Design, fabrication and test of a cascaded plamonic superlens

在传统显微镜下直接观察的超分辨率成像对于生物和纳米技术是非常期望的，因为它能够对纳米尺寸的物体进行非破坏性成像和监测。为了实现可见光波段的远场实时超分辨成像，本项目研究了一种由两个等离子体单元组成的级联超透镜系统。一种是双层曲折腔（DLMC）结构，用于支持具有大空间频率的波的传播。另一个是平面等离子体透镜（PPL），用于将来自DLMC结构的波放大耦合到自由空间。在本计画的第一阶段中，我们数值研究并制作了级联电浆超透镜系统。我们的模拟证明了预期的亚波长成像能力与放大的成像系统在640 nm波长。两个单独的等离子体元件也被成功地制作，与其结构参数的精确控制证明。然而，目前的设计仍然存在一些局限性。在项目的第二阶段，我们将通过结构修改和优化来解决这些问题。我们将进一步优化系统的几何参数，以减少DLMC和PPL之间的耦合距离，这将有助于在纳米加工中集成这两个元件。我们还将优化DLMC结构的纳米制造工艺，以增加其光传输。通过改变DLMC结构的中心区域，解决了现有级联成像系统中目标与曲折槽的对准问题。最后，利用我们的空间影像扫描显微镜，制作出经过优化设计的超透镜成像系统，并对超透镜后的场分布进行表征

Super-resolution imaging with direct observation under conventional microscopes is highly desirable for biological and nano-technologies since it is capable of non-destructive imaging and monitoring for nano-sized objects. To achieve far field real-time super-resolution imaging at visible wavelength we study a cascaded plasmonic superlens system in this project, which is composed of two plasmonic elements. One is a double layer meander cavity (DLMC) structure used to support the propagation of waves with large spatial frequencies. The other one is a planar plasmonic lens (PPL) used to couple the waves from the DLMC structure to free space with magnification. In the first phase of this project we have numerically studied and fabricated the cascaded plasmonic superlens system. Our simulation demonstrated the expected subwavelength imaging capability with magnification of the imaging system at 640 nm wavelength. The two individual plasmonic elements were also fabricated successfully, with which precise control of structural parameters was demonstrated. However, there are still some limitations with the current design. In the second phase of the project we will solve these problems through structure modification and optimization. We will further optimize geometrical parameters of the system in order to reduce the coupling distance between the DLMC and the PPL, which will facilitate the integration of the two elements in nano-fabrication. We will also optimize the nano-fabrication process of the DLMC structure to increase its optical transmission. Through modifying the center area of the DLMC structure, we will solve the alignment problem between the object and the meander grooves with the current cascaded imaging system. Finally, the optimized imaging system with modified design will be fabricated and field distributions behind the fabricated superlens will be characterized by using our aerial image scanning microscope