Numerical study of dumbbell-shaped gold nanoparticles using in plasmonic waveguides in near infra-red spectrums

In this paper, we investigated plasmonic waveguides in near infra-red spectrum using dumbbell-shaped gold nanoparticles. It is possible to shift localized surface plasmon resonance (LSPR) to the desired wavelength with proper geometrical properties. 3-D FDTD simulations are used to determine the set of geometrical parameters of nanoparticles to obtain LSPR at 1310 and 1550 nm. Employing different configuration of nanoparticles chains, we not only can design waveguides with better optical characteristics but also achieve the demultiplexing function in V-form arrays. The proposed nanoparticles show sharp resonance peak, 168 FWHM bandwidth for lambda = 1310, and 204 nm for lambda = 1550 nm. Linear chains of particles can transport the electromagnetic energy at lambda = 1310 nm, with transmission losses gamma(L) = 3 dB/452 and gamma(T) = 3 dB/446 nm and group velocities v(gL) = 0.336C(0) and v(gT) = 0.256C(0) for longitudinal and transverse polarizations, respectively, where C-0 is the speed of light in the vacuum. At lambda = 1550 nm, gamma(L) = 3 dB/490, gamma(T) = 3 dB/604, v(gL) = 0.382C(0) and v(gT) = 0.260C(0). Moreover, we attained 8.13 as minimum ratio of averaged electric field intensity and 36.8 as minimum ratio of averaged Poynting vector as a function of position between two ports in demultiplexing function.