人工微结构界面调控热光辐射的基础理论、实验技术与器件应用研究

In this project, we will study the manipulation of thermal radiation utilizing artificial optical nanostructures and metamaterials. Thermal radiation is one of most efficient energy transfer and propagation ways. However, the practical potential of thermal radiation is serious hindered by undesired natures of spontaneous emission, i.e., low efficiency, stochastic properties in polarization, space or time coherence, etc. In this project, we will try to solve these problems and improve the technological application potentials by employing metameterials and artificial nanophotonic structures to control the emission of thermal photons. We will mainly pursue a highest thermal emission efficiency that could substantially break Plancket's blackbody thermal emission limit and deeply explore the related fundamental theory, experimental skills and device applications. In the first part, we will try to find the way to elaborately solve the stochastic Maxwell's equations complicated with arrays of subwavelength resonant elements. From these mathematical methods, we will explore to the practicable approaches to manipulate thermal photons using metamaterials and nanostructured infrared plasmonic materials (such as graphene). As the second part of this project, we will meet the challenges to carry out the experimental works that will be very demanding for near-field heat transfer measurement, especially incorporating artificial structures, which is currently a still empty field. New phenomena may be also expected in extreme near-field conditions. The third part of this proposal is to explore the near-field heat transfer scheme for practical applications primarily for thermophotovoltaics and thermodiode devices. We will apply the structural designs to push the development of these promising new-energy technologies toward real application ends.

本项目将研究运用人工微结构从亚波长尺度上对热激发光子物理过程进行深度调控，以期获得远超普朗克黑体极限的热辐射效率或对辐射光波谱、方向、相干度等其它核心参数的极大控制，为大幅提升现有热辐射技术水平或产生新的应用创造有利条件。我们将从随机电磁波方程出发，来研究亚波长结构调控热光辐射的作用机理与物理过程，建立复杂体系中热辐射系数的准确数学分析方法，设计构造人工微结构体系以获得各种热辐射异常调制效果。在理论与数值研究基础上，我们将积极展开近场热辐射等关键实验技术研究，填补此方面空白，并进一步深入探索极近场情形下随机倏逝波光子与微纳结构的界面作用规律。之后我们将研究利用近场热辐射技术来设计新型热光伏与热整流器件，以大幅提高这些新能源器件的工作效率与技术应用前景。本项目极有望在热辐射调控机理与应用上取得较大突破，获得有影响力原创性研究成果，为人工微结构光学与热辐射研究发展做出贡献。

热辐射作为一种简单有效的能量转换与传递方式，其全面发展一直以来受限于其较低的能量传递效率，而自发辐射光子在极化、辐射方向及相干度等重要参数上的无规性也大大制约了它的光源应用范围。研究改进和大幅提高这些性能参数是当前光学领域研究的一项重要课题，具有很大的理论意义与实际应用价值。.本项目深入开展了人工介质、等离激元与相变材料等对于热光子辐射与作用过程的调控新机制研究，提出了热辐射在整流、制冷与能量收集上的新型应用器件，开展并完成了部分器件的实验测试与功能验证工作，充分展示了光场调控在热辐射基础与应用上的发展前景。项目揭示了等离激元作用下的热光子近场热传输规律，证实了经典热涨落理论对二维材料的适用性，也给出了人工结构等效介质理论在近场下的实用性条件；提出了基于变换光学理论的热辐射激发与传输控制新方法，拓展了超表面界面调控在光子辐射与接收上的新方法与新理论。在实验上，根据测量目标物的不同情况，原创了多套近场热流测试方案，包含磁吸式大面积测试系统、全光微结构测试方案与变间距极近场测试技术。利用它们完成了等离激元、人工结构与二维材料异质结构间的近场热流测试，观测到了近场超普朗克黑体辐射现象。项目提出了石墨烯-硅异质结与超薄多晶硅两种新型热光伏体系结构，获得了优异的热光电转化性能；大力发展了融合辐射调控的磁、声、电磁波与光的多物理场协同隐身技术；发展了基于辐射调控的无源辐射制冷与控温技术。