Many applications require colored surfaces while maximizing photons to pass through with no optical losses. As the perceived color depends on the spectral content and the number of reflected photons for each wavelength, it is necessary to consider not only the chromatic content but also the brightness. As a first application example, photovoltaic modules could see their acceptance in urban situations greatly improved if their color could be controlled while maximizing the number of photons used for energy conversion. In this case, it is important to limit light brightness to avoid glare when light coming from the sun is reflected directly. As another example, a colored and semi-transparent glass layer in the infrared could efficiently protect sensors while camouflaging them, such as lidar in automotive applications. We propose a theoretical study for multicolor applications, considering 2D partially etched grating waveguide structures that behave as a perfect broadband antireflection coating while the residual layer couples light in a waveguided mode in order to reflect only a particular photon band. This strategy allows to produce a large variety of colors and the use of non-absorbing materials avoids any optical loss. The width of the resonance peak is a crucial parameter for balancing brightness in multicolor applications. In the second part, we developed a method for a fast optimization of the geometrical parameters and we applied it to obtain the three primary colors with strong geometrical constraints, so that such structures could be manufactured in a single step by nano-imprint. Finally, we propose some improvements of these structures, in particular by reducing broadband reflection to obtain more saturated colors, or to improve the angular behavior of these structures.

中文翻译：

---

半透明纳米图案表面的颜色管理

许多应用都需要有色表面，同时要使光子通过时最大化而没有光学损失。由于感知的颜色取决于光谱含量和每个波长的反射光子数量，因此不仅要考虑色度含量，还要考虑亮度。作为第一个应用示例，如果可以控制光伏模块的颜色，同时最大化用于能量转换的光子数量，则光伏模块在城市环境中的接受度将大大提高。在这种情况下，重要的是限制光的亮度，以避免当来自太阳的光被直接反射时产生眩光。作为另一个示例，红外中的彩色半透明玻璃层可以有效地保护传感器，同时伪装它们，例如汽车应用中的激光雷达。我们提出一种针对多色应用的理论研究，考虑2D部分刻蚀的光栅波导结构，其表现为完美的宽带抗反射涂层，而剩余层以波导模式耦合光以仅反射特定的光子带。这种策略可以产生多种颜色，并且使用非吸收性材料可以避免任何光学损失。共振峰的宽度是在多色应用中平衡亮度的关键参数。在第二部分中，我们开发了一种用于快速优化几何参数的方法，并将其应用于获得具有强几何约束的三种原色，以便可以通过纳米压印一步一步制造此类结构。最后，我们建议对这些结构进行一些改进，