We systematically investigate the excitonic dephasing of three representative transition-metal dichalcogenides, namely, ${\mathrm{MoS}}_{2}$, ${\mathrm{MoSe}}_{2}$, and ${\mathrm{WSe}}_{2}$ atomic monolayer thick bulk crystals, in order to gain a proper understanding factors that determine optical coherence these materials. Coherent nonlinear spectroscopy temperature dependent absorption, combined with theoretical calculations phonon spectra, indicate electron-phonon interactions, be...

Nonlinear two-dimensional Fourier transform (2DFT) and linear absorption spectroscopy are used to study the electronic structure optical properties of excitons in layered semiconductor GaSe. At 1s exciton resonance, two peaks identified spectra, which assigned splitting ground state into triplet singlet states. 2DFT spectra acquired for co-linear polarization excitation pulses feature an additional peak originating from coherent energy transfer between triplet. cross-linear pulses, expose a...

High yield syntheses of size-confined Bi2Te3 and Sb2Te3 nanocrystals nanoflakes, their alloys, were carried out by a facile glycol-mediated solvothermal process. Phase purity good crystalline quality achieved for all alloy compositions this synthesis The isotropically anisotropically shaped obtained without using any capping molecule, template, or ligand. Plausible growth mechanisms have been proposed. Densification via spark plasma sintering allowed dense bulk polycrystalline specimens with...

The dephasing and lifetime of excitons in InSe layered crystals are carefully measured using three-pulse, four-wave mixing two-dimensional Fourier transform (2DFT) spectroscopy. We obtain a detailed picture the mechanism excitonic this material. 2DFT spectra reveal contributions from coherent excitation continuum states, whereas temperature dependence provides description phonon-exciton interactions low limit homogeneous linewidth. density reveals excitation-induced due to exciton-exciton...

Abstract We present time-integrated four-wave mixing measurements on monolayer MoSe 2 in magnetic fields up to 25 T. The experimental data together with time-dependent density function theory calculations provide interesting insights into the biexciton formation and dynamics. In presence of coherence at negative positive time delays is dominated by intervalley biexcitons. demonstrate that can serve as a control enhance help search for more exotic states matter, including creation multiple...

We apply Linear Prediction from Singular Value Decomposition (LPSVD) to two-dimensional complex optical data in the time-domain generate spectra with advantages over discrete Fourier transformation (DFT). LPSVD is a non-iterative procedure that fits sum of damped sinusoids, or Lorentzian peaks spectral domain. Because fitting linear, it not necessary give initial guess parameters as nonlinear fits. Although one-dimensional algorithm, can be performed column-wise on data. The method has been...

In modulation doped quantum wells, the excitons are formed as a result of interactions charged holes with electrons at Fermi edge in conduction band, leading to so-called ``Mahan excitons.'' The binding energy Mahan is expected be greatly reduced and any coherence destroyed screening electron-electron interactions. Surprisingly, we observe strong between heavy hole light excitons. Such correlations revealed by dominating cross-diagonal peaks both one-quantum two-quantum two-dimensional...

The dephasing of PbS quantum dots has been carefully measured using three pulse four-wave mixing and two-dimensional nonlinear optical spectroscopy. temperature dependence the homogeneous linewidth obtained from spectra indicates significant scattering by acoustic phonons, whereas excitation density shows negligible induced broadening in agreement with previous results. rapid is attributed to elastic phonons. However, two components emerge, short component that dominates decay a weaker...

Extract Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Florida, USA, August 5 – 9,

A multidimensional optical nonlinear spectrometer (MONSTR) is a robust, ultrastable platform consisting of nested and folded Michelson interferometers that can be actively phase stabilized. The MONSTR provides output pulses for excitation materials phase-stabilized reference heterodyne detection the induced signal. This generates square identical laser adjusted to have arbitrary time delays between them while maintaining stability. arrangement ideal performing coherent experiments, such as...

