A far-field super-focusing lens for biological applications

The diffraction limit of light restricts the minimum focal spot size achievable using a dielectric lens to half the wavelength of the light in a medium. Here we present a far-field lens system to achieve super-focusing and super-resolution imaging beyond the diffraction limit. In this system, cylindrical surface plasmons (CSPs), at the wavelength shorter than that of incident light, are excited in a sub-wavelength metallic structure, and a subdiffraction-limited focus of the incident light is formed far-field with the CSPs’ modulation by a dielectric grating. Constructive interference of CSPs gives rise to high focusing efficiency of the lens system. This project aims to apply such far-field nanofocusing lens for biological applications, including super-resolution imaging, nano-particles trapping and manipulation.