Far-field superfocusing with optical fiber based surface plasmonic lens made of nanoscale concentric annular slits
Yuxiang Liu, Hua Xu, Felix Stief, Nikolai B. Zhitenev, Miao Yu
We present experimental demonstration of three-dimensional superfocusing by using an optical fiber based surface plasmonic (SP) lens with nanoscale concentric annular slits. To the best of our knowledge, this is the first time that a far-field, sub-diffraction-limit sized focus is achieved with an optical fiber based device. The performance of the SP lens with three slits was experimentally characterized. Guidelines and suggestions on designing the SP lens were provided. As a microscale device with nanoscale features, the fiber-based SP lens can provide a solution to bridge nanophotonics and conventional optics.