Exploiting the interaction between a semiconductor nanosphere and a thin metal film for nanoscale plasmonic devices

Abstract

The interaction of silicon (Si) nanospheres (NSs) with a thin metal film is investigated numerically and experimentally by characterizing their forward scattering properties. A sharp resonant mode and a zero-scattering dip are found to be introduced in the forward scattering spectrum of a Si NS by putting it on a 50-nm-thick gold film. It is revealed that the sharp resonant mode arises from a new magnetic dipole induced by the electric dipole and its mirror image while the zero-scattering dip originates from the destructive interference between the new magnetic dipole and the original one together with its mirror image. A significant enhancement in both electric and magnetic fields is achieved at the contact point between the Si NS and the metal film. More interestingly, the use of a thin silver film can lead to vivid scattering light with different color indices. It is demonstrated that a small change in the surrounding environment of Si NSs results in the broadening of the resonant mode and the disappearance of the zero-scattering dip. Our findings indicate that dielectric-metal hybrid systems composed of semiconductor NSs and thin metal films act as attractive platforms on which novel nanoscale plasmonic devices can be realized.

Tailoring the spatial localization of bound state in the continuum in plasmonic-dielectric hybrid system

“…It is noticed that the MD moment contributes negatively to the total extinction in the presence of the Ag film, because of bianisotropic effect implying a destructive interference between the fields scattered by the ED and MD moments [36]. More importantly, such bianisotropic effect also results in the shrinkage of the ED resonance's line width [14], as clearly shown in Figure 1C.…”

“…Similarly, the hybrid concept was used to boost the Purcell factor and generate efficient hot electron luminescence from a silicon (Si) nanowire coated with a thin Ag film [12]. Furthermore, such a strategy can be generalized to the three-dimensional case for realizing strong localization of optical field in particleon-film systems where dielectric nanoparticles (such as Si nanospheres) supporting distinct Mie resonances were used [13,14]. As an exemplary application, the significantly enhanced electric field mediated by the mirrorimage-induced magnetic dipole mode was exploited to enhance Raman scattering and photoluminescence [15].…”

Metal Substrate-Induced Line Width Compression in the Magnetic Dipole Resonance of a Silicon Nanosphere Illuminated by a Focused Azimuthally Polarized Beam

“…As some examples, we will show in the following numerical simulation the possible applications of the sharp MD resonance in nanoscale sensing and color display. For practical applications, the metal substrate is chosen to be a 50- nm-thick Au film, which has been used in our previous study [28]. The physical mechanism for the line width compression of the magnetic dipole resonance is the coherent interaction of the magnetic dipole and its mirror image induced by the metal substrate.…”

“…Previously, it has been demonstrated that intensity shift sensors based on Si NS dimers possess much higher sensitivity than wavelength shift sensors based on plasmonic nanoparticles/nanostructures [51]. In addition, the sensitivity of the Si NS placed on a metal substrate and excited by linearly polarized light was also experimentally studied in our previous work [28]. In our case, the scattering spectrum dominated by a sharp MD resonance with a narrow line width is quite suitable for sensing applications, as demonstrated in the following.…”

Manipulating the Orientations of the Electric and Magnetic Dipoles Induced in Silicon Nanoparticles for Multicolor Display

“…In principle, the scattering properties of the Si NS can be modified by varying either the surrounding environment or the illumination configuration . It has been shown that both the forward and backward scattering spectra of a Si NS can be changed by using a metal film . Moreover, it has been demonstrated that optical pulling force acting on a nanoparticle can be generated by using a single Bessel beam or two interfering plane waves which modify the forward and backward scattering properties of the nanoparticle .…”