Abstract
Active, ultra-fast external control of the emission properties at the nanoscale is of great interest for chip-scale, tunable and efficient nanophotonics. Here we investigated the emission control of dipolar emitters coupled to a nanostructure made of an Au nanoantenna, and a thin vanadium dioxide (VO2) layer that changes from semiconductor to metallic state. If the emitters are sandwiched between the nanoantenna and the VO2 layer, the enhancement and/or suppression of the nanostructure's magnetic dipole resonance enabled by the phase change behavior of the VO2 layer can provide a high contrast ratio of the emission efficiency. We show that a single nanoantenna can provide high magnetic field in the emission layer when VO2 is metallic, leading to high emission of the magnetic dipoles; this emission is then lowered when VO2 switches back to semiconductor. We finally optimized the contrast ratio by considering different orientation, distribution and nature of the dipoles, as well as the influence of a periodic Au nanoantenna pattern. As an example of a possible application, the design is optimized for the active control of an Er3+ doped SiO2 emission layer. The combination of the emission efficiency increase due to the plasmonic nanoantenna resonances and the ultra-fast contrast control due to the phase-changing medium can have important applications in tunable efficient light sources and their nanoscale integration.
Highlights
One of the main goals of modern nanophotonics is the use of optical nanocomponents as building blocks of integrated circuits for applications in future computers and information systems
In the present work we demonstrated that the combination of a phase-change material and a plasmonic nanostructure can be effectively used to externally modulate the emission of magnetic dipoles
We have shown that a hybrid nanostructure consisting of magnetic dipoles sandwiched between an Au nanoantenna array and a multilayer structure containing VO2 can lead to efficient modulation of the Er3+ emission at 1540 nm
Summary
One of the main goals of modern nanophotonics is the use of optical nanocomponents as building blocks of integrated circuits for applications in future computers and information systems. Erbium-based materials are preferred to semiconductors in quantum information systems due to their emission at telecommunication wavelengths with sharp spectral features. The emission efficiency can be enhanced by putting the emitters in the near-field of nanostructures designed to have resonances that match the wavelength of excitation or emission [4,5,6,7,8,9] Another issue is to combine efficiency and modulation speed by dynamical manipulation of the local density of states. We combined the enhancement of a dipolar emitter emission due to the proximity of a resonant nanostructure, and the possibility to modulate it by means of a thin layer of a phase change material (PCM). This study is of particular importance due to the mixed nature of Er3+ transition at 1540 nm, where both electric and magnetic dipole components are of the same order of magnitude [23,24,25]: a resonant magnetic field can be used to enhance the corresponding transition, and switch it by means of PCM
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