, namely (i) coupling between the nano-antenna and film at distances < 90nm, and (ii) striking thin-film interference effects for gaps > 90nm. The intensity of the coupling is evidenced by the red-shifting of the resonance of the antenna/film system with reduced antenna/film gap - the stronger the coupling, the greater the red-shift. In terms of color response, at very small antenna/film gaps (< 20 nm) the structure generates a cyan color rather than magenta, demonstrating the significant effect the gap has on the spectral response.


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Beyond the near-field plasmon/plasmon coupling regime between the metallic thin film and nano-antenna, where significant resonant spectral shifting occurs, thin film effects have a dramatic effect on the intensity of the plasmon resonance and resulting color response. From Figure 2 it is clear that placing the antenna at distances of mλ/2 from the aluminum film, where m is an integer and λ the wavelength in the coating, completely extinguishes the antenna resonance. This phenomenon is due to the antenna being located in a region of very low electric field, generated by thin film interference effects. This results in a flat reflectance spectrum of approximately 90%, as expected for a bare Al mirror

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. Conversely, locating the antenna at

distances at (2m +1)λ/4 places the antenna in the vicinity of electric field maxima and results in a strong resonance with associated saturated color response.

Figure 2 Plot of the reflectance for an 85nm PP in a 250nm cell, with an increasing gap between the floating dipole and thin film. Note that as the distance is increased the coupling changes from being dominated by plasmon/plasmon coupling between the antenna and film, to plasmon/photonic coupling between the plasmon resonance and optical cavity mode


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Figure 3 Algorithm for designing a PP from a desired RGB pixel, (a) fundamental size and layout of the PP, with detail on color sub-pixel, (b) converting RGB to HSV to extract Value that determines number of black sub-pixels, Saturation is then used to determine ratio of color to white for remaining sub-pixels, (c) using Hue to determine ratio of CMY for color sub-pixels

The central feature of the PP is the ability to take the CMYK color response of the floating dipole design, and arrange these structures using an algorithm that permits the tuning of the saturation and brightness of the perceived color, and the mixing of the CMYK color palette to produce a high fidelity, wide color gamut device. Previous studies on expanding the color gamut of plasmonic devices have focused on optimizing the nanostructure design to increase the saturation of the perceived color of the plasmonic device 5, 27, 28 Our aim is to go well beyond this by enabling the control of saturation and brightness of plasmonic based color devices, and to increase the available color gamut through color mixing, rather than increased saturation.


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Figure 3 illustrates the design flow for producing the layout for the PP. Figure 3(a) illustrates how each PP is 30x30µm in size, and is composed of a 3x3 array of sub-pixels, each of these comprising in turn a 10x10µm array of floating-dipole antennas. The image resolution of these 30x30µm pixels corresponds to 841 Pixels Per Inch (ppi), which is very close to the physical resolution limit of the human eye of approximately 900 ppi. This defined size of the PP can be expanded or decreased as desired. The color of the PP is defined by selecting one of three options for each of the sub-pixels in a given PP, which can either be blank to produce white to tune saturation, black to tune lightness, or color to set the desired hue. As shown in Figure 3(b), the desired pixel color is broken down into its HSV components to separate the saturation of the color (Saturation), the lightness (Value) and color tone (Hue). Firstly, the Value of the color is used to determine the proportion of sub-pixels that are either black or white/color, then Saturation is used to determine the ratio of color to white sub-pixels remaining after the Value calculation. The Hue of the desired color is then extracted, which is converted to a ratio of cyan, magenta and yellow (CMY) hues that is used to determine the makeup of the color sub-pixels. Each of the 10 x 10 µm color sub-pixels is split into 10 x 1µm strips of 10 µm length, and the ratio of CMY for the given Hue is used to select the colors for each of the strips in the sub-pixel. For the example in Figure 3(c) the Hue is very close to a pure red color, which would require an even ratio of yellow and magenta strips to produce the red hue and no cyan. As Figure 3 shows, the design algorithm can produce 2,980 different colors and shades through the 45 unique combinations of white/black/color sub-pixels, of which there are 66 combinations of CMY color sub-pixels, resulting in 2,970 unique combinations. In addition to the 2,970 sub-pixel combinations involving color, there are 10 combinations of black/white only sub-pixels, making a total of 2,980 different color and shade combinations available.


