Polarization Dependent Enhancement of Magnetic Dipolar Emission with Silicon Nanodimers

TL;DR

The problem addressed is controlling Eu3+ emission from two dipolar transitions using nanophotonic structures. The approach uses a hybrid silicon nanodimer with a gap-confined Eu(TTA)3 emitter, optimized by finite element simulations (COMSOL) and fabricated by a two-step EBL process. The key contributions are the demonstration of polarization-dependent enhancement for the magnetic dipole at $590$ nm and electric dipole at $610$ nm, enabling polarization routing through engineered magnetic and electric hotspots. This work highlights magnetic light-matter interactions as a practical degree of freedom for nanoscale emission control with potential applications in integrated photonic devices.

Abstract

Eu(TTA)3 complexes are used as an emission source in the presence of high refractive index dielectric nanostructures. These nanostructures support Mie-type resonances that modify the local density of optical states. Specifically, the silicon dimer provides polarization-dependent electric and magnetic field enhancement in the dimer gap to modify the electric dipolar and magnetic dipolar emissions of the Eu3+ at 610 nm and 590 nm, respectively. Finite element method simulations are used to determine the optimal parameters for the sample and to demonstrate the polarization-dependent emission enhancement of dipolar emitters in the gap. A two-step electron beam lithography process is used to fabricate the hybrid nanoscopic structures, with a Eu3+ doped electron beam resist located only in the center of the dimer. The results demonstrate the potential of these nanostructures to selectively tailor the emission of the two distinct dipolar transitions by engineering the resonant nanostructures. Our work highlights the potential of magnetic light-matter interactions as a novel degree of freedom.

Figures (2)

• Figure 1: a) Near-field maps of silicon dimers with optimal geometry for magnetic field intensity enhancement at $\lambda = 590 nm$, where the incident radiation is linearly polarized with the electric (right figure) or magnetic (left figure) field across the gap. b) Near-field maps of the silicon dimer for the electric field intensity enhancement at $\lambda = 610 nm$, where the incident radiation is linearly polarized with the electric (right figure) or magnetic (left figure) field across the gap.
• Figure 2: a) Schematic overview of the fabrication steps used to create the hybrid nanoscopic. b) scanning electron microscope image of the fabricated dimer $\alpha$Si$:$H with the ma-N$:$Eu(TTA)3 resist in the center.