Highly Confined and Tunable Hyperbolic Phonon Polaritons in Van Der Waals Semiconducting Transition Metal Oxides
Highly Confined and Tunable Hyperbolic Phonon Polaritons in Van Der Waals Semiconducting Transition Metal Oxides
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范德华半导体过渡金属氧化物中的高度受限和可调谐双曲声子极化子
DOI：
10.1002/adma.201705318
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发表时间：
2018-03-27
影响因子：
29.4
通讯作者：
Xu, Ningsheng
中科院分区：
文献类型：
--
作者：
Zheng, Zebo;Chen, Jianing;Xu, Ningsheng
二维货车瓦（vdW）层状极性晶体维持声子极化激元（PhPs）为中红外到太赫兹范围内的基础研究和光电应用开辟了新的途径。到目前为止，2D vdW晶体与PhPs的实验证明，只有在六方氮化硼（hBN）板坯。对于光电和有源光子应用，具有可调电荷、有限电导率和适度带隙的半导体是优选的。在这里，证明了低损耗和低电磁场限制在半导体VDW α-MoO 3的PhPs。α-MoO 3在中红外范围内支持强双曲线PhPs，阻尼率低至0.08。电磁约束可以达到接近λ 0/120，这可以通过改变α-MoO 3 2D薄片的厚度来定制。此外，通过金属离子嵌入策略实现了对PhPs的空间控制。结果表明，α-MoO 3作为一个新的平台，用于研究双曲型PhPs的可调谐性，使可切换的中红外纳米光子器件。
2D van der Waals (vdW) layered polar crystals sustaining phonon polaritons (PhPs) have opened up new avenues for fundamental research and optoelectronic applications in the mid-infrared to terahertz ranges. To date, 2D vdW crystals with PhPs are only experimentally demonstrated in hexagonal boron nitride (hBN) slabs. For optoelectronic and active photonic applications, semiconductors with tunable charges, finite conductivity, and moderate bandgaps are preferred. Here, PhPs are demonstrated with low loss and ultrahigh electromagnetic field confinements in semiconducting vdW alpha-MoO3. The alpha-MoO3 supports strong hyperbolic PhPs in the mid-infrared range, with a damping rate as low as 0.08. The electromagnetic confinements can reach approximate to lambda 0/120, which can be tailored by altering the thicknesses of the alpha-MoO3 2D flakes. Furthermore, spatial control over the PhPs is achieved with a metal-ion-intercalation strategy. The results demonstrate alpha-MoO3 as a new platform for studying hyperbolic PhPs with tunability, which enable switchable mid-infrared nanophotonic devices.