论文标题
$α$ -MOO3的宽光谱可持续性和双曲线声子Polariton的可控激发
Broad-Spectral-Range Sustainability and Controllable Excitation of Hyperbolic Phonon Polaritons in $α$-MoO3
论文作者
论文摘要
在异栓性三氧化物三氧化物（$α$ -MOO3）中，双曲声子偏振子（HPHP）显示出平面内的双曲线，出色的波长压缩和超长的终身，因此在纳米光量应用中具有巨大的潜力。但是，由于实验表征的挑战，它在远红外（FIR）范围内的极性响应一直未被开发。在这里，使用扫描透射电子显微镜（STEM）中的单色电子能量损失光谱（EEL），我们在中红外（MIR）和FIR频率中以$α$ -MOO3的价格探测HPHP，并将其行为与显微结构和方向相关联。我们发现，低结构的对称性会导致各种声子模式和多个RESTSTRAHLEN带（RBS）在广泛的光谱范围内（超过70 MeV）和不同的方向（55-63 MeV和119-125 MEV沿B轴，沿B轴，68-106 MEV沿C轴沿C轴沿轴沿A轴沿C轴68-106 MEV）。这些HPHP可以通过控制Swift电子的方向有选择地激发。这些发现在纳米光子和光电应用中提供了新的机会，例如定向光传播，超lens和传热。
Hyperbolic phonon polaritons (HPhPs) in orthorhombic-phase molybdenum trioxide ($α$-MoO3) show in-plane hyperbolicity, great wavelength compression and ultra-long lifetime, therefore holding great potential in nanophotonic applications. However, its polaritonic response in the far-infrared (FIR) range has long remained unexplored due to challenges in experimental characterization. Here, using monochromated electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM), we probe HPhPs in $α$-MoO3 in both mid-infrared (MIR) and FIR frequencies and correlate their behaviors with microstructures and orientations. We find that low-structural symmetry leads to various phonon modes and multiple Reststrahlen bands (RBs) over a broad spectral range (over 70 meV) and in different directions (55-63 meV and 119-125 meV along b axis, 68-106 meV along c axis, 101-121 meV along a axis). These HPhPs can be selectively excited by controlling the direction of swift electrons. These findings provide new opportunities in nanophotonic and optoelectronic applications such as directed light propagation, hyperlenses and heat transfer.
