A5091041752- 2D Materials and Applications
- Mechanical and Optical Resonators
- Advanced Fiber Laser Technologies
- Perovskite Materials and Applications
- Photonic and Optical Devices
- Quantum Dots Synthesis And Properties
- Neural Networks and Reservoir Computing
- Graphene research and applications
- Spectroscopy and Quantum Chemical Studies
- Photorefractive and Nonlinear Optics
- Molecular Junctions and Nanostructures
- Semiconductor Quantum Structures and Devices
- Strong Light-Matter Interactions
- Spectroscopy Techniques in Biomedical and Chemical Research
- Chalcogenide Semiconductor Thin Films
- Plasmonic and Surface Plasmon Research
- Advanced Fluorescence Microscopy Techniques
- Thermal Radiation and Cooling Technologies
- Thermal properties of materials
- Quantum Information and Cryptography
- Quantum and electron transport phenomena
- Nanowire Synthesis and Applications
- Advanced Fiber Optic Sensors
- Advanced Memory and Neural Computing
- Crystal Structures and Properties
Columbia University
2020-2025
Politecnico di Milano
2017-2025
Institute of Structure of Matter
2023
Scuola Normale Superiore
2023
Parc Científic de la Universitat de València
2023
Instituto de Ciencia de Materiales de Sevilla
2023
Center for Nanotechnology Innovation
2023
Italian Institute of Technology
2023
University of Cambridge
2019
We present a transient absorption setup combining broadband detection over the visible–UV range with high temporal resolution (∼20 fs) which is ideally suited to trigger and detect vibrational coherences in different classes of materials. generate coherent phonons (CPs) single-layer (1L)-MoS2, as representative semiconducting 1L-transition metal dichalcogenide (TMD), where confined dynamical interaction between excitons unexplored. The oscillatory motion out-of-plane A′1 phonons, triggered...
Many promising optoelectronic devices, such as broadband photodetectors, nonlinear frequency converters, and building blocks for data communication systems, exploit photoexcited charge carriers in graphene. For these it is essential to understand the relaxation dynamics after photoexcitation. These contain a sub-100 fs thermalization phase, which occurs through carrier-carrier scattering leads carrier distribution with an elevated temperature. This followed by picosecond cooling where...
Monolayer transition metal dichalcogenides bear great potential for photodetection and light harvesting due to high absorption coefficients. However, these applications require dissociation of strongly bound photogenerated excitons. The can be achieved by vertically stacking different monolayers realize band alignment that favors interlayer charge transfer. In such heterostructures, the reported recombination times vary strongly, separation mechanisms remain elusive. We use two color...
Abstract Nonlinear optics is of crucial importance in several fields science and technology with applications frequency conversion, entangled‐photon generation, self‐referencing combs, crystal characterization, sensing, ultra‐short light pulse generation characterization. In recent years, layered materials related heterostructures have attracted huge attention this field, due to their nonlinear optical susceptibilities, ease integration on photonic platforms, 2D nature which relaxes the...
Abstract Charge transfer processes in two-dimensional van der Waals heterostructures enable upconversion of low energy photons and efficient charge carriers extraction. Here we use broadband ultrafast optical spectroscopy to track dynamics large-area 2D made epitaxial single-layer tungsten disulfide (WS 2 ) grown by chemical vapour deposition on graphene. Selective carrier photoexcitation graphene, with tunable near-infrared photon energies as 0.8 eV (i.e. lower than half the bandgap WS ),...
In single-layer (1L) transition metal dichalcogenides, the reduced Coulomb screening results in strongly bound excitons which dominate linear and nonlinear optical response. Despite large number of studies, a clear understanding on how many-body correlation effects affect excitonic resonances femtosecond time scale is still lacking. Here, we use ultrashort laser pulses to measure transient response 1L-WS2. order disentangle effects, perform exciton line-shape analysis, study its temporal...
Abstract Localized states in two-dimensional (2D) transition metal dichalcogenides (TMDCs) have been the subject of intense study, driven by potential applications quantum information science. Despite rapidly growing knowledge surrounding these emitters, their microscopic nature is still not fully understood, limiting production and application. Motivated this challenge, recent theoretical experimental evidence showing that nanowrinkles generate strain-localized room-temperature we...
Manipulating the optical landscape of single quantum dots (QDs) is essential to increase emitted photon output, enhancing their performance as chemical sensors and single-photon sources. Micro-optical structures are typically used for this task, with drawback a large size compared embedded emitters. Nanophotonic architectures hold promise modify dramatically emission properties QDs, boosting light–matter interactions at nanoscale, in ultracompact devices. Here, we investigate interplay...
Abstract Single-layer transition metal dichalcogenides are at the center of an ever increasing research effort both in terms fundamental physics and applications. Exciton–phonon coupling plays a key role determining (opto)electronic properties these materials. However, exciton–phonon strength has not been measured room temperature. Here, we use two-dimensional micro-spectroscopy to determine single-layer MoSe 2 . We detect beating signals as function waiting time induced by between A...
