Enhancement of and interference among higher order multipole transitions in molecules near a plasmonic nanoantenna

Abstract

Spontaneous emission of quantum emitters can be modified by their optical environment, such as a resonant nanoantenna. This impact is usually evaluated under assumption that each molecular transition is dominated only by one multipolar channel, commonly the electric dipole. In this article, we go beyond the electric dipole approximation and take light-matter coupling through higher-order multipoles into account. We investigate a strong enhancement of the magnetic dipole and electric quadrupole emission channels of a molecule adjacent to a plasmonic nanoantenna. Additionally, we introduce a framework to study interference effects between various transition channels in molecules by rigorous quantum-chemical calculations of their multipolar moments and a consecutive investigation of the transition rate upon coupling to a nanoantenna. We predict interference effects between these transition channels, which allow in principle for a full suppression of radiation by exploiting destructive interference, waiving limitations imposed on the emitter’s coherence time by spontaneous emission.

Multipolar Resonances with Designer Tunability Using VO2 Phase-Change Materials

“…7) that may be used for complex tunable interference phenomena between different multipoles, hence opening a wealth of different possibilities of spatially distributing the scattered light for directionality control purposes (see [42,51] for more details). This tunable multipole can also find interest in the recently proposed framework of spontaneous emission engineering through intereferences between higher-order multipoles [52].…”

“…This implantation process can be carried out in many different CMOS-compatible platforms such as thermal SiO 2 on silicon substrate and results in a flat surface that does not require any complex postprocess step such as CMP to planarize the device. A next logical step is to integrate nanophotonic devices on top of this metamaterial for a wealth of tunable functionalities such as an active control of spontaneous light emission [9,52,57] or dynamically tunable Huygen's metasurfaces [58].…”

Silicon cuboid nanoantenna with simultaneous large Purcell factor for electric dipole, magnetic dipole and electric quadrupole emission

“…ED emission can be enhanced through plasmonic and dielectric nanoantenna 31−33 , while MD emission can be enhanced through split ring resonance 34 , diabolo antenna 35 , dielectric antenna 36−38 , and sandwiched structure 39,40 . Several researchers have shown to enhance both ED and MD emission by silicon nanosphere or plasmonic antenna 41,42 , and others have also shown to enhance ED, MD and EQ emission by the plasmonic sandwiched structure 43 . However, the enhancement factor among the emitters has different magnitudes that are not always satisfactorily large.…”

Direct Excitation of Triplet State of Molecule by Enhanced Magnetic Field of Dielectric Metasurfaces

“…An optical transition between two states is governed by the electron-photon interaction Hamiltonian that can be written using a multipolar expansion of the electric (E) and magnetic fields (B) as, [1,2] Another more versatile approach to enhance the forbidden S 0 →T 1 transition is manipulating not the electron configuration of a molecule, but the electromagnetic environment. [10,17,18] Since spin-flip transition is allowed in the magnetic dipole transition (second term in Equation 1), which is proportional to the intensity of the magnetic field at the transition frequency, the S 0 →T 1 transition is enhanced if a molecule is placed in highly enhanced magnetic field. The effect of optical magnetism on electronic transition of a molecule has been discussed for plasmonic nanoantennas.…”