Liu Mengqi, Zhao Changying
Institute of Engineering Thermophysics, MOE Key Laboratory for Power Machinery and Engineering, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
ACS Appl Mater Interfaces. 2021 Jun 2;13(21):25306-25315. doi: 10.1021/acsami.1c05462. Epub 2021 May 20.
Engineering wavelength-selective thermal emission is a promising technology associated with several advanced applications, including thermal imaging, gas sensing, far/near-field thermophotovoltaics, and so on. However, the majority of reported approaches suffer from low -factor emission due to intrinsic loss of metallic components or rely on thick structures like multilayers to ensure unitary emissivity, making it challenging to design compatible high- narrowband emitters. In this work, we propose a mechanism to tailor thermal emission by taking advantage of optically induced high-order antiferromagnetic (AFM) resonances in a simple subwavelength 2D Si nanobar. Such AFM modes, stemmed from hybrid magnetic dipoles and high-order Fabry-Perot modes, exhibit both pronounced resonant responses and superior light confinement ability. We first reveal its essential roles in ultranarrowband emission control with a sharp ( ∼ 400) and near-perfect emissivity available. Especially, the measured angle-resolved emission spectra further indicate that the AFM-induced emission peak, being nearly immune to changes of nanogratings' periods and incident angle, is able to be flexibly engineered in a wide waveband by merely tuning the width-to-height ratio of nanobars. Our work provides a promising strategy to design extremely high- thermal emitters possessing robust narrowband performance, large spectral tunability and desirable compatibility with advanced planar nanofabrication techniques, which will be more favorable in practice compared with metallic counterparts. Besides, we anticipate that, the revealed mechanism of high-order AFM modes can also stimulate advanced applications in diverse research communities including but not limited to multipolar physics, nonlinear nano-optics, energy harvesting, etc.
工程化波长选择性热发射是一项很有前景的技术，与多种先进应用相关，包括热成像、气体传感、远/近场热光伏等等。然而，大多数已报道的方法由于金属部件的固有损耗而存在低发射率问题，或者依赖多层等厚结构来确保单一发射率，这使得设计兼容的高窄带发射器具有挑战性。在这项工作中，我们提出了一种机制，通过利用简单的亚波长二维硅纳米棒中的光诱导高阶反铁磁（AFM）共振来调整热发射。这种源于混合磁偶极子和高阶法布里 - 珀罗模式的AFM模式，既表现出明显的共振响应，又具有卓越的光限制能力。我们首先揭示了其在超窄带发射控制中的关键作用，可实现尖锐（约400）且接近完美的发射率。特别是，测量的角度分辨发射光谱进一步表明，AFM诱导的发射峰几乎不受纳米光栅周期和入射角变化的影响，仅通过调整纳米棒的宽高比就能在很宽的波段内灵活设计。我们的工作提供了一种很有前景的策略，用于设计具有强大窄带性能、大光谱可调性以及与先进平面纳米制造技术良好兼容性的极高热发射器，与金属同类产品相比，在实际应用中更具优势。此外，我们预计，所揭示的高阶AFM模式机制还能推动包括但不限于多极物理、非线性纳米光学、能量收集等不同研究领域的先进应用。
