The extinction is defined as 1-T, with T being the transmittance that obtained by normalizing the output power at the top boundary to that of the background field. To evaluate the extinction and near-field enhancement effects of the guided modes excited in polymer layer, the system is excited by a plane wave under normal incidence. Optical response of the nanoparticle array-waveguide system can be obtained by simulating a unit cell in the computational domain, with Floquet periodic boundary employed for four lateral boundaries and perfectly matched layers (PML) in the vertical (z) direction. All calculations are performed in COMSOL Multiphysics® 5.1 with the wave optics module. Optical constants of crystalline Si and Al are taken from Palik. For its plasmonic counterpart used for comparison, an aluminum nanopillar array is embedded in the polymer layer with the same structural parameters. In practice, the polymer layer is doped with dye molecules, rare-earth ions or QDs, acting as a color-converting layer to combine with the blue LED. The square or hexagonal Si nanopillar array is embedded in a polymer waveguide layer (n=1.59) and deposited on a glass silica substrate (n=1.46), constituting a nanoparticle array-waveguide system. These performances make the silicon nanopillar arrays have potential application in light converter for efficient white LEDs.Ī schematic of the proposed structure is presented in Fig. By investigating theoretically the guided mode caused by the nanopillar array-waveguide system, we demonstrate that the silicon nanopillar arrays enable larger near-field enhancement and more efficient photons emission property than the plasmonic counterparts.
![array comsol 5.1 array comsol 5.1](https://media.springernature.com/original/springer-static/image/chp%3A10.1007%2F978-3-030-58058-2_5/MediaObjects/501879_1_En_5_Fig3_HTML.png)
Here, we propose a design of white LEDs that combining dielectric silicon nanopillar array in the color-converting layer. Plasmonic metallic nanostructures have been demonstrated an effective way to enhance the light emission efficiency in LEDs.