碳化硅纳米棒的表面声子极化激元调控

Manipulation of surface phonon polaritons in Si C nanorods

表面声子极化激元的频率一般在红外和太赫兹波段,在亚波长控制和调控方面有非常大的应用潜力,因此研究它们在纳米结构中的行为对减小器件尺寸是非常必要的.本文利用最新的扫描透射电镜电子能量损失谱技术,研究了碳化硅纳米棒的尺寸和形状效应.研究发现不同截面的纳米棒,其表面声子极化激元的频率和空间分布有很大不同.随着纳米棒直径减小,表面声子极化激元频率出现明显的红移,且倏逝场的分布范围更广.对于截面形状变化的纳米棒,倏逝场倾向于分布在截面面积较小的区域,理论模拟和实验结果都证实了这一点.因此,我们可以通过改变纳米棒的截面形状和尺寸来调控表面声子极化激元的频率和空间分布,设计新型的纳米尺寸的光子学器件.

Surface phonon polaritons(SPh Ps) are potentially very attractive for subwavelength control and manipulation of light at the infrared to terahertz wavelengths. Probing their propagation behavior in nanostructures is crucial to guide rational device design. Here, aided by monochromatic scanning transmission electron microscopy-electron energy loss spectroscopy technique, we measure the dispersion relation of SPh Ps in individual Si C nanorods and reveal the effects of size and shape. We find that the SPh Ps can be modulated by the geometric shape and size of Si C nanorods. The energy of SPh Ps shows redshift with decreasing radius and the surface optical phonon is mainly concentrated on the surface with large radius. Therefore, the fields can be precisely confined in specific positions by varying the size of the nanorod, allowing effective tuning at nanometer scale. The findings of this work are in agreement with dielectric response theory and numerical simulation, and provide novel strategies for manipulating light in polar dielectrics through shape and size control, enabling the design of novel nanoscale phononphotonic devices.