中红外可直调型掺杂半导体超材料光学特性调控机理研究

Metamaterials can exhibit some optical properties, which can’t be observed in nature and can de designed into what we desire, can significantly improve performances of traditional optical components and devices, and show great prospects in mid-infrared applications. Metals as the composition of almost metamaterials reported have high losses, and their optical properties can’t be tuned. As a result, extraordinary optical properties of metamaterials can hardly be fully employed and effectively regulated, severely hampered developments and applications of mid-infrared components and devices based on metamaterials. In this proposal, a direct-control method strategy of electromagnetic properties with doped-semiconductor metamaterials is used to reduce the electromagnetic loss and enhance the performance of tunable metamaterials. The distribution and motion state of carriers in subwavelength semiconductors in the mid-infrared range, the mechanism of electromagnetic resonances, as well as the effect of external fields on carriers in doped-semiconductor metamaterials and its mechanisms are investigated in detail. The simulation and experimental studies on optical characteristics and tunable performances of mid-infrared doped-semiconductor metamaterials are performed as well. The implementation of this project is of great importance for the theory and technology development of structure designs and modulations of electromagnetic characteristics of metamaterials, and the expected results can provide a theoretical guidance to the design of high-performance and tunable metamaterial optical elements and devices (such as optical switches and modulators).

超材料的光学性质非同寻常且可自由设计，能显著提升传统光学元器件的性能，在中红外应用领域已显示出诱人的前景。金属作为当前主流超材料的构成成分，其自身强烈的光学损耗和物理性质不可控性，导致超材料光学特性的充分发挥和高效调控变得异常困难，严重阻碍了中红外超材料元器件的开发与应用。本项目采用掺杂半导体超材料，结合电磁特性直调策略，降低超材料元器件电磁损耗，提升其调控性能。研究中红外电磁波作用下，亚波长结构掺杂半导体内部载流子分布规律与运动状态特性，在此基础上探索掺杂半导体超材料结构单元电磁共振形成机理，并进一步研究外部调控场对掺杂半导体超材料内部载流子共振运动的影响规律及作用机制，同时对其光学特性和调控性能进行实验研究。本项目研究对超材料的结构设计与电磁特性调控的理论和技术的发展均有重要意义，同时为高性能、电磁可调控型超材料元器件（如光开光、调制器等）设计提供理论技术指导。

超材料的光学性质非同寻常且可自由设计，能显著提升传统光学元器件的性能，在中红外应用领域已显示出诱人的前景。金属作为当前主流超材料的构成成分，其自身强烈的光学损耗和物理性质不可控性，导致超材料光学特性的充分发挥和高效调控变得异常困难，严重阻碍了中红外超材料元器件的开发与应用。本项目研究了中红外半导体超材料电磁共振特性，以及外部调控场对亚波长半导体超材料单元电磁共振运动影响机制。研究结果显示，电磁超材料共振波长（或共振频率）与自由载流子有效路径长度密切相关，共振强度决定于超材料单元内耦合电场引起的绝对电势差。例如，相同物质和线长构建的各结构形状超材料单元，其共振波长（或共振频率）基本一致，且I型结构单元超材料电磁共振强度更强。建立了中红外电磁波下亚波长掺杂半导体自由载流子状态参数模型，阐明了外部调控场对掺杂半导体超材料内部载流子共振运动的调控规律。例如，所设计二维可调控型半导体超材料调制器可实现线性调制，调制深度可达42%；三维层状可调控型中红外半导体超材料有效折射率变化范围达到10。本项目为高性能、电磁可调控型超材料元器件（如光开光、调制器等）设计提供了理论技术指导，为超材料的结构设计与半导体超材料电磁特性调控奠定了重要基础。在该项目资助下，发表带有基金号标注的论文8篇，获授权相关发明专利3项，培养硕士1名。