A plasmonic planar lens operating at terahertz (THz) region based on InSb micro-slit array with varying dielectric slit width is designed and numerically investigated. Dielectric slits provide desired phase retardations of beam manipulating with varying phase propagation constant. Taking advantage of the permittivity thermo-tunable property of InSb, the focal spot of this lens can be actively controlled by altering temperature without needing to change the geometry of the device. Furthermore, the focal spot can move along the vertical direction in the focus area by properly choosing the medium filled in the micro-slits. This ultracompact and focal spot tunable planar plasmonic lens may find potential important applications in the imaging, signal processing, and microprobes for THz system and technologies.

设计并数值研究了基于 InSb 微狭缝阵列的在太赫兹 (THz) 区域工作的等离子体平面透镜，具有不同的介电狭缝宽度。介电狭缝提供所需的光束控制相位延迟，并具有不同的相位传播常数。利用 InSb 的介电常数热可调特性，可以通过改变温度来主动控制该透镜的焦斑，而无需改变器件的几何形状。此外，通过适当地选择填充在微狭缝中的介质，焦点可以沿着焦点区域中的垂直方向移动。这种超紧凑和焦斑可调平面等离子体透镜可能在太赫兹系统和技术的成像、信号处理和微探针中找到潜在的重要应用。