Design, fabrication and test of a cascaded plamonic superlens

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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