scholarly journals Exciton-dielectric mode coupling in MoS2 nanoflakes visualized by cathodoluminescence

Nanophotonics ◽  
2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Dung Thi Vu ◽  
Nikolaos Matthaiakakis ◽  
Hikaru Saito ◽  
Takumi Sannomiya
Keyword(s):  
Light Emission ◽  
Single Photon ◽  
Transition Metal Dichalcogenides ◽  
High Refractive Index ◽  
Scanning Transmission Electron Microscope ◽  
Optical Responses ◽  
Single Photon Emitters ◽  
Scanning Transmission ◽  
Metal Dichalcogenides ◽  
Energy Conversion Devices

Abstract Two-dimensional (2D) transition metal dichalcogenides (TMDCs), possessing unique exciton luminescence properties, have attracted significant attention for use in optical and electrical devices. TMDCs are also high refractive index materials that can strongly confine the electromagnetic field in nanoscale dimensions when patterned into nanostructures, thus resulting in complex light emission that includes exciton and dielectric resonances. Here, we use cathodoluminescence (CL) to experimentally visualize the emission modes of single molybdenum disulfide (MoS2) nanoflakes and to investigate luminescence enhancement due to dielectric resonances in nanoscale dimensions, by using a scanning transmission electron microscope. Specifically, we identify dielectric modes whose resonant wavelength is sensitive to the shape and size of the nanoflake, and exciton emission peaks whose energies are insensitive to the geometry of the flakes. Using a four-dimensional CL method and boundary element method simulations, we further theoretically and experimentally visualize the emission polarization and angular emission patterns, revealing the coupling of the exciton and dielectric resonant modes. Such nanoscopic observation provides a detailed understanding of the optical responses of MoS2 including modal couplings of excitons and dielectric resonances which play a crucial role in the development of energy conversion devices, single-photon emitters, and nanophotonic circuits with enhanced light-matter interactions.

scholarly journals Site-Controlled Telecom Single-Photon Emitters in Atomically-thin MoTe2

2021 ◽  
Author(s):  
Huan Zhao ◽  
Michael Pettes ◽  
Yu Zheng ◽  
Han Htoon
Keyword(s):  
Single Photon ◽  
Transition Metal Dichalcogenides ◽  
Zeeman Splitting ◽  
Single Photons ◽  
Layer By Layer ◽  
Single Photon Emitters ◽  
Anisotropic Exchange Interaction ◽  
Pillar Arrays ◽  
Linearly Polarized ◽  
Metal Dichalcogenides

Abstract Quantum emitters (QEs) in two-dimensional transition metal dichalcogenides (2D TMDCs) have advanced to the forefront of quantum communication and transduction research1 due to their unique potentials in accessing valley pseudo-spin degree of freedom (DOF)2 and facile integration into quantum-photonic, electronic and sensing platforms via the layer-by-layer-assembly approach.3 To date, QEs capable of operating in O-C telecommunication bands have not been demonstrated in TMDCs.4-7 Here we report a deterministic creation of such telecom QEs emitting over the 1080 to 1550 nm wavelength range via coupling of 2D molybdenum ditelluride (MoTe2) to strain inducing nano-pillar arrays.8,9 Our Hanbury Brown and Twiss experiment conducted at 10 K reveals clear photon antibunching with 90% single photon purity. Ultra-long lifetimes, 4-6 orders of magnitude longer than that of the 2D exciton, are also observed. Polarization analysis further reveals that while some QEs display cross-linearly polarized doublets with ~1 meV splitting resulting from the strain induced anisotropic exchange interaction, valley degeneracy is preserved in other QEs. Valley Zeeman splitting as well as restoring of valley symmetry in cross-polarized doublets are observed under 8T magnetic field. In contrast to other telecom QEs,10-12 our QEs which offer the potential to access valley DOF through single photons, could lead to unprecedented advantages in optical fiber-based quantum networks.

scholarly journals Optical properties of atomically thin transition metal dichalcogenides: observations and puzzles

Nanophotonics ◽  
2017 ◽  
Vol 6 (6) ◽  
pp. 1289-1308 ◽  
Author(s):  
Maciej Koperski ◽  
Maciej R. Molas ◽  
Ashish Arora ◽  
Karol Nogajewski ◽  
Artur O. Slobodeniuk ◽  
...  
Keyword(s):  
Optical Properties ◽  
Transition Metal ◽  
Optical Pumping ◽  
Single Photon ◽  
Hexagonal Boron Nitride ◽  
Transition Metal Dichalcogenides ◽  
Wide Band ◽  
Open Questions ◽  
Single Photon Emitters ◽  
Metal Dichalcogenides

