Pal Debapriya, López Toni, Koenderink A Femius
Department of Physics of Information in Matter and Center for Nanophotonics, NWO-I Institute AMOLF, Science Park 104, NL 1098XG Amsterdam, The Netherlands.
Lumileds Germany GmbH, Philipsstr. 8, D-52068 Aachen, Germany.
ACS Nano. 2025 Jan 14;19(1):1238-1250. doi: 10.1021/acsnano.4c13472. Epub 2024 Dec 23.
Phosphor-converted micro-light emitting diodes (micro-LEDs) are a crucial technology for display applications but face significant challenges in light extraction because of the high refractive index of the blue pump die chip. In this study, we design and experimentally demonstrate a nanophotonic approach that overcomes this issue, achieving up to a 3-fold increase in light extraction efficiency. Our approach involves engineering the local density of optical states (LDOS) to generate quasi-guided modes within the phosphor layer by strategically inserting a thin low-index spacer in combination with a metasurface for mode extraction. We demonstrate the trade-offs between blue light pumping, LDOS enhancement at the converted emission wavelength, and radiation pattern control using a stratified system solver for dipole emission. Experimentally, the integration of plasmonic antennas and a silica spacer resulted in a 3-fold overall brightness enhancement, with nearly a 4-fold increase in forward emission. This nanophotonic metasurface waveguide design is a critical advancement for producing bright, directional micro-LEDs, particularly in augmented/virtual reality (AR/VR) devices and smartwatch displays, without the need for bulky secondary optics or reflectors.
磷光转换微发光二极管（微型发光二极管）是显示应用中的一项关键技术，但由于蓝色泵浦芯片的高折射率，在光提取方面面临重大挑战。在本研究中，我们设计并通过实验证明了一种纳米光子学方法，该方法克服了这一问题，实现了高达三倍的光提取效率提升。我们的方法包括通过策略性地插入薄的低折射率间隔层并结合用于模式提取的超表面，来设计光学态的局部密度（LDOS），从而在磷光层内产生准导模。我们使用分层系统求解器来分析偶极发射，展示了蓝光泵浦、转换发射波长处的LDOS增强以及辐射方向图控制之间的权衡。实验表明，等离子体天线和二氧化硅间隔层的集成使整体亮度提高了三倍，正向发射增加了近四倍。这种纳米光子超表面波导设计是生产明亮、定向微型发光二极管的一项关键进展，特别是在增强/虚拟现实（AR/VR）设备和智能手表显示屏中，无需笨重的二次光学元件或反射器。
