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

چکیده مقاله

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 λ = 1310, and 204 nm for λ = 1550 nm. Linear chains of particles can transport the electromagnetic energy at λ = 1310 nm, with transmission losses γ_L = 3 dB/452 and γ_T = 3 dB/446 nm and group velocities v_gL = 0.336C₀ and v_gT = 0.256C₀ for longitudinal and transverse polarizations, respectively, where C₀ is the speed of light in the vacuum. At λ = 1550 nm, γ_L = 3 dB/490, γ_T = 3 dB/604, v_gL = 0.382C₀ and v_gT = 0.260C₀. 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.