Analysis of mutual couplings in a concentric circular ring plasmonic optical antenna array

Abstract

In this paper, we report the analysis of a concentric circular ring plasmonic optical antenna (POA) array using a simple lumped coupled circuit (LCC) model. The currents in the circular rings of the POA array and their mutual couplings are analyzed using the LCC model. The results agree well with the numerical simulation using CST’s Microwave Studio®. The LCC model reveals the mutual couplings between the antenna rings. It is found that the mutual couplings are not only between the adjacent antenna rings, but also involve their second (2nd) nearest or farther neighbors. Since the near-fields of the optical antennas are related to the currents in the optical antennas, the LCC model provides a useful tool for the analysis of the near-field and their mutual interactions in the circular ring POA array.

Surface current confinement in circular ring optical antennas and its enhancement effect to the photoresponse of longwave infrared photodetectors

“…nanometers), the plasmonic resonant condition deviates from the wellknown resonant conditions for semi-infinite metal/dielectric interfaces [2]. The SPR excited surface current in a circular ring antenna can be modeled using an RLC circuit model [43]. Detailed R, L, C calculation can be found in [43].…”

“…The SPR excited surface current in a circular ring antenna can be modeled using an RLC circuit model [43]. Detailed R, L, C calculation can be found in [43]. Since the voltage V in the RLC circuit model is proportional to the E-field in the antenna, one can compare the V spectral profile with that of simulated |E| after normalizing the V and the |E| with their corresponding maximum values.…”

“…The resonant frequency of an RLC circuit is ω 0 = 1/ √ LC . Since both L and C are propotional to the diamater of the antenna ring [43], the resonant frequency ω 0 should be proportional to 1/d 2 . Figure 5 shows the f 0 versus 1/d 2 plots, where f 0 = ω 0 /2π.…”

“…Circular ring optical antennas have shown great promises in light confinement and concentration [37][38][39] and E-field enhancement in the near-infrared (NIR) spectral region [40][41][42]. LSPR modes and the plasmonic resonant wavelengths, their dependence on the ring parameters, as well as the mutual coupling effect and its circuit model, have been reported [37,40,43]. However, the antenna ring width-dependent E-fields and surface current confinement and their effects on photodetector enhancement have not been fully explored.…”

Pattern synthesis of linear and ring arrays with minimum number of elements using FFT and Bessel transformation

“…Antenna arrays have advantages such as fast scan speed in all directions of space, high gain, and no mechanical components. Phased arrays use the amplitude and relative phase difference between the signals fed into properly spaced antennas to obtain the desired radiation pattern 4 , 5 .…”