Far-field superlens for optical imaging beyond diffraction limit and other nano-plasmonic devices

The resolution of far-field optical lenses is fundamentally limited by diffraction which typically is about half wavelength. To overcome this resolution limit and boost the optical microscope applications in nanoscale, I proposed a new optical imaging principle using a so called far-field superlens (FSL) which comprises a slab of silver superlens and a subwavelength grating. By placing the FSL in the vicinity of the object, the evanescent waves from the object can be greatly enhanced by excitation of surface plasmons (SPs) in the silver slab and then converted into propagating waves by the grating. Based on the well designed optical transfer function (OTF) of the FSL, the evanescent waves are able to be retrieved from the propagating waves detection in the far-field. The required OTF and how to realize it in practice was discussed in detail. The final image with subwavelength resolution was reconstructed with the help of a numerical procedure. The designed OTF of the FSL which is the foundation of the FSL has been experimentally proved. Preliminary reconstruction results has revealed that the current designed silver structured FSL has the ability to image feature size down to 50nm using 377nm illumination light. This study opens up a new opportunity for subwavelength real time optical imaging and may lead to many exciting applications in nano-optics, electronics manufacturing and biological imaging.; Several of other nano-plasmonic devices have also been investigated. SP interference was applied to nanolithography. Utilizing exactly the same conditions as conventional photolithography (i-line), high resolution lithography results (∼60nm feature) with various patterns have been demonstrated by both numerical simulation and experiments. A plasmonic lens which comprises circular slit/slits in a metallic film has also been extensively studied. The detailed lens concept, lens properties and performance, and potential applications were presented.