AbstractRecent results on the optical properties of monolayer and few layers of semiconducting transition metal dichalcogenides are reviewed. Experimental observations are presented and discussed in the frame of existing models, highlighting the limits of our understanding in this emerging field of research. We first introduce the representative band structure of these systems and their interband optical transitions. The effect of an external magnetic field is then considered to discuss Zeeman spectroscopy and optical pumping experiments, both revealing phenomena related to the valley degree of freedom. Finally, we discuss the observation of single photon emitters in different types of layered materials, including wide band gap hexagonal boron nitride. While going through these topics, we try to focus on open questions and on experimental observations, which do not yet have a clear explanation.

scholarly journals Site-Controlled Telecom Single-Photon Emitters in Atomically-thin MoTe2

2021 ◽  
Author(s):  
Huan Zhao ◽  
Micahel Pettes ◽  
Yu Zheng ◽  
Han Htoon
Keyword(s):  
Single Photon ◽  
Transition Metal Dichalcogenides ◽  
Zeeman Splitting ◽  
Liquid Nitrogen Temperature ◽  
Single Photon Emitters ◽  
Anisotropic Exchange Interaction ◽  
Pillar Arrays ◽  
Anisotropic Exchange ◽  
Linearly Polarized ◽  
Metal Dichalcogenides

Abstract Quantum emitters (QEs) in two-dimensional transition metal dichalcogenides (2D TMDCs) have advanced to the forefront of quantum communication and transduction research1. To date, QEs capable of operating in O-C telecommunication bands have not been demonstrated in TMDCs.2-5 Here we report a deterministic creation of such telecom QEs emitting over the 1080 to 1550 nm wavelength range via coupling of 2D molybdenum ditelluride (MoTe2) to strain inducing nano-pillar arrays.6, 7 Our Hanbury Brown and Twiss experiment conducted at 10 K reveals clear photon antibunching with 90% single photon purity. The photon antibuching can be observed up to liquid nitrogen temperature (77 K). Polarization analysis further reveals that while some QEs display cross-linearly polarized doublets with ~1 meV splitting resulting from the strain induced anisotropic exchange interaction, valley degeneracy is preserved in other QEs. Valley Zeeman splitting as well as restoring of valley symmetry in cross-polarized doublets are observed under 8T magnetic field.

scholarly journals Integration of single photon emitters in 2D layered materials with a silicon nitride photonic chip

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Frédéric Peyskens ◽  
Chitraleema Chakraborty ◽  
Muhammad Muneeb ◽  
Dries Van Thourhout ◽  
Dirk Englund
Keyword(s):  
Silicon Nitride ◽  
Integrated Circuits ◽  
Large Scale ◽  
Single Photon ◽  
Transition Metal Dichalcogenides ◽  
Building Blocks ◽  
Single Photon Emitters ◽  
Metal Dichalcogenides ◽  
On Chip ◽  
Scale Integration

Abstract Photonic integrated circuits (PICs) enable the miniaturization of optical quantum circuits because several optic and electronic functionalities can be added on the same chip. Integrated single photon emitters (SPEs) are central building blocks for such quantum photonic circuits. SPEs embedded in 2D transition metal dichalcogenides have some unique properties that make them particularly appealing for large-scale integration. Here we report on the integration of a WSe2 monolayer onto a Silicon Nitride (SiN) chip. We demonstrate the coupling of SPEs with the guided mode of a SiN waveguide and study how the on-chip single photon extraction can be maximized by interfacing the 2D-SPE with an integrated dielectric cavity. Our approach allows the use of optimized PIC platforms without the need for additional processing in the SPE host material. In combination with improved wafer-scale CVD growth of 2D materials, this approach provides a promising route towards scalable quantum photonic chips.

scholarly journals Site-controlled telecom-wavelength single-photon emitters in atomically-thin MoTe2

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Huan Zhao ◽  
Michael T. Pettes ◽  
Yu Zheng ◽  
Han Htoon
Keyword(s):  
Single Photon ◽  
Transition Metal Dichalcogenides ◽  
Zeeman Splitting ◽  
Liquid Nitrogen Temperature ◽  
Single Photon Emitters ◽  
Anisotropic Exchange Interaction ◽  
Pillar Arrays ◽  
Linearly Polarized ◽  
Metal Dichalcogenides ◽  
Photon Antibunching

AbstractQuantum emitters (QEs) in two-dimensional transition metal dichalcogenides (2D TMDCs) have advanced to the forefront of quantum communication and transduction research. To date, QEs capable of operating in O-C telecommunication bands have not been demonstrated in TMDCs. Here we report site-controlled creation of telecom QEs emitting over the 1080 to 1550 nm telecommunication wavelength range via coupling of 2D molybdenum ditelluride (MoTe2) to strain inducing nano-pillar arrays. Hanbury Brown and Twiss experiments conducted at 10 K reveal clear photon antibunching with 90% single-photon purity. The photon antibunching can be observed up to liquid nitrogen temperature (77 K). Polarization analysis further reveals that while some QEs display cross-linearly polarized doublets with ~1 meV splitting resulting from the strain induced anisotropic exchange interaction, valley degeneracy is preserved in other QEs. Valley Zeeman splitting as well as restoring of valley symmetry in cross-polarized doublets are observed under 8 T magnetic field.

