表面等离激元（SPP）是一种在金属和介质的界面上传播的表面光波模式，由于光场的高度局域，金属表面的微弱变化都将显著地影响SPP的传播。本项目将研究在金属波导中引入时间调制，导致SPP在传播过程中发生非弹性散射的频率变化规律。具体内容将主要从以下几个方面展开：（1）设计新型表面等离激元波导，增加对SPP的调制强度；（2）理论分析并数值模拟SPP在周期和非周期时间调制波导中SPP的传播；（3）设计基于时间调制表面等离激元波导的有源纳米光子器件。通过本项目的研究，将揭示时间调制SPP的频率变化与介质受到空间调制产生的离散衍射现象之间的内在关联，为设计有源光子器件提供一种新的方案。本项目的研究成果将在设计下一代基于表面等离激元的超快、低损耗、高集成度有源光子器件，如调制器，频率转换器、超快光开关等方面有着广泛的应用前景。

Surface plasmon polariton (SPP) is a kind of surface mode that can propagate at the interface of metal and dielectric. Due to its strongly confined field, the SPP mode is sensitive to any slight variation on the metal surface. In this project, we will investigate the frequency variation of SPP in time modulated waveguides. The following aspects are concerned: (1) Design SPP waveguide by using which the propagation of SPP can be dramatically influenced by external modulations; (2) Theoretically analyze and numerically simulate SPP propagating in periodic or aperiodic time modulated waveguides; (3) Design active plasmonic devices based on time modulated SPP waveguides. The study in this project will reveal the physical analogy between the frequency evolution in time modulated waveguides and the discrete diffraction in waveguide arrays that are formed by spatial modulation. It also provides a new method to design active plasmonic nanodevices. The SPP based time modulated waveguides will find great applications in next generation active devices such as plasmonic modulators, frequency convertors, and switches which are of ultrahigh speed, low loss and high integration density.