异构光子晶体任意偏振态光单向高透射机制研究

A photonic diode that realizes unidirectional transmission of light becomes a key component of a quantum computer because it can perform logic operations. At present, micro-nanoscale photonic diodes based on spatial inversion asymmetry are limited by material loss, bandgap width and band matching, and have low forward transmittance, low contrast ratio, narrow bandwidth and only work for a specific polarization state. This paper proposes a theoretical model of unidirectional transmission of light based on generalized total reflection theory, and designs photonic crystal heterostructure that satisfies generalized total reflection conditions. We use theoretical analysis and numerical methods to calculate energy band structure, equal-frequency contour, forward transmittance, contrast ratio, and electric field distribution, illustrating the generalized total reflection mechanism; demonstrating the relationship between amplitude, phase, and electric field spatial distribution of arbitrary polarization states (including linear, circular, and elliptical polarizations) and two orthogonal polarization states (TE and TM).It is to find out the mechanism of the band gap interconnection to achieve a wide working wavelength range and to reveal the role of self-collimation effect and the wave guide effect of photonic crystal structures in improving the forward transmittance of the light wave. It is to optimize the lattice structure parameters and finally achieve a high forward transmittance and high contrast ratio of unidirectional transmission of arbitrary polarization states in a broad wavelength range. This strategy provides a new way for implementing integrated photonic diodes and has scientific value and practical significance.

单向传输光子二极管因可实现逻辑运算已成为量子计算机的关键部件。目前基于空间反演不对称性设计的微纳尺度光子二极管受材料损耗、带隙宽度和能带匹配等限制，存在正向透射率低，对比度低，带宽窄及工作于特定偏振态等问题，制约了光子集成的发展。本项目创新性地提出广义全反射异构光子晶体实现任意偏振态光单向高透射理论模型。选择可集成材料硅设计异质同构和异质异构光子晶体，采用理论分析并数值方法模拟能带结构、等频图、正向透射率、对比度和电场分布，说明广义全反射工作机理；阐明任意偏振态（包括线偏振，圆偏振，及椭圆偏振）与两个正交偏振态（TE和TM）的振幅，相位和电场空间分布之间的关联；探明能带交叠实现宽工作带宽的机理；揭示晶体结构自准直效应和导波效应提高光波正向透射率的机制，优化晶格参数，最终实现任意偏振态的高正向透射率和高对比度的单向传输，为实现集成化光子二极管提供理论依据，对量子计算具有科学价值和现实意义。

该项目针对目前微纳尺度光子二极管的设计存在工作带宽窄、透射对比度有待提高、工作限于特定偏振态等问题，深入探索了基于全反射原理的硅基异构光子晶体对任意线偏振光的调控机制，建立了光子晶体带宽拓宽和结构透射率提高的有效方案，探究了自准直效应和导波效应提高光波正向耦合效率的物理机理，研究了拓扑光子晶体提升工作带宽度的有效途径，为光子晶体光子二极管在光子芯片集成和量子计算等方面的应用提供了理论依据。取得如下成果：.（1）设计工作区域在光通信波段的二维异构光子晶体的结构，可实现任意线偏振光，椭圆偏振光与圆偏振光的宽带宽、高透射对比度的单向传输，解决现有光子二极管设计工作带宽窄、偏振选择限制等问题。研究光子晶体结构自准直效应在提高光波正向耦合效率的机制，为优化晶格结构参数实现高透射可集成单向传输光子二极管提供理论依据。.（2）研究光子晶体的缺陷导波效应对异构光子晶体中光波传输方向的作用，结合全反射界面实现了TE/TM线偏振光与圆偏振光的高透射对比度单向传输。为了降低结构设计的复杂性，采用不同的几何形状与晶格排列分别提出了硅基/六方氮化硼基在光通信波段/可见光波段的光子二极管设计，可应用于其他波段单向传输器件的设计。.（3）通过引入拓扑光子晶体的自旋谷锁定效应可实现圆偏振光在光通信波段与可见光波段的单向传输，对工作带宽的拓宽与正向透射率的提高有很大作用。基于能谷光子晶体的边缘态单向传输特性，构建拓扑波分复用器与环形谐振器设计，研究结构参数对工作范围的影响，为构建高速率、高密度可集成光子芯片打下坚实的基础。.项目研究期间，发表期刊论文17篇，其中SCI收录13篇；申请发明专利21项，其中已授权11项；培养博士生1人，硕士生14人。