Plasmonic Nanostructured Cellular Automata

Introduction:A one-dimensional cellular automaton (CA) consists of a sequence of consecutive cells where each cell can take a value between 0 and k-1 which then is updated in generation-by-generation. CA's can be found in... [ view full abstract ]

Introduction:

A one-dimensional cellular automaton (CA) consists of a sequence of consecutive cells where each cell can take a value between 0 and k-1 which then is updated in generation-by-generation. CA's can be found in universal dynamic models that govern several naturally existing phenomena from DNA sequences to galactic formations. We believe that employing these nature-complying rules as models in different artificial systems and structures, such as sensing, imaging, and energy harvesting applications, can introduce positive enhancements to their capabilities, efficiency, and energy utilization. We investigated the scattering plasmonic resonance profiles of silver spherical nano-particles when CA33 is used as a model of their configurations where 1's and 0's indicate either their presence or absence.

Methods:

The analysis model is based on the numerical time-domain solution of Maxwell's equations. The scattering of light waves off the nanoshperes is simulated by implementing the Finite-Difference-in-Time-Domain method in a 3D Yee's staggerd mesh. Moreover, the plasmonic resonance modes are obtained through the Total-Field-Scattered-Field method. Finally, the dispersive nature of the silver nanospheres was simulated following the Lorentz–Drude model.

Results & Discussion:

CA33 is an elementary one-dimensional CA rule whose cells can occupy one of two states. This rule is used in RNG's and models few natural phenomena.
Firstly, a single nanosphere was put at the top middle the total region whose scattering profile matched that of a typical silver nanoshpere, i.e. 2 modes. The Figure shows a side and a top view of the configuration resonance after eight generations. For the first 3 generations, the scattering profile only witnessed red-shift in both peaks as shown in the Figure by the dotted curve.
However, after introducing the fourth generation, peculiarly, two new peaks emerge as shown in the Figure by the solid curve. Moreover, the newly added nanospheres in the fourth generation were isolated and their scattering profile was found and is represented in the Figure by the dashed curve.
It is clear that the scattering profile after four generations is not merely a superposition of the preceding generations and the newly added particles, but rather, it introduces its unique profile that keeps evolving with generations.