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Figure 4 (a) Color mixing test pattern to observe saturation and brightness control of the PP design algorithm, (b) in focus 5x magnified photograph of fabricated test pattern illustrating the PP sub-pixel arrangement, (c) out-of-focus photograph illustrating the smooth brightness/saturation transitions and color mixing observed with the naked eye. Reflectance measurements of subtractive colors to achieve additive colors (d) yellow + magenta to give red, (e) yellow + cyan to give green, (f) magenta + cyan to give blue, (g) SEM image of a color mixing region illustrating two different color regions, (h) magnified SEM image of the backside of the cyan floating dipole design, and of the back of the black floating dipole design, (i) cross-sectional SEM image of the floating dipole design

Test structures were fabricated to demonstrate the capabilities of the PP algorithm, permitting control of brightness, saturation and color tone in plasmonic color devices. Figure 4 (a) presents the test pattern used to demonstrate the capabilities of the PP, where saturated versions of the primary subtractive and additive color spaces are varied from completely de-saturated, to saturated. Figure 4 (b) and (c) show magnified photographs of the fabricated test structure, where the focused image, (b), illustrates how the sub-pixels are varied to achieve the smooth gradient of saturation and brightness through the mixing of white and black sub-pixels, respectively. Figure 4 (c) is a defocused magnified photograph of the test structure, and is representative of what is observed with the unaided eye, where the sub-pixels merge to produce smooth variations in


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saturation and brightness. Figure 4 (d), (e) and (f) show the measured reflectance spectra for the subtractive color mixing of CMY to produce RGB, where the averaging of the two mixed subtractive colors produce the resulting additive color. It is clear from Figure 4(e) that green is the most difficult color to achieve with the design presented here. This difficulty is due to the broadening of the resonances used to produce the mixing colors, yellow and cyan, as the overlap between the two resonances is too large, and this significantly reduces the intensity of the resulting green color. The challenge of producing green could be overcome by increasing the fidelity of the nano-structures and reducing the grain size of the aluminum film, which would result in narrower yellow and cyan resonances, and therefore a more saturated green response. Included in Figure 4 are SEM images of the of the PP design, where the slots are observable in Figure 4 (h) for the cyan colored sub-pixel and for the double-antenna black sub-pixel in a top down view of the floating-dipole design. A cross-sectional SEM image of the floating-dipole design is presented in Figure 4(i), where the Al dipole antennas are clearly separated by the PMMA layer from the perforated Al film above, creating the floating-dipole structure. It is clear from these images the fidelity of the patterning is excellent, despite the non-ideal grain size of the aluminum film. To demonstrate the capacity of the PP design to produce complex images with a wide range of shade, saturation and lightness over a macroscopic area, a historic photograph taken by Mervyn Bishop was replicated, as shown in Figure 5(a). The long edge of the PP image shown in Figure 5 (b) and (c) is 1.5 cm long, where the fine details of skin and clothing tone and shade are easily visible to the naked eye. The 6 blocks at the top left hand of the PP images are test arrays with dimensions of 390 x 390 µm, reproducing (from left to right) pure cyan, magenta, yellow, red, green and blue. The two PP images illustrate the ability to switch color “off and on” through the


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use of a polarizer, where the black sub-pixels turn a dull brown and all color sub-pixels turn a desaturated green color under off-polarization. The prototype shown in Figure 5(b) and (c) displays some notable artifacts from the EBL process, where there are proximity errors prevalent at the edges of each individual write field (approximately a 1x1 mm2 area), which manifests as the patchwork-like effect most obvious in the sky region of Figure 5 (c). This patchwork artifact from the EBL processing can be overcome by applying proximity error correction, which for a pattern of such size and density is a challenging process, yet readily achievable with time and effort.

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Figure 5 (a) Image taken in 1975 by Mervyn Bishop of Australian Prime Minister Gough Whitlam pouring sand into the hand of the leader of the Gurindji communities, Vincent Lingiari, symbolically handing the Wave Hill station back to the Gurindji people, used with permission from the Art Gallery of New South Wales, (b) PP reproduction, long edge of 1.5cm length, with xaxis aligned polarizer (c) image taken with polarizer aligned to y-axis.

The viewing angle sensitivity of the PP design was also investigated. It is expected from simulations and literature 6, 20 that these PP generated images should be largely angle-insensitive. This is apparent in Figure 6 where it can clearly be seen that the polarization color response of


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the device is obvious even up to a 70° viewing angle. Only at a viewing angle of 80° does diffraction generated by the periodicity of the unit cells become obvious.

Figure 6 Investigating viewing angle sensitivity from 10-80° for both polarizations. Top: x-polarization; Bottom: y-polarisation.

