Chen I-Te, Premnath Vijay Anirudh, Chang Chih-Hao
Opt Lett. 2024 Feb 15;49(4):1093-1096. doi: 10.1364/OL.516147.
Dielectric mirrors based on Bragg reflection and photonic crystals have broad application in controlling light reflection with low optical losses. One key parameter in the design of these optical multilayers is the refractive index contrast, which controls the reflector performance. This work reports the demonstration of a high-reflectivity multilayer photonic reflector that consists of alternating layers of TiO films and nanolattices with low refractive index. The use of nanolattices enables high-index contrast between the high- and low-index layers, allowing high reflectivity with fewer layers. The broadband reflectance of the nanolattice reflectors with one to three layers has been characterized with peak reflectance of 91.9% at 527 nm and agrees well with theoretical optical models. The high-index contrast induced by the nanolattice layer enables a normalize reflectance band of Δλ/λ of 43.6%, the broadest demonstrated to date. The proposed nanolattice reflectors can find applications in nanophotonics, radiative cooling, and thermal insulation.
基于布拉格反射和光子晶体的介质镜在控制光反射且光损耗较低方面有着广泛应用。这些光学多层膜设计中的一个关键参数是折射率对比度，它控制着反射器的性能。这项工作报道了一种高反射率多层光子反射器的演示，该反射器由交替的TiO薄膜层和低折射率纳米晶格组成。纳米晶格的使用使得高折射率层和低折射率层之间具有高折射率对比度，从而能用更少的层数实现高反射率。一到三层纳米晶格反射器的宽带反射率已得到表征，在527 nm处的峰值反射率为91.9%，与理论光学模型吻合良好。纳米晶格层引起的高折射率对比度实现了归一化反射带宽Δλ/λ为43.6%，这是迄今为止所展示的最宽的带宽。所提出的纳米晶格反射器可应用于纳米光子学、辐射冷却和热绝缘领域。
