Active tuning of anisotropic phonon polaritons in natural van der Waals crystals with negative permittivity substrates and its application in energy transport
负介电常数衬底的自然范德华晶体中各向异性声子极化子的主动调谐及其在能量传输中的应用
負誘電率基板の自然vanderWaals結晶における異方性フォノンポーラロンの能動同調とエネルギー輸送への応用
음개전 상수 라이닝의 자연 범덕화 결정체 중 각방향 이성 성자 극화자의 능동 조화 및 에너지 전송에서의 응용
Ajuste activo de polarones de Fonón isotrópicos en cristales van der Waal naturales con sustratos de constante dieléctrica negativa y sus aplicaciones en la transmisión de energía
Accord actif des polarisons phonons anisotropes dans les cristaux naturels de Van der Waals pour substrats à permittivité diélectrique négative et leur application à la transmission d'énergie
активная настройка анизотропных фононных поляризаторов в кристаллах Ван дер Ваальта на подложке с отрицательной диэлектрической постоянной и их применение в передаче энергии
Shuo Chen 陈硕 ¹ ², Xiaohu Wu 吴小虎 ², Ceji Fu 符策基 ¹
¹ LTCS and Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China
中国 北京 北京大学工学院 力学与工程科学系 湍流与复杂系统国家重点实验室
² Shandong Institute of Advanced Technology, Jinan 250100, China
中国 济南 山东高等技术研究院
Phonon polaritons (PhPs) exhibit directional in-plane propagation and ultralow losses in van der Waals (vdW) crystals, offering new possibilities for controlling the flow of light at the nanoscale. However, these PhPs, including their directional propagation, are inherently determined by the anisotropic crystal structure of the host materials.
Although in-plane anisotropic PhPs can be manipulated by twisting engineering, such as twisting individual vdW slabs, dynamically adjusting their propagation presents a significant challenge. The limited application of the twisted bilayer structure in bare films further restricts its usage.
In this study, we present a technique in which anisotropic PhPs supported by bare biaxial vdW slabs can be actively tuned by modifying their local dielectric environment. Excitingly, we predict that the iso-frequency contour of PhPs can be reoriented to enable propagation along forbidden directions when the crystal is placed on a substrate with a moderate negative permittivity.
Besides, we systematically investigate the impact of polaritonic coupling on near-field radiative heat transfer (NFRHT) between heterostructures integrated with different substrates that have negative permittivity. Our main findings reveal that through the analysis of dispersion contour and photon transmission coefficient, the excitation and reorientation of the fundamental mode facilitate increased photon tunneling, thereby enhancing heat transfer between heterostructures.
Conversely, the annihilation of the fundamental mode hinders heat transfer. Furthermore, we find the enhancement or suppression of radiative energy transport depends on the relative magnitude of the slab thickness and the vacuum gap width. Finally, the effect of negative permittivity substrates on NFRHT along the [001] crystalline direction of α-MoO3 is considered.
The spectral band where the excited fundamental mode resulting from the negative permittivity substrates is shifted to the first Reststrahlen Band (RB 1) of α-MoO3 and is widened, resulting in more significant enhancement of heat flux from RB 1. We anticipate our results will motivate new direction for dynamical tunability of the PhPs in photonic devices.
