title: Sub-diffraction phase-contrast imaging of transparent nano-objects by plasmonic lens structure.
abstract: We propose a specially designed plasmonic lens structure to succeed in realizing sub-diffraction phase-contrast imaging of transparent nano-objects. The nano-objects are embedded inside the insulator layer of the metal-insulator-metal (MIM) plasmonic structure and have a small refractive index difference with respect to the transparent insulator layer. The excited surface plasmons in the MIM structure help to greatly enhance scattered light from the nano-objects and effectively suppress the transmitted illumination light. A spatial resolution of about 64 nm and a minimum distinguishable refractive index difference down to 0.05 are numerically demonstrated. For sub-diffraction phase-contrast imaging of irregular three-dimensional (3D) nanowires and nanocylinders, the optimized MIM structure shows much better performance in comparison with that of a superlens.
authors.affiliation: State Key Laboratory of Optical Technologies on Nano-Fabrication and Micro-Engineering, Institute of Optics and Electronics, Chinese Academy of Science, PO Box 350, Chengdu 610209, People's Republic of China.
authors.forename: Na
authors.initials: N
authors.lastname: Yao
authors.forename: Changtao
authors.initials: C
authors.lastname: Wang
authors.forename: Xing
authors.initials: X
authors.lastname: Tao
authors.forename: Yanqin
authors.initials: Y
authors.lastname: Wang
authors.forename: Zeyu
authors.initials: Z
authors.lastname: Zhao
authors.forename: Xiangang
authors.initials: X
authors.lastname: Luo
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D007909:Lenses; D008422:Materials Testing / Q000295:instrumentation*; D053758:Nanoparticles / Q000648:ultrastructure*; D012031:Refractometry / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*