In conclusion, we have experimentally demonstrated the applicability of the PP to the production of a large area, polarization sensitive, optical device. There are a number of parameters critical to the fabrication of the plasmonic based device, specifically the length of the nano-antennas required to tune the desired color, and just as importantly, the spacer gap between the antenna and film plane, which has direct control over the achievable color saturation of the structure. The algorithm used to convert a digital image file into the layout for the PP, which provides the PP the capability of producing 2,980 different colors, is detailed. The plasmonic nano-antenna foundation of the PP enables the optical device to be very sensitive to polarization, while maintaining viewing angle insensitivity. The strategy presented is compatible with nano-


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imprint lithography implementations of the approach, facilitating fast, scalable approaches to fabrication.

ASSOCIATED CONTENT Supporting Information Available: Optical measurement and fabrication process details are provided, along with a discussion on the applicability of the process with nano-imprint lithography. The resonant mode properties of the floating dipole structure are investigated. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. ‡These authors contributed equally. Funding Sources Australian Research Council's Linkage Projects funding scheme (project number LP110200319). ACKNOWLEDGEMENTS


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This research was supported by the Australian Research Council through LP110200319 and LF100100117. The authors acknowledge useful conversations with Jasper Cadusch and thank Sergey Rubanov of the Bio21 Microscopy Centre for the SEM cross-section. This work was performed in part at the Melbourne Centre for Nanofabrication (MCN) in the Victorian Node of the Australian National Fabrication Facility (ANFF). REFERENCES 1. Anker, J. N.; Hall, W. P.; Lyandres, O.; Shah, N. C.; Zhao, J.; Van Duyne, R. P. Nature Materials 2008, 7, 442-453. 2. Okamoto, K.; Niki, I.; Shvartser, A.; Narukawa, Y.; Mukai, T.; Scherer, A. Nature Materials 2004, 3, 601-605. 3. Chen, X.; Jia, B.; Saha, J. K.; Cai, B.; Stokes, N.; Qiao, Q.; Wang, Y.; Shi, Z.; Gu, M. Nano Letters 2012, 12, 2187-2192. 4. Shrestha, V. R.; Lee, S.-S.; Kim, E.-S.; Choi, D.-Y. Nano Letters 2014, 141103145623000. 5. Tan, S. J.; Zhang, L.; Zhu, D.; Goh, X. M.; Wang, Y. M.; Kumar, K.; Qiu, C.-W.; Yang, J. K. W. Nano Letters 2014, 140625134150006. 6. Clausen, J. S.; Højlund-Nielsen, E.; Christiansen, A. B.; Yazdi, S.; Grajower, M.; Taha, H.; Levy, U.; Kristensen, A.; Mortensen, N. A. Nano Letters 2014, 140708095444001. 7. Inoue, D.; Miura, A.; Nomura, T.; Fujikawa, H.; Sato, K.; Ikeda, N.; Tsuya, D.; Sugimoto, Y.; Koide, Y. Applied Physics Letters 2011, 98, 093113. 8. Kumar, K.; Duan, H.; Hegde, R. S.; Koh, S. C. W.; Wei, J. N.; Yang, J. K. W. Nature Nanotechnology 2012, 7, 557-561. 9. Xue, J.; Zhou, Z.-K.; Wei, Z.; Su, R.; Lai, J.; Li, J.; Li, C.; Zhang, T.; Wang, X.-H. Nature Communications 2015, 6, 8906-. 10. Goh, X. M.; Zheng, Y.; Tan, S. J.; Zhang, L.; Kumar, K.; Qiu, C.-W.; Yang, J. K. W. Nature Communications 2014, 5, 5361. 11. Zeng, B.; Gao, Y.; Bartoli, F. J. Scientific Reports 2013, 3. 12. Li, Z.; Clark, A. W.; Cooper, J. M. ACS nano 2016, 10, 492-498. 13. Olsona, J.; Manjavacas, A.; Liu, L.; Chang, W.-S.; Foerster, B.; King, N. S.; Knight, M. W.; Nordlander, P.; Halas, N. J.; Link, S. Proceedings of the National Academy of Sciences 2014, 111, 14348-14353. 14. Zhu, X.; Vannahme, C.; Hojlund-Nielsen, E.; Asger Mortensen, N.; Kristensen, A. Nature Nanotechnology 2015, 11, 325. 15. Si, G.; Zhao, Y.; Lv, J.; Lu, M.; Wang, F.; Liu, H.; Xiang, N.; Huang, T. J.; Danner, A. J.; Teng, J.; Liu, Y. J. Nanoscale 2013, 5, 6243-6248. 16. Knight, M. W.; Liu, L.; Wang, Y.; Brown, L.; Mukherjee, S.; King, N. S.; Everitt, H. O.; Nordlander, P.; Halas, N. J. Nano Letters 2012, 121022121920007. 17. Diest, K.; Liberman, V.; Lennon, D. M.; Welander, P. B.; Rothschild, M. Optics Express 2013, 21, 28638-28650.


