Signal distortion and scattering losses in on-chip plasmonic communication

Abstract

The enhancement of scattered field from cylindrical structures in the presence of surface plasmon polariton (SPP) waves is analyzed. The SPP waves are excited using the Turbadar-Kretschmann-Raether (TKR) configuration and a cylindrical wave approach (CWA) is implemented to obtain the scattered field. Different arrangements such as a corner reflector and a strip are simulated by means of multiple metallic circular scatterers. It is noted that the back-scattered field from the strip is very strong and can be one of the main challenges in plasmonic communication. Moreover, the simulations give the idea that what combination of structure size and distance from the interface does not produce significant scattering for both the strip and corner reflector. To better understand the phenomenon, and to provide a good insight, two-dimensional near zone field maps are generated to observe field in the vicinity of the object. In the presence of SPP waves, simulations show strong field near the edges like dipole field which is contrary to usual scattering in the absence of SPP waves for a plane wave illumination. In a second problem, scattering of SPP waves excited by a sinusoidal grating from a metallic circular scatterer is described. The extended boundary condition method (EBCM) is utilized to derive the reflectance and transmittance. The angles of exciting SPP (θSPP) are measured by analyzing the behavior of reflectance. Numerical results are reported for different values of the size and distance of scatterer from the grating. It has been observed that the scattered field increases as the size of the scatterer increases. Additionally, the scattered field intensity is much higher when the angle of the incident is equal to the angle of SPP wave excitation (θi = θSPP) than when the angle of the incident is not θSPP. The scattered field reduces as the distance of the scatterer from the grating increases, which shows that the effect of SPP waves near the interface is much stronger than away from the interface. Additionally, the effect of the period and height of the grating on the scattered field are also analyzed. By increasing the period from 900 nm to 1700 nm, the position and the width of the peaks change. It has been noticed that the scattered field increases with an increase in the height of the grating. From the above analysis, it is evident that the signal propagation will be interrupted by the presence of a strong scattered field. Interference of SPP wave propagation with scattered fields is quite obvious. Moreover, the reception of SPP scattering at the receiver is another factor that will distort the information sent to the receiver. The simulated scenarios help in determining the combination of size and distance which does not distort the signal propagation due to scattering effects. This simulation gives an idea of how far an object should be in order to avoid scattering effects in plasmonic communication. It can be deduced that the scattering effect can be neglected for the SPP wave propagation when the distance of the object is h = 100 nm with size R = 5 nm.