Invited Paper
Controlling the Phase in Plasmonic Systems for Applications in Color Routing and Coherent Perfect Absorption

Chen Yan Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland Shourya Duta-Gupta Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland Kuang-Yu Yang Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland Olivier J.F. Martin Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland

Following Huygens’principle, the signal we perceive from a plasmonic system is determined by the phases of the different nanostructures that compose the system. This phase controls the spatial radiation distribution as well as the spectral response of the system. Indeed, even the field scattered by a simple plasmonic particle exhibits a phase shift of π when the exciting frequency goes through the plasmon resonance. In this presentation, we will show that it is possible to significantly expand the range of phase shifts using more complex nanostructures, especially those that support Fano resonances. By composing a metasurface with such complex nanostructures fabricated in silver, we are able to control the scattered light and channel different colors into different directions. In a second series of experiments, we will show that by controlling the phase of two beams incident on the plasmonic system, we can tune the absorption in the system from 18% to 96%, reaching nearly coherent perfect absorption. The resulting dramatically increased near-field will be probed by studying the SERS signal of molecules in the plasmonic near-field.

olivier.martin@epfl.ch









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