介质加载表面等离激元的近场光学观测

Dielectric-loaded surface plasmon polariton studied by using scanning near-field optical microscopy

利用扫描近场光学显微术(SNOM),观测并分析了基于银膜衬底上CdS纳米带的介质加载表面等离激元(Dielectric-loaded Surface Plasmon Polariton,DLSPP)的激发现象。通过SNOM可以观察到纳米带不同位置的光致荧光光谱峰位有30meV的红移量。利用Franz-Keldysh效应可以很好地解释能量红移的产生。有限时域差分法的模拟结果进一步验证了实验中观测的现象。这种DLSPP的激发结构,对于光子集成电路及基于等离激元的微纳器件波导有实际意义。

We observed the excitation of dielectric-loaded surface plasmon polariton （DLSPP） by a CdS nano-stripe placed on an Ag layer by using scanning near-field optical microscopy （SNOM）. A 30 meV spectroscopic rod-shift of photoluminescence （PL） was observed at different positions of the stripe by SNOM, which can be explained as the result of Franz-Kelysh effect. The observations of the near-field optical images and spectroscopic data were confirmed by Finite Difference Time Domain （FDTD） calculations. This DLSPP excitation structure is important for the implementation of photonic integrated circuits as well as the optical guiding modes in piasmonic devices.