Strong Modification of Magnetic Dipole Emission through Diabolo Nanoantennas

Abstract

Magnetic dipole transitions in matter are known to be orders of magnitude weaker than their electric dipole counterparts. Nanophotonic and plasmonic structures have the potential of strongly enhancing the optical magnetic fields in the near field, making these nanostructures ideal candidates to control and enhance the emission of magnetic dipole transitions. Here we theoretically investigate the potential of resonant optical nanoantennas based on diabolo and on metal− insulator−metal diabolo configurations to strongly modify the magnetic dipole of emitters. We find that both configurations provide unprecedented 10 2 -to 10 3 -fold enhancement of the total and the radiative decay rates of a magnetic dipole moment. We show that these two nanoantennas have opposed effects on the quantum yield of the magnetic dipole, translating into different antenna efficiencies. Furthermore, by using a magnetic dipole moment as a theoretical optical nanosensor, we numerically mapped the behavior of the magnetic local density of states (MLDOS) in the entire plane close to the diabolo nanoantenna. We demonstrate the strong confinement and local enhancement of the MLDOS by the nanoantenna. As such, these results underscore the unique ability of optical nanoantennas to control light emission from magnetic dipoles, opening new technological avenues in the magneto-optical domain.

Isotropic Magnetic Purcell Effect

“…[20][21][22][23][24] Magnetic dipole (MD) emission can be enhanced via metallic surface, 2 split-ring resonator, 14 plasmonic nanoburger 25 and diabolo nanoantenna. 26 However, considerable absorption of these metallic structures results in low extrinsic quantum yield in the visible spectrum. A better solution is to employ nano-resonators made from dielectric materials with high permittivity.…”

Magnetic light and forbidden photochemistry: the case of singlet oxygen

“…[37][38][39][40][41][42][43] The strong magnetic field produced by metallic nanostructures can be used to enhance the MD transitions of chemical species placed in their vicinity (see reference 44 for a comprehensive review). Such possibility has been theoretically explored, [45][46][47] and experimentally verified using principally rare-earth ions, which exhibit strong MD in the optical range associated with their 4f orbitals, [48][49][50] placed in closed proximity to plasmonic structures with different designs. [51][52][53][54][55][56][57][58][59] It is important to note that the strong magnetic field enhancement produced by plasmonic nanostructures in their surroundings normally comes together with an even stronger amplification of its electric counterpart, 60 which enhances the ED transitions of the chemical species.…”

Evolutionary Optimization of All‐Dielectric Magnetic Nanoantennas

“…After experimental demonstrations of the coupling between magnetic dipolar emitters and nonresonant photonic structures, both dielectric and plasmonic optical nanoantennas were recently proposed to boost the magnetic field of light in several theoretical studies. Along the same lines, some of these structures were theoretically shown to strongly increase the emission rates of magnetic dipoles . In fact, experimental evidence for the capacity of optical nanoantennas to manipulate the emission of such dipoles at visible or near‐infrared wavelengths has been brought about recently.…”