焦散线理论是利用光传播轨迹切线簇构造初始波前的一种方法。基于焦散线理论设计和传输的表面波具有局域场增强、传播轨迹可控等优点,在光学显微、光学传感、调控光波耦合等方面具有重要的应用。提出了一种基于焦散线理论的布洛赫表面波激发光栅结构设计方法。利用双线性光栅结构进行数值模拟实现了可传播100 μm的类无衍射表面波,并分析了光栅结构参数对表面波耦合效率的影响。进一步,根据焦散线理论设计了一种简单的光栅结构,经模拟计算,该光栅结构能够实现沿任意轨迹自加速传输表面波的激发调控。研究结果为操纵亚波长尺度下光波的传输和片上光互联的端口设计提供了一种有效途径。

Caustic theory is a method of constructing the initial wavefront by using the tangent clusters of the light propagation trajectories. The surface wave designed and transmitted based on the caustic theory has the advantages of local field enhancement and controllable propagation trajectory, so it has important applications in optical microscopy, optical sensing, and control of light wave coupling. A method for designing the grating structure of Bloch surface wave excitation based on the caustic theory is proposed. Using bilinear grating structure for numerical simulation,a non-diffraction surface wave that can propagate 100 μm is realized, and the influence of the grating structure parameters on the coupling efficiency of the surface wave is analyzed. Furthermore, a simple grating structure is designed according to the caustic theory, which can realize the regulation of self-accelerating transmission of surface waves along any trajectory through simulation calculations. The results provide an effective way to manipulate the transmission of light waves at the sub-wavelength scale and the port design of on-chip optical interconnection.