Enhanced Emission from WSe 2 Monolayers Coupled to Circular Bragg Gratings

Lim

et al. 2020

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Valley polarization is among the most critical attributes of atomically thin materials. However, increasing contrast from monolayer transition metal dichalcogenides (TMDs) has so far been challenging. In this work, a large degree of circular polarization up to 45% from a monolayer WS2 is achieved at room temperature by using a single chiral plasmonic nanoparticle. The increased contrast is attributed to the selective enhancement of both the excitation and the emission rate having one particular handedness of the circular polarization, together with accelerated radiative recombination of valley excitons due to the Purcell effect. The experimental results are corroborated by the optical simulation using the finite‐difference time‐domain (FDTD) method. Additionally, the single chiral nanoparticle enables the observation of valley‐polarized luminescence with a linear excitation. The results provide a promising pathway to enhance valley contrast from monolayer TMDs and utilize them for nanophotonic devices.

Section: Figurementioning

confidence: 99%

A Single Chiral Nanoparticle Induced Valley Polarization Enhancement

Lim

et al. 2020

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Laser & Photonics Reviews

“…This device was found to have multiple lasing peaks at a wavelength range of 600-800 nm and an extremely low threshold of ≈5 W at room temperature. In other aspects, a Si 3 N 4 circular Bragg grating (CBG) structure was selected by Duong et al [162] to integrate with WSe 2 monolayers, in order to promote efficient Purcell-enhanced emission. As seen in Figure 2f, the CBG comprises a nanoscale central disk that is surrounded by periodic ring antennas, whose symmetric feature is utilized to improve the lasing direction.…”

Section: Microdisk Cavity-based Lasersmentioning

confidence: 99%

Hybrid/Integrated Silicon Photonics Based on 2D Materials in Optical Communication Nanosystems

You¹,

Luo²,

Yang³

et al. 2020

Silicon (Si) photonics have established as leading technologies in addressing the rapidly increasing demands of huge data transfer in optical communication systems with compact footprints, small power consumption, and ultradense bandwidth, which are driven by the next generation supercomputers and big data era. Particularly, Si photonics will penetrate into optical communication links at an ever-small scale, namely chip-to-chip and on-chip. However, the nanostructures made of Si with an indirect bandgap are not ideal candidates for on-chip light sources, modulators, and photodetectors, which most-frequently require optical materials with direct bandgap. Thanks to the advent of graphene, transition metal dichalcogenides and other two-dimensional (2D) materials, which can facilitate extraordinary progresses in improving device performance at the ultrathin scale, their integration with Si photonics furnishes a heterogeneous platform to construct fully functional and highly integrated photonic communication systems. In this work, the current advancements in the on-chip applications of Si photonics-2D materials heterostructures, inclusive of all essential chip-scale modules and integrated circuits, as well as the future prospective and challenges are reviewed and discussed. The present study sets out to objectively measure the feasibility of the hybrid integration between Si photonics and 2D materials in on-chip optical communications and the advanced applications beyond.

Comptes Rendus. Physique

“…A circular Bragg grating (CBG), also referred to as a 'bullseye' cavity, has been successfully utilized in III-V quantum photonics to yield efficient single photon sources [18] and pair sources [19]. Recently, a first step towards the integration of atomically thin WSe 2 with a CBG has been discussed [20], where enhanced emission was observed from a monolayer. However, the experiments were conducted in the spectral range around 750 nm, where the emission of WSe 2 monolayers is usually dominated by a broad defect band at cryogenic temperatures, rather then the excitonic or trionic resonances located close to 720 nm [21].…”

Section: Introductionmentioning

confidence: 99%

Hyperspectral study of the coupling between trions in WSe 2 monolayers to a circular Bragg grating cavity

Iff¹,

Davanço²,

Betzold³

et al. 2022

Circular Bragg gratings compose a very appealing photonic platform and nanophotonic interface for the controlled light-matter coupling of emitters in nanomaterials. Here, we discuss the integration of exfoliated monolayers of WSe 2 with GaInP Bragg gratings. We apply hyperspectral imaging to our coupled system, and explore the spatio-spectral characteristics of our coupled monolayer-cavity system. Our work represents a valuable step towards the integration of atomically thin quantum emitters in semiconductor nanophotonic cavities.