Monolayer transition metal dichalcogenides (ML-TMDs) are two-dimensional semiconductors that stack to form heterostructures (HSs) with tailored electronic and optical properties. TMD/TMD-HSs like WS2/MoS2 have type II band alignment long-lived (nanosecond) interlayer excitons following sub-100 fs charge transfer (ICT) from the photoexcited intralayer exciton. While many studies demonstrated ultrafast nature of ICT processes, we still lack a clear physical understanding due trade-off between...
Nonlinear interactions between excitons strongly coupled to light are key for accessing quantum many-body phenomena in polariton systems. Atomically-thin two-dimensional semiconductors provide an attractive platform strong light-matter coupling owing many controllable excitonic degrees of freedom. Among these, the recently emerged exciton hybridization opens access unexplored species, with a promise enhanced interactions. Here, we employ hybridized interlayer (hIX) bilayer MoS2 achieve...
The coupling of the electron system to lattice vibrations and their time-dependent control detection provide unique insight into nonequilibrium physics semiconductors. Here, we investigate ultrafast transient response semiconducting monolayer 2H-MoTe2 encapsulated with hBN using broadband optical pump-probe microscopy. sub-40 fs pump pulse triggers extremely intense long-lived coherent oscillations in spectral region A' B' exciton resonances, up ∼20% maximum signal, due displacive excitation...
Raman microscopy is a powerful analytical technique for materials and life sciences that enables mapping the spatial distribution of chemical composition sample. State-of-the-art microscopes, based on point-scanning frequency-domain detection, have long (∼1s) pixel dwell times, making it challenging to acquire images significant area (e.g., 100×100µm). Here we present compact wide-field microscope time-domain Fourier-transform approach, which parallel acquisition spectra all pixels 2D...
Nonlinear optical processes lie at the heart of frequency tunable coherent light sources, including entangled photon sources and squeezed states light, they have become ubiquitous in fields ranging from ultrafast spectroscopy to quantum information processing. van der Waals materials recently emerged as dynamically highly nonlinear platforms with ultracompact footprints. In particular, semiconducting like transition metal dichalcogenides possess large nonlinearity, orders magnitude higher...
The equilibrium and non-equilibrium optical properties of single-layer transition metal dichalcogenides (TMDs) are determined by strongly bound excitons. Exciton relaxation dynamics in TMDs have been extensively studied time-domain spectroscopies. However, the formation excitons following non-resonant photoexcitation free electron-hole pairs challenging to directly probe because their inherently fast timescales. Here we use extremely short pulses non-resonantly excite an plasma show...
Bismuth telluride halides (BiTeX) are Rashba-type crystals with several potential applications ranging from spintronics and nonlinear optics to energy. Their layered structures low cleavage energies allow their production in a two-dimensional form, opening the path miniaturized device concepts. The possibility exfoliate bulk BiTeX liquid represents useful tool formulate large variety of functional inks for large-scale cost-effective manufacturing. Nevertheless, exfoliation BiTeI by means...
Waveguides play a key role in the implementation of on-chip optical elements and, therefore, lie at heart integrated photonics. To add functionalities layered materials to existing technologies, dedicated fabrication protocols are required. Here, we build on laser writing pattern grating structures into bulk noncentrosymmetric transition metal dichalcogenides with grooves as sharp 250 nm. Using thin flakes 3R-MoS2 that act waveguides for near-infrared light, demonstrate functionality...
Due to their strong light-matter interaction, monolayer transition metal dichalcogenides (TMDs) have proven be promising candidates for nonlinear optics and optoelectronics. Here, we characterize the absorption of chemical vapour deposition (CVD)-grown MoSe2 in 720–810 nm wavelength range. Surprisingly, despite presence exciton resonances, exhibits a uniform modulation depth ∼80 ± 3% saturation intensity ∼2.5 0.4 MW/cm2. In addition, pump-probe spectroscopy is performed confirm saturable...
We calculate the time evolution of transient reflection signal in an MoS2 monolayer on a SiO2/Si substrate using first-principles out-of-equilibrium real-time methods. Our simulations provide simple and intuitive physical picture for delayed, yet ultrafast, whose rise depends excess energy pump laser: at laser energies above A- B-exciton, pulse excites electrons holes far away from K valleys first Brillouin zone. Electron–phonon hole–phonon scattering lead to gradual relaxation carriers...
Here we present an interferometric wide field hyperspectral microscope based on a common-path birefringent interferometer with translating wedges, to measure photoluminescence emission from two-dimensional semiconductors. We show diffraction-limited microscopy materials across millimeter areas, proving that our is compact, stable and fast tool characterize the optical properties morphology of 2D ultralarge areas.