Date and Time Thursday, Nov. 6, 2014, 3:00 PM - 4:00 PM
Location SF B560
Host Hans-Dieter Lang

Optical Huygens' Metasurfaces with Independent Control of the Magnitude and Phase of the Local Reflection Coefficients

Minseok Kim

Electromagnetics Group (Prof. Eleftheriades), University of Toronto


Funny mirrors at the amusement park entertain us by showing shortened, stretched, or any exotic images of ourselves which we only have imagined before. We see distorted images from such mirrors because they are curved in such a way that the direction of the light scattered off from the mirror is different from the usual flat mirrors. What if we can create some flat surfaces that offer arbitrary control of the scattered light? These flat mirrors would not only entertain us, but they can have a huge implication in the field of nano-photonics where a thin and flat device is required to arbitrarily tailor the scattered light. To arbitrarily control the scattered light, one would need a surface where each point on the surface can independently tune the magnitude and phase of the reflected light. In fact, recent advances in nano-fabrication techniques have allowed us to build artificial surfaces known as metasurfaces to get closer to such goal. These surfaces contain sub-wavelength sized "meta-atoms" where their electrical response alone has been emphasized in recent metasurface research. As a result, there has not been any practical metasurface that can completely control the scattered light.

In this talk, we show how one can utilize both the electric and magnetic responses of the meta-atoms to independently tune the magnitude and phase of the local complex reflection coefficients. The meta-atom consists of a pair of nanorods made of gold separated by a thin silica layer. We show that such a structure is capable of simultaneously supporting both electric and magnetic resonances and their directions are orthogonal to each other. Such configuration is known as a Huygens' source and by employing its equivalent circuit model, we show the design of an example surface which can asymmetrically split the incident light to any direction.


Minseok Kim received his B.A.Sc and M.A.Sc from the University of Toronto in 2011 and 2013 respectively. He is currently a Ph.D. candidate at the University of Toronto in the Electromagnetics group under the supervision of Professor George V. Eleftheriades.