Browse
Submit Data
Databases
API
Help

Dataset Information

25 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Giant All-Optical Modulation of Second-Harmonic Generation Mediated by Dark Excitons.

ABSTRACT: All-optical control of nonlinear photonic processes in nanomaterials is of significant interest from a fundamental viewpoint and with regard to applications ranging from ultrafast data processing to spectroscopy and quantum technology. However, these applications rely on a high degree of control over the nonlinear response, which still remains elusive. Here, we demonstrate giant and broadband all-optical ultrafast modulation of second-harmonic generation (SHG) in monolayer transition-metal dichalcogenides mediated by the modified excitonic oscillation strength produced upon optical pumping. We reveal a dominant role of dark excitons to enhance SHG by up to a factor of ∼386 at room temperature, 2 orders of magnitude larger than the current state-of-the-art all-optical modulation results. The amplitude and sign of the observed SHG modulation can be adjusted over a broad spectral range spanning a few electronvolts with ultrafast response down to the sub-picosecond scale via different carrier dynamics. Our results not only introduce an efficient method to study intriguing exciton dynamics, but also reveal a new mechanism involving dark excitons to regulate all-optical nonlinear photonics.

SUBMITTER: Wang Y

PROVIDER: S-EPMC8377711 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Direct probing of contact electrification by using optical second harmonic generation technique.

Project description:Contact electrification between two different materials is one of the oldest fields of study in solid-state physics. Here, we introduced an innovative system based on optical electric-field-induced second harmonic generation (EFI-SHG) technique that can directly monitor the dynamic performance of the contact electrification on the surface of polyimide film. After the contact, the EFI-SHG system visualized briefly three relaxations of the tribo-induced charges on the surface of a polyimide film, a fast relaxation within 3 min followed by two much slower relaxations, which were possibly related to different charge diffusion routes. The contact electrification under several special experimental conditions (wind, water and steam) was studied to demonstrate the high flexibility and material selectivity of the EFI-SHG. The EFI-SHG studies confirmed the motion of the water can remove the surface charge, while the appearance and the evaporation of a thin water layer cannot enhance the charge diffusion. We anticipate that this experimental technique will find a variety of applications in the field of contact electrification and the development of the recently invented triboelectric nano generator.

| S-EPMC4536524 | biostudies-literature

Multipolar Effects in the Optical Active Second Harmonic Generation from Sawtooth Chiral Metamaterials.

Project description:Based on the facts that chiral molecules response differently to left- and right-handed circular polarized light, chiroptical effects are widely employed for determining structure chirality, detecting enantiomeric excess, or controlling chemical reactions of molecules. Compared to those in natural materials, chiroptical behaviors can be significantly amplified in chiral plasmonic metamaterials due to the concentrated local fields in the structure. The on-going research towards giant chiroptical effects in metamaterial generally focus on optimizing the field-enhancement effects. However, the observed chiroptical effects in metamaterials rely on more complicated factors and various possibilities towards giant chiroptical effects remains unexplored. Here we study the optical-active second harmonic generation (SHG) behaviors in a pair of planar sawtooth gratings with mirror-imaged patterns. Significant multipolar effects were observed in the polarization-dependent SHG curves. We show that the chirality of the nanostructure not only give rise to nonzero chiral susceptibility tensor components within the electric-dipole approximation, but also lead to different levels of multipolar interactions for the two orthogonal circular polarizations that further enhance the nonlinear optical activity of the material. Our results thus indicate novel ways to optimize nonlinear plasmonic structures and achieve giant chiroptical response via multipolar interactions.

| S-EPMC4766511 | biostudies-literature

Deciphering second harmonic generation signals.

Project description:Second harmonic generation (SHG) has emerged as one of the most powerful techniques used to selectively monitor surface dynamics and reactions for all types of interfaces as well as for imaging non-centrosymmetric structures, although the molecular origin of the SHG signal is still poorly understood. Here, we present a breakthrough approach to predict and interpret the SHG signal at the atomic level, which is freed from the hyperpolarisability concept and self-consistently considers the non-locality and the coupling with the environment. The direct ab initio method developed here shows that a bulk quadrupole contribution significantly overwhelms the interface dipole term in the purely interfacial induced second-order polarisation for water/air interfaces. The obtained simulated SHG responses are in unprecedented agreement with the experimental signal. This work not only paves the road for the prediction of SHG response from more complex interfaces of all types, but also suggests new insights in the interpretation of the SHG signal at a molecular level. In particular, it highlights the modest influence of the molecular orientation and the high significance of the bulk quadrupole contribution, which does not depend on the interface, in the total experimental response.

| S-EPMC8612378 | biostudies-literature

Optical second harmonic generation microscopy: application to the sensitive detection of cell membrane damage.

