Spatially Structured Optical Effects in a Four‐Level Quantum System Near a Plasmonic Nanostructure
Hamid Reza Hamedi, Vassilios Yannopapas, Emmanuel Paspalakis
Abstract
Abstract The light–matter interaction for a four‐level double‐V‐type quantum system interacting with a pair of weak probe fields while located near a 2D array of metal‐coated dielectric nanospheres is studied. A situation is considered in which one of the probe field carries an optical vortex, that is, an electromagnetic field with optical angular momentum, and the other probe field has no vortex. It is demonstrated that due to the phase sensitivity of the closed‐loop double V‐type quantum system, the linear and nonlinear susceptibility of the non‐vortex probe beam depends on the azimuthal angle and orbital angular momentum (OAM) of the vortex probe beam. This feature is missing in an open four‐level double V‐type quantum system interacting with free‐space vacuum, as no quantum interference occurs in this case. The azimuthal dependence of optical susceptibility of the quantum system is used to determine the regions of spatially structured transparency.