Single Photon Sources in Atomically Thin Materials

2019 ◽  
Vol 70 (1) ◽  
pp. 123-142 ◽  
Author(s):  
Milos Toth ◽  
Igor Aharonovich
Keyword(s):  
Light Emission ◽  
Single Photon ◽  
Hexagonal Boron Nitride ◽  
Transition Metal Dichalcogenides ◽  
Proof Of Concept ◽  
Scientific Discussion ◽  
Two Dimensional Materials ◽  
Metal Dichalcogenides ◽  
On Chip ◽  
Potential Use

Layered materials are very attractive for studies of light–matter interactions at the nanoscale. In particular, isolated quantum systems such as color centers and quantum dots embedded in these materials are gaining interest due to their potential use in a variety of quantum technologies and nanophotonics. Here, we review the field of nonclassical light emission from van der Waals crystals and atomically thin two-dimensional materials. We focus on transition metal dichalcogenides and hexagonal boron nitride and discuss the fabrication and properties of quantum emitters in these systems and proof-of-concept experiments that provide a foundation for their integration in on-chip nanophotonic circuits. These experiments include tuning of the emission wavelength, electrical excitation, and coupling of the emitters to waveguides, dielectric cavities, and plasmonic resonators. Finally, we discuss current challenges in the field and provide an outlook to further stimulate scientific discussion.

scholarly journals Atomic lattice disorder in charge-density-wave phases of exfoliated dichalcogenides (1T-TaS2)

2016 ◽  
Vol 113 (41) ◽  
pp. 11420-11424 ◽  
Author(s):  
Robert Hovden ◽  
Adam W. Tsen ◽  
Pengzi Liu ◽  
Benjamin H. Savitzky ◽  
Ismail El Baggari ◽  
...  
Keyword(s):  
Charge Density ◽  
Density Wave ◽  
Transition Metal Dichalcogenides ◽  
Charge Density Waves ◽  
Periodic Lattice ◽  
Atomic Lattice ◽  
Scanning Transmission ◽  
Out Of Plane ◽  
Metal Dichalcogenides ◽  
Layered Transition Metal

Charge-density waves (CDWs) and their concomitant periodic lattice distortions (PLDs) govern the electronic properties in several layered transition-metal dichalcogenides. In particular, 1T-TaS2 undergoes a metal-to-insulator phase transition as the PLD becomes commensurate with the crystal lattice. Here we directly image PLDs of the nearly commensurate (NC) and commensurate (C) phases in thin, exfoliated 1T-TaS2 using atomic resolution scanning transmission electron microscopy at room and cryogenic temperature. At low temperatures, we observe commensurate PLD superstructures, suggesting ordering of the CDWs both in- and out-of-plane. In addition, we discover stacking transitions in the atomic lattice that occur via one-bond-length shifts. Interestingly, the NC PLDs exist inside both the stacking domains and their boundaries. Transitions in stacking order are expected to create fractional shifts in the CDW between layers and may be another route to manipulate electronic phases in layered dichalcogenides.

scholarly journals MoS2 with Stable Photoluminescence Enhancement under Stretching via Plasmonic Surface Lattice Resonance

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1698
Author(s):  
Yen-Ju Chiang ◽  
Tsan-Wen Lu ◽  
Pin-Ruei Huang ◽  
Shih-Yen Lin ◽  
Po-Tsung Lee
Keyword(s):  
Transition Metal ◽  
Light Emission ◽  
Transition Metal Dichalcogenides ◽  
Plasmonic Nanostructures ◽  
Large Area ◽  
Mos2 Monolayer ◽  
Surface Lattice ◽  
Metal Dichalcogenides ◽  
Photoluminescence Enhancement

In this study, by combining a large-area MoS2 monolayer with silver plasmonic nanostructures in a deformable polydimethylsiloxane substrate, we theoretically and experimentally studied the photoluminescence (PL) enhancement of MoS2 by surface lattice resonance (SLR) modes of different silver plasmonic nanostructures. We also observed the stable PL enhancement of MoS2 by silver nanodisc arrays under differently applied stretching strains, caused by the mechanical holding effect of the MoS2 monolayer. We believe the results presented herein can guarantee the possibility of stably enhancing the light emission of transition metal dichalcogenides using SLR modes in a deformable platform.

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