Project description:Optical second harmonic generation (SHG) is a nonlinear optical process which is sensitive to the symmetry of media. SHG microscopy allows for selective probing of a non-centrosymmetric area of sample. This type of nonlinear optical microscope was first used to observe ferroelectric domains and has been applied to various specimens including the biological samples to date. Imaging of the endogenous SHG of biological tissue has been utilized for the selective observation of filament systems in tissues such as collagen, myosin, and microtubules, which exhibit a polar structure. The cellular membrane can be selectively observed by the SHG microscope through membrane staining with amphiphilic polar dye molecules. It has been reported that, by imaging exogenous SHG of the membrane, sensitive detection of membrane damage could be realized using the SHG microscope. Because the staining dye is fluorescent, both SHG and two-photon excited fluorescence (TPF) images can be obtained simultaneously. How the SHG intensity depends on the molecular alignment of the polar dye molecules that reflects the ordering of lipid molecules in the plasma membrane and the necessity of the normalization of the SHG intensity by the TPF intensity is discussed. Furthermore, the assessment of the membrane damage induced by exposing polycation to HeLa cells has been compared with the conventional cytotoxicity and cell viability tests to demonstrate the higher sensitivity of the present SHG-based assay.

| S-EPMC6557941 | biostudies-literature

Lithium niobate particles with a tunable diameter and porosity for optical second harmonic generation.

Project description:Uniform, porous particles of lithium niobate (LiNbO3) can be used as contrast agents in bioimaging, drug delivery carriers, nonlinear optical emitters, biosensors, photocatalysts and electrode materials in lithium-ion batteries. In this article, we introduce a hydrothermal method to prepare uniform, mesoporous LiNbO3 particles with a tunable diameter and porosity. These properties are each tuned by adjusting the reaction times of the hydrothermal process. This approach forms mesoporous LiNbO3 particles without the addition of organic additives (e.g., surfactants) or hard templates (e.g., silica). Formation of these LiNbO3 particles proceeds through an aqueous sol-gel reaction in which niobium hydroxide species are generated in situ and undergo a condensation reaction in the presence of lithium hydroxide to form a colloidal solution. A hydrothermal reaction using this solution resulted in the formation of uniform, solid, and semi-crystalline particles. A post-calcination step induces crystallinity in the product and transforms the particles into mesoporous materials composed of a rhombohedral LiNbO3 phase. An increase in reaction time results in an increase in the diameter of these particles from 580 to 1850 nm, but also decreases their porosity. These LiNbO3 particles were active towards second harmonic generation (SHG), and their SHG response resembled that of larger crystals of rhombohedral LiNbO3. This work also offers a viable strategy for manufacturing other materials (e.g., tantalates, titanates, niobates) with tunable dimensions and porosity that enable a broad range of applications in photonics, energy, and catalysis.

| S-EPMC8979055 | biostudies-literature

Near-field enhancement of optical second harmonic generation in hybrid gold-lithium niobate nanostructures.

Project description:Nanophotonics research has focused recently on the ability of nonlinear optical processes to mediate and transform optical signals in a myriad of novel devices, including optical modulators, transducers, color filters, photodetectors, photon sources, and ultrafast optical switches. The inherent weakness of optical nonlinearities at smaller scales has, however, hindered the realization of efficient miniaturized devices, and strategies for enhancing both device efficiencies and synthesis throughput via nanoengineering remain limited. Here, we demonstrate a novel mechanism by which second harmonic generation, a prototypical nonlinear optical phenomenon, from individual lithium niobate particles can be significantly enhanced through nonradiative coupling to the localized surface plasmon resonances of embedded gold nanoparticles. A joint experimental and theoretical investigation of single mesoporous lithium niobate particles coated with a dispersed layer of ~10 nm diameter gold nanoparticles shows that a ~32-fold enhancement of second harmonic generation can be achieved without introducing finely tailored radiative nanoantennas to mediate photon transfer to or from the nonlinear material. This work highlights the limitations of current strategies for enhancing nonlinear optical phenomena and proposes a route through which a new class of subwavelength nonlinear optical platforms can be designed to maximize nonlinear efficiencies through near-field energy exchange.

| S-EPMC10130160 | biostudies-literature

Giant optical nonlinearities from Rydberg excitons in semiconductor microcavities.

