Optimization of waveguide components for symmetric-Mach-Zehnder-type all-optical switch based on photonic crystals

二维光子晶体平板波导是未来高速光子网络系统中全光集成电路的理想选择。为了开发高功能器件，波导元件的设计在PC技术中至关重要。拓扑优化（TO）方法是一种高效的优化算法，可以为定制具有预期功能的波导元件创建所需的材料分布。我们采用TO方法设计了空气桥型二维PC板的波导元件。通过制作基于gaas的PC板，我们成功地证明了TO设计方法对实现具有与直波导相当的宽带宽和透射率的相交，弯曲，定向耦合器和y结波导的显著贡献。这一结果对于光子数字处理器以及基于二维PC平板波导的超快速全光器件的发展是令人鼓舞的。

Two dimensional (2D) photonic crystal (PC) slab waveguides are attractive candidate to develop all-optical integrated circuits for future high-speed photonic network system. For developing high-functionality devices, the design of waveguide components is crucial in the PC technology. A topology optimization (TO) method is an efficient optimization algorithm that creates desired material distribution for customizing waveguide components with expected functionality. We employed the TO method to design waveguide components in air-bridge-type, 2D PC slabs. Bu fabricating GaAs-based PC slabs, we successfully demonstrated that the TO design method has remarkably contributed to achievement of intersection, bend, directional coupler and Y-junction waveguides with wide bandwidth and transmittance comparable to that of the straight waveguide. The results are encouraging for the development of a photonic digital processor as well as ultra-fast, all-optical devices based on 2D PC slab waveguides.