近日，荷兰原子与分子物理研究所的Ewold Verhagen及其研究团队取得一项新进展。经过不懈努力，他们利用合成应变诱导的伪磁场观察到光子晶体中的朗道能级和手性边缘态。相关研究成果已于2024年4月23日在国际知名学术期刊《自然—光子学》上发表。

本文通过对二维光子晶体晶格施加工程应变，成功在实验中实现了二维光子晶体中的伪磁场。这一发现与应变石墨烯的类似效应相呼应，即在离散能量下产生了平带朗道能级。研究人员利用远场光谱技术，深入研究了硅光子晶体在电信波长下这些态的空间和光谱特性。研究人员利用光子晶体的设计自由度，实现了相反的伪磁场域，并观察了它们界面处的手性边缘态。他们发现，尽管应变诱导态的相位与辐射连续体相匹配，但仍能获得非常高的质量因子。

此外，与平带相关的高密度态和高简并特性，为增强光与物质的相互作用提供了广泛的前景，并说明了伪磁场在纳米光子领域的广阔潜力。因此，这项工作为控制片上光场和辐射光场提供了新的设计原则。

据悉，光子晶体中光的传播和定位控制具有广泛的应用前景，涵盖传感、片上路由、激光以及量子光-物质界面等领域。尽管在电子晶体中，磁场能有效诱导多种独特现象，但鉴于光子不带电的特性，需寻求替代方法来在纳米尺度上实现类似的光子控制。

附：英文原文

Title: Observation of Landau levels and chiral edge states in photonic crystals through pseudomagnetic fields induced by synthetic strain

Author: Barczyk, Ren, Kuipers, L., Verhagen, Ewold

Issue&Volume: 2024-04-23

Abstract: Control over light propagation and localization in photonic crystals offers wide applications ranging from sensing and on-chip routing to lasing and quantum light–matter interfaces. Although in electronic crystals, magnetic fields can be used to induce a multitude of unique phenomena, the uncharged nature of photons necessitates alternative approaches to bring about similar control over photons at the nanoscale. Here we experimentally realize pseudomagnetic fields in two-dimensional photonic crystals through engineered strain of the lattice. Analogous to strained graphene, this induces flat-band Landau levels at discrete energies. We study the spatial and spectral properties of these states in silicon photonic crystals at telecom wavelengths with far-field spectroscopy. Moreover, taking advantage of the photonic crystal’s design freedom, we realize domains of opposite pseudomagnetic field and observe chiral edge states at their interface. We reveal that the strain-induced states can achieve remarkably high quality factors despite being phase matched to the radiation continuum. Together with the high density of states and high degeneracy associated with flat bands, this provides powerful prospects for enhancing light–matter interactions, and illustrates the broad potential of psdeudomagnetic fields in the nanophotonic domain. This work, thus, establishes a new design principle to govern both on-chip and radiating light fields.

DOI: 10.1038/s41566-024-01412-3

Source: https://www.nature.com/articles/s41566-024-01412-3