Project description:The realization of exciton polaritons-hybrid excitations of semiconductor quantum well excitons and cavity photons-has been of great technological and scientific significance. In particular, the short-range collisional interaction between excitons has enabled explorations into a wealth of nonequilibrium and hydrodynamical effects that arise in weakly nonlinear polariton condensates. Yet, the ability to enhance optical nonlinearities would enable quantum photonics applications and open up a new realm of photonic many-body physics in a scalable and engineerable solid-state environment. Here we outline a route to such capabilities in cavity-coupled semiconductors by exploiting the giant interactions between excitons in Rydberg states. We demonstrate that optical nonlinearities in such systems can be vastly enhanced by several orders of magnitude and induce nonlinear processes at the level of single photons.

| S-EPMC5883042 | biostudies-literature

Second Harmonic Generation of Unpolarized Light.

Project description:A Mueller tensor mathematical framework was applied for predicting and interpreting the second harmonic generation (SHG) produced with an unpolarized fundamental beam. In deep tissue imaging through SHG and multiphoton fluorescence, partial or complete depolarization of the incident light complicates polarization analysis. The proposed framework has the distinct advantage of seamlessly merging the purely polarized theory based on the Jones or Cartesian susceptibility tensors with a more general Mueller tensor framework capable of handling partial depolarized fundamental and/or SHG produced. The predictions of the model are in excellent agreement with experimental measurements of z-cut quartz and mouse tail tendon obtained with polarized and depolarized incident light. The polarization-dependent SHG produced with unpolarized fundamental allowed determination of collagen fiber orientation in agreement with orthogonal methods based on image analysis. This method has the distinct advantage of being immune to birefringence or depolarization of the fundamental beam for structural analysis of tissues.

| S-EPMC5801736 | biostudies-literature

Second harmonic generation microscopy in zebrafish.

Project description:Modern optical imaging has progressed rapidly with the ability to noninvasively image cellular and subcellular phenomena with high spatial and temporal resolution. In particular, emerging techniques such as second harmonic generation (SHG) microscopy can allow for the monitoring of intrinsic contrast, such as that from collagen, in live and fixed samples. When coupled with multiphoton fluorescence microscopy, SHG can be used to image interactions between cells and the surrounding extracellular environment. There is recent interest in using these approaches to study inflammation and wound healing in zebrafish, an important model for studying these processes. In this chapter we present the practical aspects of using second harmonic generation to image interactions between leukocytes and collagen during wound healing in zebrafish.

| S-EPMC5489409 | biostudies-literature

Interlayer exciton mediated second harmonic generation in bilayer MoS<sub>2</sub>.

Project description:Second-harmonic generation (SHG) is a non-linear optical process, where two photons coherently combine into one photon of twice their energy. Efficient SHG occurs for crystals with broken inversion symmetry, such as transition metal dichalcogenide monolayers. Here we show tuning of non-linear optical processes in an inversion symmetric crystal. This tunability is based on the unique properties of bilayer MoS2, that shows strong optical oscillator strength for the intra- but also interlayer exciton resonances. As we tune the SHG signal onto these resonances by varying the laser energy, the SHG amplitude is enhanced by several orders of magnitude. In the resonant case the bilayer SHG signal reaches amplitudes comparable to the off-resonant signal from a monolayer. In applied electric fields the interlayer exciton energies can be tuned due to their in-built electric dipole via the Stark effect. As a result the interlayer exciton degeneracy is lifted and the bilayer SHG response is further enhanced by an additional two orders of magnitude, well reproduced by our model calculations. Since interlayer exciton transitions are highly tunable also by choosing twist angle and material combination our results open up new approaches for designing the SHG response of layered materials.

| S-EPMC8617052 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data