Spoof Plasmons / Designer Surface Plasmons

Posted on Thu 07 October 2010 in Plasmonics

Aim of this article/post: To 1) introduce the concept of Designer surface plasmons or Spoof plasmons and 2) Dispersion relations and Visualization of the fields using MEEP code. (Some of the text/simulations are taken from my paper in the area of DSPs.)

Surface Plasmons are electromagnetic waves that travel at the interface of metals such as Ag/Au (follow Lorentz-Drude dielectric model) and a dielectric. Surface plasmons are not expected in perfect electric conductors (PEC's) as the electric field inside the metal is zero. However, highly localized surface-bound states appear when the PEC is periodically modulated with arrays of sub-wavelength square or circular holes. Both theoretical and experimental studies suggest that surface-bound states and SPs exhibit similar dispersion relationships. Due to the similarity such surface-bound states are referred to as ‘spoof’ or ‘designer’ surface plasmons (DSPs).

Structured PEC surfaces and the excited DSPs have recently garnered interest within the photonics community, as a new platform to engineer surface-bound states of a wide frequency range.  An important example is the guiding of terahertz-range radiation  in the form of DSPs. This enables the application of terahertz plasmonics to near-field imaging, sensing, and spectroscopy. A prime advantage of DSP is that, unlike conventional SP, the propagation of these waves can be controlled by engineering the material-independent, perceived group index. PEC structures have been engineered to guide DSPs of speci?c terahertz-range frequencies. To know more about DSP's and relevant references, see references in my paper on DSP's here.

In the figure below, I show how DSP's are excited. I also show numerically calculated dispersion curves and fields. These were obtained using freely available finite difference time domain simulation software, MEEP.

[caption id="attachment_624" align="aligncenter" width="502"] Schematic shows the excitation of Designer surface plasmons (DSPS) (left). Inset shows the fields (Ey and Ex). Dispersion relationship of these waves (right))[/caption]

[Update on May 2 2013:]{style="color: #ff0000;"} (Here is my project file)