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18. Lalisse, A.; Tessier, G.; Plain, J.; Baffou, G. Journal Of Physical Chemistry C 2015, 119, 25518-25528. 19. Mertens, H.; Polman, A. Journal Of Applied Physics 2009, 105, 044302. 20. Liu, N.; Mesch, M.; Weiss, T.; Hentschel, M.; Giessen, H. Nano Letters 2010, 10, 23422348. 21. Bergmair, I.; Dastmalchi, B.; Bergmair, M.; Saeed, A.; Hilber, W.; Hesser, G.; Helgert, C.; Pshenay-Severin, E.; Pertsch, T.; Kley, E. B.; Hübner, U.; Shen, N. H.; Penciu, R.; Kafesaki, M.; Soukoulis, C. M.; Hingerl, K.; Muehlberger, M.; Schoeftner, R. Nanotechnology 2011, 22, 325301. 22. Ahn, S. H.; Guo, L. J. ACS nano 2009, 3, 2304-2310. 23. Wang, D.; Zhu, W.; Best, M. D.; Camden, J. P.; Crozier, K. B. Scientific Reports 2013, 3. 24. Prodan, E.; Radloff, C.; Halas, N. J.; Nordlander, P. Science 2003, 302, 419-422. 25. Ameling, R.; Giessen, H. Laser & Photonics Reviews 2012, 7, 141-169. 26. Butet, J.; Martin, O. J. F. Plasmonics 2014, 10, 203-209. 27. Hu, X. L.; Sun, L. B.; Zeng, B. B.; Wang, L. S.; Yu, Z. G.; Bai, S. A.; Yang, S. M.; Zhao, L. X.; Li, Q.; Qiu, M.; Tai, R. Z.; Fecht, H. J.; Jiang, J. Z.; Zhang, D. X. Applied Optics 2016, 55, 148-152. 28. Sun, L. B.; Hu, X. L.; Beibei, Z.; Wang, L. S.; Yang, S. M.; Tai, R. Z.; Fecht, H. J.; Zhang, D. X.; Jiang, J. Z. Nanotechnology 2015, 26, 305204.


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(a)

(c)

30nm

100 80

50nm

30nm

120nm

(e)

FEM Simulations

60 40 20 0 400

0.9

FEM Simulation Experimental

0.8 0.7 0.6

80

0.4 0.3

50nm 120nm

Wavelength (nm)

650

700

120nm

100

Experimental

80

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

x

Experimental

FEM Simulation Experimental

60 40 20

20 0 400

FEM Simulation

(f)

40

0.1 0

600

60

0.2

0

550

Reflectance (%)

0.5

500

50nm

(d) 100

450

Reflectance (%)

(b)

y

50nm

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Reflectance (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Nano Letters

450

500

550

600


Wavelength (nm)

650

700

0 400

450

500

550

600

Wavelength (nm)

650

700

3λ

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0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0

470

Film/Antenna Gap (nm)

Reflectance

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

5λ

2

Reflected Color

Nano Letters

λ

4

410

3λ

350

4

+ 0

290

λ

230

2

170 110

λ

50 10 400

Surface Charge

450

500

550

600

650

700

Wavelength (nm)

750

800


4

-

Plasmonphotonic coupling

Plasmonplasmon coupling

(a)

(b)

30µm

30µm

(c)

RGB Pixel R: 101 G: 102 B: 174 Value

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RGB Pixel R: 101 G: 102 B: 174 Hue

Saturation

10µm

1

10µm

0°

354°

Value

Color Sub-Pixel Layout Each strip either CM or Y

10µm

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0 Saturation 1 Value: 0.81 Saturation: 0.49

1µm

0

Hue: 354°

K (black): 2 White: 4 Color: 3

C: 0.00 M: 0.99 Y: 0.96

C B/W/C Layout

C

Color Pixel Addition

C 3x3 PP Layout

Sub-Pixel Layout ACS Paragon Plus Environment

Complete Plasmonic Pixel

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(a)

(b)

(c)

100

Reflectance (%)

80

(d)

60 40 20 0

100

Reflectance (%)

80

(g)

(h)

1.1mm

450

500

550

600

650

700

500

550

600

650

700

Wavelength (nm)

(e)

60 40

0

(i)

250nm 10µm

400

20

250nm

400nm


PMMA SiO2

Al

100 80

Reflectance (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Nano Letters

400

450

Wavelength (nm)

(f)

60 40 20 0

400

450

500

550

Wavelength (nm)

600

650

700

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

1.5cm

Nano Letters


1.25cm

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Nano Letters


Nano Letters

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25


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The Plasmonic Pixel: Large Area, Wide Gamut Color Reproduction

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