title: Focused optical beams obtained at planar structures by an imaginary shift in position.
abstract: A theory for focused optical beams at planar structures is described. It is an extension of a previous theory based on summation of plane waves. The focused beam is obtained by an imaginary shift in the position vector of the plane waves. It is well suited for calculations of electromagnetic fields at planar surface plasmon resonance structures excited by a focused optical beam.
authors.affiliation: Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden. nils.calander@chalmers.se
authors.forename: Nils
authors.initials: N
authors.lastname: Calander