Search

Manipulation of light-matter interaction is critical in modern physics, especially in the strong coupling regime, where the generated half-light, half-matter bosonic quasiparticles as polaritons are important for fundamental quantum science and applications of optoelectronics and nonlinear optics. Two-dimensional transition metal dichalcogenides (TMDs) are ideal platforms to investigate the strong coupling because of their huge exciton binding energy and large absorption coefficients. Further studies on strong exciton-plasmon coupling by combining TMDs with metallic nanostructures have generated broad interests in recent years. However, because of the huge plasmon radiative damping, the observation of strong coupling is significantly limited at room temperature. Here, we demonstrate that a large Rabi splitting (~300 meV) can be achieved at ambient conditions in the strong coupling regime by embedding Ag-WS2 heterostructure in an optical microcavity. The generated quasiparticle with part-plasmon, part-exciton and part-light is analyzed with Hopfield coefficients that are calculated by using three-coupled oscillator model. The resulted plasmon-exciton polaritonic hybrid states can efficiently enlarge the obtained Rabi splitting, which paves the way for the practical applications of polaritonic devices based on ultrathin materials.

Monolayer (1L) transition metal dichalcogenides (TMDCs) have been attracting tremendous interest in recent years as promising candidate materials in atomic-scale optoelectronic devices due to their direct band gaps (1.5–2.2 eV) and strong light—matter interactions. Unfortunately, their practical applications are limited by low visible light absorption stemming from atomic thickness and negligible infrared response. Here, we report the triangular Sb2O3 microresonators in wide thickness and lateral size distributions grown on 1L TMDCs and their created significant broadband enhancement of light adsorption and photoresponse in 1L WSe2 crystal via coexisting Fabry—Perot and whispering gallery type resonances. As an example of demonstration, 1L WSe2 crystal coupled to Sb2O3 microresonators with widely distributed sizes exhibits the enhanced visible light absorption by up to 5 folds and the simultaneously extended near infrared (NIR) one of more than 50%. For application of 1L WSe2 in photodetection, incorporation of Sb2O3 microresonators leads to significantly enhanced visible light responsivity by ∼ 104 order and expanded NIR one of more than 400 mA·W−1. Similar results have been observed in the other 1L W(Mo) dichalcogenides coupled to Sb2O3 microresonators. This work provides a new route for development of the high-performance monolayer TMDCs-based optoelectronic devices. [ABSTRACT FROM AUTHOR]

Through the integration of a strongly coupled plasmonic nanoantenna array with a monolayer MoSe, spatial maps of the photoluminescence (PL) are acquired on- and off-resonance to exhibit the role of the lattice plasmon modes on the enhancement of the PL from the MoSe monolayer. The on-resonance excitation of the hybrid nanostructure at 785 nm reveals a significant PL enhancement of more than 25 (compared to the PL enhancement factor that a Fabry-Perot resonance provides), while the off-resonance excitation at 488 nm only results in an enhancement factor of five. Polarization-resolved optical reflection spectroscopy is also experimented to verify the role of the coupled nanoantenna array on the PL enhancement. Full-wave numerical simulations of the complete structure are also performed to support the observed experimental results. These findings enrich our knowledge regarding the light interaction with 2D materials mediated by plasmonic nanostructures and pave the way for the design of a new class of hybrid 2D material plasmonic devices that utilize enhanced light-matter interaction. [ABSTRACT FROM AUTHOR]

Abstract Heterostructures from two-dimensional transition-metal dichalcogenides MX 2 have emerged as a hot topic in recent years due to their various fascinating properties. Here, we investigated the temperature dependent Raman and photoluminescence (PL) spectra in vertical stacked WS 2 /MoS 2 monolayer heterostructures. Our result shows that both E1 2g and A 1g modes of WS 2 and MoS 2 vary linearly with temperature increasing from 300 to 642 K. The PL measurement also reveals strong temperature dependencies of the PL intensity and peak position. The activation energy of the thermal quenching of the PL emission has been found to be equal to 69.6 meV. The temperature dependence of the peak energy well follows the band-gap shrinkage of bulk semiconductor. [ABSTRACT FROM AUTHOR]

Preferentially exposed active edges are advantageous in the application of two-dimensional materials (2DMs) in high-performance biochemical sensors. Despite current progresses, controllable large-scale production of edge-rich 2DM films for practical applications remains a challenge. In this work, we report the controllable single-step growth of wafer-scale edge-rich WS 2 films of high-density nanoscale multilayer WS 2 islands and their application in sensitive, low detection limit biochemical sensors. The abundant edge active sites are shown to be crucial to their superior biochemical sensing performance. Investigations reveal that high-density edge S-active sites enable the highly sensitive attomolar-level Hg2+ detection as direct target probes via selective Hg-S bonding. Furthermore, 1 fM level selective detection of target viral nucleic acids (RdRp, ORF1ad) are achieved via functionalization of active edge sites with cDNA receptors. Our investigations provide a comprehensive method for application of similar edge-rich 2DM films in high-performance sensors for broad ranges of analytes. • Edge-rich 2D films possess high-density active sites enabling versatile biochemical sensing. • High density edge S-active sites act as probes, enabling sensitive attomolar-level Hg2+ detection. • Edge active sites enable selective functionalization of 2D surface with target specific receptors. • High-sensitivity, selective RNA sensing is achieved with edge-rich WS 2 films. • Evenly distributed, high-density edges enable robust sensing performance. [ABSTRACT FROM AUTHOR]