二维硅基环形光子晶体异质结的偏振无关单向传输特性研究

To realize the one-way optical transmission, is a basic problem in optical integration. Silicon photonic crystal devices not only inherit the mature silicon process technology, but also have the ability to perfectly control the light. Therefore, optical diode based on silicon photonic crystal has become a research focus in the field. The one-way transmission of current optical diode is only for one polarization mode, which limits the application. Annular photonic crystals are expected to design a polarization-independent silicon optical diode. This project aims to construct a two-dimensional square-lattice silicon annular photonic crystal heterojunction, analyze the band diagram of the transverse electric and transverse magnetic modes, reveal the existing conditions of the directional band gap, verify the frequency range of one-way transmission for the two modes, and explore the mechanism on how the structural parameters control the common frequency range for one-way transmission; calculate the forward and backward transmission spectra using the finite-difference time-domain method, and obtain the conditions to realize the broad-band polarization-independent one-way transmission; tailor the direction and coupling region of the hetero-interface to reveal the optimizational design of the high-efficiency polarization-independent optical diode. These studies will provide a new way to more effectively apply silicon photonic crystal optical diode in photoelectric integration and all-optical communication.

实现光信号的单向传输，是全光集成领域中的一个基本问题。硅基光子晶体器件既继承了成熟的硅基加工技术，又兼具光子晶体完美控制光的能力，因此硅基光子晶体光二极管成为该领域的研究热点。当前光二极管仅对一种偏振模式进行单向传输，从而限制了其应用。基于环形光子晶体有望设计出偏振无关的硅基光二极管。本项目拟构建二维正方晶格硅基环形光子晶体异质结结构，分析横电模式及横磁模式的能带图，揭示方向带隙的存在条件，探明两种模式各自实现单向传输的频率范围，探究光子晶体结构参数对共有的单向传输频率范围的操纵机理；采用时域有限差分法计算异质结的正、反向透过谱，获取宽频带内偏振无关单向传输的实现条件；调控异质结界面的方位及界面耦合区结构，探寻高效的偏振无关光二极管的优化设计。这些研究为硅基光子晶体光二极管更有效地应用于光电集成及全光通讯提供了新的思路。

实现光信号的单向传输，是全光集成领域中的一个基本问题。硅基光子晶体器件既继承了成熟的硅基加工技术，又兼具光子晶体完美控制光的能力，因此硅基光子晶体光二极管成为该领域的研究热点。本项目为解决目前单一模式光二极管的缺憾，引入环形孔光子晶体，构建了硅基环形光子晶体异质结等结构，提出了多种可实现偏振无关单向传输的途径，设计出了单向传输效率高达45%的偏振无关光二极管。研究结果表明：两不同尺寸的空气环形光子晶体必须使得它们同时对横电及横磁模具有明显的方向带隙差异，由其构建的异质结结构才能实现显著的偏振无关单向传输特性；异质结界面的优化能有效提高其传输效率；具有抗反射层的三角形状空气环形光子晶体也可实现高效的偏振无关单向传输特性。这些研究成果为设计性能优异的全光二极管提供了新的思路，在未来全光集成芯片和全光通信网络中具有很大的应用潜力。