Mimicking electromagnetically induced transparency in the magneto-optical activity of magnetoplasmonic nanoresonators

Abstract

We show that the interaction between a plasmonic and a magnetoplasmonic metallic nanodisk leads to the appearance of magnetooptical activity in the purely plasmonic disk induced by the magnetoplasmonic one. Moreover, at specific wavelengths the interaction cancels the net electromagnetic field at the magnetoplasmonic component, strongly reducing the magneto-optical activity of the whole system. The MO activity has a characteristic Fano spectral shape, and the resulting MO inhibition constitutes the magneto-optical counterpart of the electromagnetic induced transparency.

Interaction effects on the magneto-optical response of magnetoplasmonic dimers

“…2 , and due to the low Co concentration, there is no noticeable difference between the three situations. All cases show two characteristic low-energy (740 nm) and high-energy (620 nm) modes of antisymmetric and symmetric nature, respectively [6,13,20], as directly concluded by the obtained relative phase between the two dipoles. The abrupt change in sign of the cosine occurs exactly at the minimum in magnitude of both dipoles.…”

“…By an adequate design of their internal structure, it is possible to obtain configurations which provide enhanced magnetooptical (MO) activity upon plasmon resonance excitation [15][16][17][18], which allow one to probe the electromagnetic (EM) field distribution inside a metallic nanoelement [19], or which yield high MO activity and low optical losses with MO figures of merit comparable with those of garnet structures [13]. Furthermore, in dimers where one of the elements is purely plasmonic and the other is of magnetoplasmonic nature, interaction effects cause the magnetoplasmonic component to induce MO activity in the plasmonic one (which intrinsically lacks MO activity) [20]. For specific interelement distances, which determine the interaction between them, this brings as a consequence the equivalent of the EIT in the MO spectrum of the system, i.e., a cancellation of the MO activity in a narrow spectral range due to the competition between the intrinsic MO contribution of the magnetoplasmonic component and the induced MO contribution of the plasmonic one [20].…”

“…Furthermore, in dimers where one of the elements is purely plasmonic and the other is of magnetoplasmonic nature, interaction effects cause the magnetoplasmonic component to induce MO activity in the plasmonic one (which intrinsically lacks MO activity) [20]. For specific interelement distances, which determine the interaction between them, this brings as a consequence the equivalent of the EIT in the MO spectrum of the system, i.e., a cancellation of the MO activity in a narrow spectral range due to the competition between the intrinsic MO contribution of the magnetoplasmonic component and the induced MO contribution of the plasmonic one [20]. As this effect exhibits a narrow spectral feature in the MO response, it may find applications in sensing and telecommunication areas, and a complete understanding will help in the development of novel sensing and biosensing architectures as well as MO devices.…”

“…We will concentrate on the most interesting case of medium interactions [20], and will analyze two situations: one in which the amount of Co in the magneto-optical disk is very small (0.1%) and a second one where it is comparable to the Au amount (25%). For the analysis, the aspect ratios of the dipoles are a/c = 13 and 10 for the bottom and top dipoles, respectively.…”

“…Beyond the purely optical properties, fully understandable by simply considering p x , the direct consequence of the application of a magnetic field is the generation of a y component in the dipole [20,23] Let us examine each situation individually. When the MP dipole is at the bottom, a y component is observed not only in this dipole, but also in the P top one, which is due to the interaction between the dipoles.…”