title: Theory and implementation of focal shift of plasmonic lenses.
abstract: We utilize three diffraction theories to investigate the focal-shift phenomena of plasmonic lenses. By taking the Fresnel number into account, a better accuracy in predicting the relative focal shift can be achieved for low-Fresnel-number systems. On the basis of this focal-shift effect, we present a method to realize an active plasmonic lens. Two-dimensional finite-difference time-domain simulation is performed to verify the method proposed.
authors.affiliation: Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg, Germany. yiting.yu@imtek.uni‐freiburg.de
authors.forename: Yiting
authors.initials: Y
authors.lastname: Yu
authors.forename: Hans
authors.initials: H
authors.lastname: Zappe