Spectroscopy and Biosensing with Optically Resonant Dielectric Nanostructures

Krasnok, Alex; Caldarola, Martín; Bonod, Nicolas; Alù, Andrea

doi:10.1002/adom.201701094

Cited by 131 publications

(126 citation statements)

References 338 publications

(597 reference statements)

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“…The metasurface chirality in plane allows valley-selective spinmomentum locked propagation of the PL signal ( Figure 3b). Moreover, it has been shown that the proposed resonant metasurface shows a coupling regime, which is very close to the strong couplings [86,87] with Rabi splitting energy of 40 meV at the crossing point (A-exciton emission energy, 2.01 eV) between the uncoupled exciton and the surface mode of the metasurface. As a result, the entire structure forms hybrid exciton-photon quasiparticles (referred to as chiralitons).…”

Section: Metasurfacessupporting

confidence: 58%

Valley-Selective Response of Nanostructures Coupled to 2D Transition-Metal Dichalcogenides

Krasnok

Alù

2018

Applied Sciences

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Monolayer (1L) transition metal dichalcogenides (TMDCs) are attractive materials for several optoelectronic applications because of their strong excitonic resonances and valley-selective response. Valley excitons in 1L-TMDCs are formed at opposite points of the Brillouin zone boundary, giving rise to a valley degree of freedom that can be treated as a pseudospin and may be used as a platform for information transport and processing. However, short valley depolarization times and relatively short exciton lifetimes at room temperature prevent using valley pseudospin in on-chip integrated valley devices. Recently it has been demonstrated how coupling these materials to optical nanoantennas and metasurfaces can overcome this obstacle. Here, we review the state-of-theart advances in valley-selective directional emission and exciton sorting in 1L-TMDC mediated by nanostructures and nanoantennas. We briefly discuss the optical properties of 1L-TMDCs paying special attention to their photoluminescence/absorption spectra, dynamics of valley depolarization and valley Hall effect. Then, we review recent works on nanostructures for valley-selective directional emission from 1L-TMDCs.(TMDCs) [1][2][3][4][5][6][7][8][9][10]. Monolayer TMDCs are formed ( Figure 1a) by a hexagonal network of transition metal atoms (M: Mo, W) hosted between two hexagonal lattices of chalcogenide atoms (X: S, Se).Electronically, 1L-TMDCs behave as two-dimensional semiconductors, with bandgaps lying in the visible and near-IR range. In the monolayer limit, the bandgaps of these materials are direct, enabling enhanced interactions of dipole transitions with light. An essential property of 1L-TMDCs is the broken inversion symmetry of their hexagonal 2D crystals, which, in combination with time-reversal symmetry, leads to opposite spins at the +K and -K valleys, effectively locking the spin and valley degrees of freedom (pseudospin or Berry curvature) [11][12][13]. Optical manipulation of the valley degree of freedom can be realized via exciton resonances based on the valley contrasting optical selection rules (for instance with  σ and  σ light excitation). The unique opportunity of addressing valley index make it possible to explore this binary quantum degree of freedom as an alternative information carrier [7,14,15], which may complement both classical and quantum computing schemes based on charge and spin. However, short valley depolarization times and relatively short exciton lifetimes at room temperature prevent using valley pseudospin in on-chip integrated valley devices. Recently it has been demonstrated how coupling these materials to optical nanoantennas and metasurfaces can overcome this obstacle. It has been demonstrated that resonant optical nanostructures and nanoantennas can effectively enhance and direct the emission from opposite valleys in 1L-TMDCs into different directions [16-19]. The proposed nanostructures for valley-selective directional emission can be divided into two groups: nanostructures for spatial separation of valley de...

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Section: Metasurfacessupporting

confidence: 58%

Valley-Selective Response of Nanostructures Coupled to 2D Transition-Metal Dichalcogenides

Krasnok

Alù

2018

Applied Sciences

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“…Thus, for further analysis we assume the excitons to be incoherent. Next, the number of excitons N is proportional to the tangential electric field intensity ( 2 || t E ) on the TMDC surface for a given internal quantum efficiency [31]. Thus, enhanced local electric field intensity induces an increase in the number of excitons involved in the light-matter interaction process.…”

Section: Resultsmentioning

confidence: 99%

Enhanced excitation and emission from 2D transition metal dichalcogenides with all-dielectric nanoantennas

2019

Self Cite

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The recently emerged concept of all-dielectric nanophotonics based on optical Mie resonances in highindex dielectric nanoparticles has proven a promising pathway to boost light-matter interactions at the nanoscale. In this work, we discuss the opportunities enabled by the interaction of dielectric nanoresonators with 2D transition metal dichalcogenides (2D TMDCs), leading to weak and strong coupling regimes. We perform a comprehensive analysis of bright exciton photoluminescence (PL) enhancement from various 2D TMDCs, including WS2, MoS2, WSe2, and MoSe2 via their coupling to Mie resonances of a silicon nanoparticle. For each case, we find the system parameters corresponding to maximal PL enhancement taking into account excitation rate, Purcell factor and radiation efficiency.We demonstrate numerically that all-dielectric Si nanoantennas can significantly enhance the PL intensity from 2D TMDC by a factor of hundred through precise optimization of the geometrical and material parameters. Our results may be useful for high-efficiency 2D TMDC-based optoelectronic, nanophotonic, and quantum optical devices.

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“…Furthermore, dielectric nanostrutures can exhibit both electric and magnetic multipolar modes, which further diversifies the engineering options allowing to tailor their response towards specific effects or applications. As such, Mie-resonant dielectric nanostructures have gained immense popularity in recent years, and many potential applications including enhancing light-matter interactions [11], energy harvesting [12], and efficient wavefront shaping devices [13] were suggested. Integrating 2D-TMDs with Mie-resonant dielectric nanostructures yields hybrid entities which may find applications as novel active nanophotonic platforms and provides interesting routes to harness the unique properties of these molecularly thin materials at the nanoscale.…”

Section: Introductionmentioning

confidence: 99%

Integration of two-dimensional transition metal dichalcogenides with Mie-resonant dielectric nanostructures

Mupparapu

Bucher

Staude

2020

Advances in Physics: X

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Integrating transition metal dichalcogenide (TMD) monolayers with dielectric nanostructures exhibiting Mie-like resonances opens a plethora of opportunities in manipulating their excitonic emission in the near-field and far-field regimes, yielding interactions spanning from weak to strong coupling regimes, and routing valley polarized chiral emission, to name just a few. Moreover, there is a completely new path unraveled recently by realizing dielectric resonators directly from TMDs, thus combining scatterer and emitter into a single entity. This hybrid configuration is promising to realize integrated active meta-optical devices in a facile manner. In this review article, we provide an overview of the state of the art on integrating monolayers of TMDs with Mieresonant photonic nanostructures. ARTICLE HISTORY

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Spectroscopy and Biosensing with Optically Resonant Dielectric Nanostructures

Cited by 131 publications

References 338 publications

Valley-Selective Response of Nanostructures Coupled to 2D Transition-Metal Dichalcogenides

Valley-Selective Response of Nanostructures Coupled to 2D Transition-Metal Dichalcogenides

Enhanced excitation and emission from 2D transition metal dichalcogenides with all-dielectric nanoantennas

Integration of two-dimensional transition metal dichalcogenides with Mie-resonant dielectric nanostructures

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