Pruszyńska-Karbownik Emilia, Jandura Daniel, Dems Maciej, Zinkiewicz Łukasz, Broda Artur, Gębski Marcin, Muszalski Jan, Pudiš Dušan, Suffczyński Jan, Czyszanowski Tomasz
Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland.
Department of Physics, Faculty of Electrical Engineering and Information Technology, University of Žilina, Žilina, Slovakia.
Nanophotonics. 2023 Aug 29;12(18):3579-3588. doi: 10.1515/nanoph-2023-0283. eCollection 2023 Sep.
Highly reflective mirrors are indispensable components in a variety of state-of-the-art photonic devices. Typically used, bulky, multi-layered distributed Bragg (DBR) reflectors are limited to lattice-matched semiconductors or nonconductive dielectrics. Here, we introduce an inverted refractive index-contrast grating (ICG) as compact, single-layer alternative to DBR. In the ICG, a subwavelength one-dimensional grating made of a low-refractive-index material is implemented on a high-refractive-index cladding. Our numerical simulations show that the ICG provides nearly total optical power reflectance for the light incident from the side of the cladding whenever the refractive index of the grating exceeds 1.75, irrespective of the refractive index of the cladding. Additionally, the ICG enables polarization discrimination and phase tuning of the reflected and transmitted light, the property not achievable with the DBR. We experimentally demonstrate a proof-of-concept ICG fabricated according to the proposed design, using the technique of sub-µm 3D laser lithography in which thin stripes of IP-Dip photoresist are micro-printed on a Si cladding. This one-step method avoids laborious and often destructive etching-based procedures for grating structuration, making it possible to implement the grating on any arbitrary cladding material.
高反射镜是各种先进光子器件中不可或缺的组件。通常使用的笨重多层分布式布拉格（DBR）反射器仅限于晶格匹配的半导体或非导电介质。在此，我们引入一种倒置折射率对比度光栅（ICG），作为DBR的紧凑单层替代方案。在ICG中，由低折射率材料制成的亚波长一维光栅被应用于高折射率包层上。我们的数值模拟表明，只要光栅的折射率超过1.75，无论包层的折射率如何，ICG都能为从包层一侧入射的光提供几乎全光功率反射率。此外，ICG能够对反射光和透射光进行偏振鉴别和相位调谐，这是DBR无法实现的特性。我们通过亚微米3D激光光刻技术，在硅包层上微打印IP-Dip光刻胶细条纹，实验展示了根据所提出设计制造的概念验证ICG。这种一步法避免了用于光栅结构化的费力且通常具有破坏性的基于蚀刻的工艺，使得在任何任意包层材料上实现光栅成为可能。
