Spatial coherence from Nd³⁺ quantum emitters mediated by a plasmonic chain

Abstract

Controlling the coherence properties of rare earth emitters in solid-state platforms in the absence of an optical cavity is highly desirable for quantum light-matter interfaces and photonic networks. Here, we demonstrate the possibility of generating directional and spatially coherent light from Nd3+ ions coupled to the longitudinal plasmonic mode of a chain of interacting Ag nanoparticles. The effect of the plasmonic chain on the Nd3+ emission is analyzed by Fourier microscopy. The results reveal the presence of an interference pattern in which the Nd3+ emission is enhanced at specific directions, as a distinctive signature of spatial coherence. Numerical simulations corroborate the need of near-field coherent coupling of the emitting ions with the plasmonic chain mode. The work provides fundamental insights for controlling the coherence properties of quantum emitters at room temperature and opens new avenues towards rare earth based nanoscale hybrid devices for quantum information or optical communication in nanocircuits.

Silver Nanoparticle Chains for Ultra-Long-Range Plasmonic Waveguides for Nd3+ Fluorescence

“…In this sense, the observation of long-distance emission suggests an effective amplification or compensation effect of the gain material over the plasmonic mode. According to our previous results [ 45 ], the emission from these ions excites the plasmon mode that propagates along the chain, which, in turn, induces their oscillation in phase with the chain. Therefore, the continuous exchange of electromagnetic energy between the ions and the chain partially compensates for the optical losses.…”

“…In particular, the association of plasmonic nanostructures with RE-doped crystals has been revealed as an interesting approach, enabling solid-state platforms with emergent functionalities at subwavelength scales. For instance, dual-wavelength laser operation assisted by plasmonic structures in RE-doped crystals and plasmon-induced spatial coherence in RE emitters have been recently demonstrated [ 44 , 45 ]. Herein, the association of plasmonic arrangements with RE ions is further exploited to demonstrate the possibility of guiding the fluorescence of Nd 3+ ions at ultra-long distances in the subwavelength regime by means of plasmonic chains of Ag NPs.…”

“…In this regard, we have previously shown the presence of the near-field coherent coupling of the Nd 3+ emitting ions with the plasmonic chain mode, which results in the in-phase de-excitation of the emitters with the plasmonic chain [ 45 ]. On the other hand, due to the effective light confinement, the enhancement and coupling of the initial local excitation is also followed by its passive propagation along the chain, which supplies the excitation of the ions in the vicinity of the chain.…”

Enhancement of Light Absorption by Leaky Modes in a Random Plasmonic Metasurface

“…Finding ways to enhance the optical absorption in nanostructures and ultrathin layers is crucial in many modern optoelectronic devices. − Although photovoltaics and photodetection often appear among the most celebrated applications, these days many other scientific areas benefit from subwavelength-scale manipulation of light. Chemical reaction paths can be engineered by confining and absorbing light within resonant nanocavities, novel medical techniques based on nanoscale energy localization like photothermal therapeutics and imaging are emerging, − long-range energy transfer between donor and acceptor molecules can be achieved by nanoscale guiding of energy as well as extended spatial coherence from an ensemble of quantum emitters, and resonant scattering of light is involved in light amplification, lasing, , and Bose–Einstein condensation at the nanoscale …”