Multiple plasmon resonance in a concentric silver-atomic medium nanoshell

Abstract

Optical properties of a concentric silver-atomic medium nanoshell are investigated based on the quasi-static and Maxwell-Garnett approximations. We consider the atomic medium as Λ-type three-level atoms driven simultaneously by a coupling field and a probe field. It is shown that the strong coupling between atoms and sphere plasmon of silver core emerges of multiple-mode and ultra narrow-band absorption spectra by controlling the permittivity of the atomic medium. In particular, coherent driving of the coupling field allows us to manipulate surface plasmon resonances, including frequency shift and bandwidth modification. Furthermore, we demonstrate that selective absorption enhancement of different modes can be achieved by tuning the radius of the core and the shell. These absorption properties yield potential applications of the nanoshells as ultracompact tunable nonlinear optical devices.

Negative refractive index enhancement with zero absorption in a concentric chiral metal-atomic nanoshell

“…m  and δ → 1 in equation (14). Here, in the presence of a relatively weak coherent driving field, propagation of the incident wave field through the atomic shell produces an EIT effect similar to the result reported in [51] (not shown). The absorption lines of the EIT spectrum separated by a dark line are displaced far from each other when the coupling strength of the driving field becomes very strong (see the solid and dotted lines in figure 2(b¢)).…”

“…The nanostructure of the concentric metal-atomic nanoshell can be effectively approximated as either a metal sphere or an atomic shell using a methodology akin to the approach employed in [55]. We find that the absorption spectrum exhibits a Lorentzian-like statistical behavior (see figure 2(c)) agreeing with the result shown in [51], however, with additional influence from the chiral coefficients of medium while approximating the concentric metal-atomic nanoshell to metal sphere interacting with the incident field using the parametric values ξ 2 → 0, 1…”

“…In such a situation, the transparency regime within the absorption lines becomes wider [69]. Secondly, employing a similar approximation method, σ M for the chiral metal sphere (atomic shell) produces a Lorentzian-like (a doublet) spectrum agreeing with the finding in [51], however, with the additional influence from the chiral coefficients of the medium (see the dash-dotted (dotted) line in figure 2f(e)). Note that in comparison to the electric absorption, the magnetic absorption spectrum is mild revealing that the coupling of the magnetic field with the respective medium is a weakcompared to its electric counterpartcoupling of the electric field [27].…”

“…It has been observed that previous studies have examined the light scattering efficiency associated with multiple plasmon resonances in core-shell nanoparticles comprising both metal-core and shell configurations within two-level atomic systems [50], as well as within three-level atomic systems [51]. Within these studies, it has been noted that the enhancement in light scattering efficiency can be attributed to the presence of a quantized atomic shell in the hybrid system.…”