Creation and Annihilation of Optical Phase Singularities

Using a rigorous scattering model we study the electromagnetic field around a subwave-length slit in a metal plate with finite conductivity and finite thickness. It is found that the transmission can be strongly enhanced when the phase singularities (“optical vortices”) of the Poynting vector field have a certain position. We examine the creation and anni-hilation of different kinds of phase singularities as a function of the incident wavelength and slit width. The analysis of light transmission through a slit with a sub-wavelength width in a thin plate is a subject with a venerable history [1, 2, 3], dating back to Lord Rayleigh. Be-cause of its importance for near-field optics and semiconductor technology, it continues to attract attention. Recently Ebbesen et al. observed extraordinary light transmission (i.e., more than 100%) through an array of sub-wavelength holes [4], which led to a new wave of interest in the subject. In this paper we study the light transmission through a single sub-wavelength slit in a metal plate of finite conductivity for the TE-polarization case. A rigorous computation of the field [5] demonstrates that for certain widths, there is an enhanced transmission through the slit. To understand this anomalous transmission