We propose a design of angle-insensitive and polarization-independent reflective color filters with high efficiency ( > 80%) based on broad resonance in a Fabry-Pérot cavity where asymmetric metal-dielectric-metal planar structures are employed. Broadband absorption properties allow the resonance in the visible range to remain nearly constant over a broad range of incident angles of up to 40° for both s- and p-polarizations. Effects of the angles of incidence and polarization state of incident light on the purity of the resulting colors are examined on the CIE 1931 chromaticity diagram. In addition, higher-order resonances of the proposed color filters and their electric field distributions are investigated for improved color purity. Lastly, the spectral properties of the proposed structures with different metallic layers are studied. The simple strategy described in this work could be adopted in a variety of research areas, such as color decoration devices, microscopy, and colorimetric sensors.
3. Conclusions 4. Conclusion In conclusion, we have shown a scheme of creating highly efficient (>80%) reflective RGB colors In conclusion, we have shown a scheme of creating highly efficient (>80%) reflective RGB colors with angle-insensitive and polarization-independent properties exploiting broad optical resonances in ultrathin planar nanostructures simply consisting of four layers. The resonant wavelengths of the proposed color filter structures remain nearly constant over a broad range of incident angles for both sand p-polarizations, which are ascribed to the broad optical resonance effects. Besides, it is shown how both incident angles and polarizations have influence upon the reflection spectrum and hence the colors produced by the nanostructures. It is also demonstrated that improving color purity for a certain color is enabled by employing higher-order resonances. Furthermore, the dependence of the spectral reflection properties on different metallic layers is examined. The approach proposed here potentially paves the way towards numerous applications such as colored solar cells, color decorations, and wavelength-selective photodetectors. Author Contributions: The manuscript was conceived by all authors. K.-T.L. and D.K. performed the simulations Author Contributions: The manuscript was conceived by all authors. K.-T.L. and D.K. performed the simulations and K.-T.L., D.K., H.J.P., D.H.P., and S.H. analyzed the results. K.-T.L. and D.K. wrote the draft manuscript which was edited by H.J.P., D.H.P. and S.H. Acknowledgments: This work was supported by the Ajou University research fund. This work was supported Acknowledgments: This work was supported by the Ajou University research fund. This work was supported by the Ministry of Trade, Industry and Energy (MOTIE, No. 10051565 & 20000512) and Korea Display Research industry. This work was partially supported by the GRRC program of Gyeonggi province (GRRC AJOU Corporation (KDRC) support program for the development of future devices technology for display industry. by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the PMhiontiosntriycso-Mf Secdiiecnacl eC, IoCnTvearngdenFcue tTuerechPnlaonlongiyngR(eGseraarncthn Co.en20te1r7)R. T1Ahi2sBw10o0r9k3w14as&s2u0p1p6oRr1teCd1Bin10p0a9r6t8b9y). tSh.eHB. awsaics Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Grant no. 2017R1A2B1009314 & 2016R1C1B1009689). S.H. was supported by Conflicts of Interest: The authors declare no conflict of interest.This work was supported by the Ajou University research fund. This work was supported by the Ministry of Trade, Industry and Energy (MOTIE, No. 10051565 & 20000512) and Korea Display Research Corporation (KDRC) support program for the development of future devices technology for display industry. This work was partially supported by the GRRC program of Gyeonggi province (GRRC AJOU 2016B03, Photonics-Medical Convergence Technology Research Center). This work was supported in part by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Grant no. 2017R1A2B1009314 & 2016R1C1B1009689). S.H. was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No.2019R1C1C1007629)
