Atomic monolayers of transition metal dichalcogenides represent an emerging material platform for the implementation of ultra compact quantum light emitters via strain engineering. In this framework, we discuss experimental results on creation of strain induced single photon sources using a WSe 2 monolayer on a silver substrate, coated with a very thin dielectric layer. We identify quantum emitters which are formed at various locations in the sample. The emission is highly linearly polarized, stable in linewidth and decay times down to 100 ps are observed. We provide numerical calculations of our monolayer-metal device platform to assess the strength of the radiative decay 1 rate enhancement by the presence of the plasmonic structure. We believe, that our results represent a crucial step towards the ultra-compact integration of high performance single photon sources in nanoplasmonic devices and circuits.Single photon sources are considered as a key building block for quantum networks, quantum communications and optical quantum information processing. 15 To fully harness the properties of such non-classical light sources, core requirements include their long-term stability, 6,7 brightness 811 and scalability in the fabrication process. Recently, quantum light emission from inorganic two dimensional layers of transition metal dichalcogenides (TMDC) 1216 has been demonstrated. While the nanoscopic origin of tight exciton localization is still to be explored, engineering the morphology of carrier substrates and thus the strain eld in the monolayers 17 has enabled position control over such quantum emitters. 1820 One outstanding problem, which we address in this report, is the emission enhancement of such quantum emitters in atomic monolayers. The layered nature of the materials and their intrinsic robustness with regard to open surfaces (due to absence of dangling bonds) naturally puts plasmonic approaches in the focus of interest. A single dipole emitter close to a plasmonic nanoparticle, which act as an optical antenna, 21,22 experience a modied photonic mode density, leading to enhanced radiative decay rates and thus a spontaneous emission enhancement. The enhanced intensity results from an amplied electric eld intensity due to localized surface plasmon resonance of metal nanoparticles. 18,23,24 Plasmonic tuning of the optical properties of molecules, such as dyes close to a metal surface is a topic which is subject to investigations since the 1980s. Pronounced coupling phenomena of dye molecules with surface plasmon resonances in ultra-thin silver lms has been shown via luminescence and absorption studies, 25 as well as resonant transmission. 26 Enhanced uorescence of molecules coupled to Ag-islands has been studied in, 27 whereas uorescence quenching of dye molecules or colloidal CdSe quantum dots in the closest vicinity of metallic surfaces has also been identied to act signicantly on the emitters' decay dynamics. 28,29 Hence it is important to separate the emitters from the metallic layers via a non-conduct...
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We discuss coupling of site-selectively induced quantum emitters in exfoliated monolayers of WSe 2 to plasmonic nanostructures. Squared and rectangular gold nanopillars, which are arranged in pitches of 4 µm on the surface, have sizes of tens of nanometers, and act as seeds for the formation of quantum emitters in the atomically thin materials.We observe chraracteristic narrow-band emission signals from the monolayers, which correspond well with the positions of the metallic nanopillars with and without thin 1 arXiv:1806.06363v1 [cond-mat.mes-hall] 17 Jun 2018 dielectric coating. Single photon emission from the emitters is confirmed by autocorrelation measurements, yielding g 2 (τ = 0) values as low as 0.17. Moreover, we observe a strong co-polarization of our single photon emitters with the frequency matched plasmonic resonances, indicating deterministic light-matter coupling. Our work represents a significant step towards the scalable implementation of coupled quantum emitterresonator systems for highly integrated quantum photonic and plasmonics applications.
We present a new and versatile technique of self-assembly lithography to fabricate a large scale Cadmium selenide quantum dots-silver nanogap metamaterials. After optical and electron microscopic characterizations of the metamaterials, we performed spatially resolved photoluminescence transmission measurements. We obtained highly quenched photoluminescence spectra compared to those from bare quantum dots film. We then quantified the quenching in terms of an average photoluminescence enhancement factor. A finite difference time domain simulation was performed to understand the role of an electric field enhancement in the nanogap over this quenching. Finally, we interpreted the mechanism of the photoluminescence quenching and proposed fabrication method of new metamaterials using our technique.
We report tuning of photoluminescence enhancement and quenching from closed packed monolayers of cadmium selenide quantum dots doped with gold nanoparticles. Plasmon-mediated control of the emission intensity from the monolayers is achieved by varying the size and packing density of the quantum dots as well as the doping concentration of gold nanoparticles. We observe a unique packing density dependent crossover from enhancement to quenching and vice versa for fixed size of quantum dots and doping concentration of gold nanoparticles. We suggest that this behavior is indicative of a crossover from single particle to collective emission from quantum dots mediated by gold nanoparticles.
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