Transparent conductive oxides such as indium tin oxide (ITO) bear the potential to deliver efficient all-optical functionality due their record-breaking optical nonlinearity at epsilon near zero (ENZ) wavelengths. All-optical applications generally involve more than one beam, but, our knowledge, coherent interaction between beams has not previously been discussed in these materials, which have a hot electron nonlinearity. Here we study ENZ ITO and show that spatial temporal interference...

Cooperative effects allow for fascinating characteristics in light-matter interacting systems. Here, we study naturally occurring superradiant coupling a class of quasi-two-dimensional, layered semiconductor We perform optical absorption experiments the lowest exciton transition-metal dichalcogenides with different numbers atomic layers. examine two representative materials, MoSe$_2$ and WSe$_2$, using incoherent broadband white light. The measured transmission at A resonance does not...

Multidimensional coherent spectroscopy (MDCS) is used to separate and incoherent many-body contributions the population-time dynamics in a GaAs-based semiconductor microcavity encapsulating single InGaAs quantum well. In three-pulse four-wave-mixing scheme, second delay time population that MDCS probes excited-state coherences dynamics. Nonlinear optical interactions can mix these contributions, which are isolated here for lower- upper-exciton-polariton through self- mutual-interaction...

An experimental apparatus is described for multidimensional optical spectroscopy with fully automated polarization control, based on liquid crystal variable retarders. Polarization dependence of rephasing two-dimensional coherent spectra are measured in a single scan, absolute phasing performed all configurations through auxiliary measurement at the beginning scan. A factor three improvement acquisition time demonstrated, compared to without control. Results presented GaAs quantum well...

We have performed two-dimensional Fourier transform spectroscopy on intrinsic and modulation doped quantum wells in external magnetic fields up to 10 T. In the undoped sample, strong Coulomb interactions increasing separations of electron hole charge distributions with lead a nontrivial in-plane dispersion magneto-excitons. Thus, discrete degenerate Landau levels are coupled continuum. The signature this continuum is emergence elongated spectral line shapes at level energies, which exposed...

The dephasing of the Fermi edge singularity excitations in two modulation doped single quantum wells 12 nm and 18 thickness in-well carrier concentration ∼4 × 10(11) cm(-2) was carefully measured using spectrally resolved four-wave mixing (FWM) two-dimensional Fourier transform (2DFT) spectroscopy. Although absorption at is broad this doping level, FWM shows narrow resonances. Two peaks are observed separated by heavy hole/light hole energy splitting. Temperature dependent "rephasing" (S1)...

Peak amplitude, phase, linewidth, and energy are recorded for exciton-polaritons measured with rephasing two-dimensional coherent spectroscopy as a function of detuning polarization. The relative phases respect to co-circular polarization dependent.

We investigate the excitonic dephasing of transition metal dichalcogenides, namely MoS2, MoSe2 and WSe2 atomic monolayer thick bulk crystals, in order to understand factors that determine optical coherence these materials. Coherent nonlinear spectroscopy, temperature dependent absorption combined with theoretical calculations phonon spectra, reveal important role electron-phonon interactions plat process. The dependence electronic band gap linewidth 'ab initio' energies density state strong...

We performed nonlinear optical two-dimensional Fourier transform spectroscopy measurements using an resistive high-field magnet on GaAs quantum wells. Magnetic fields up to 25 T can be achieved the split helix magnet. Two-dimensional based coherent four-wave mixing signal require phase stability. Therefore, these are difficult perform in environments prone mechanical vibrations. Large magnets use extensive quantities of cooling water, which causes vibrations, making very challenging. Here,...

We perform two-dimensional Fourier transform spectroscopy on magneto-excitons in GaAs at magnetic fields and observe Zeeman splitting of the excitons. The components are clearly resolved as separate peaks due to nature spectra, leading a more accurate measurement Landé g factors. Quantum coherent coupling between is observed using polarization dependent one-quantum spectroscopy. use two-quantum investigate higher four-particle correlations high reveal role transitions. experimental spectra...