Single-cycle terahertz (THz) transients in the frequency range 0.3–7?THz with electric-field amplitudes of more than 400?kV?cm are generated by four-wave mixing fundamental and second harmonic 25?fs pulses from a Ti:sapphire amplifier ionized air. These fully characterized electro-optic sampling ZnTe GaP crystals. One can tune center THz varying length incident pulse. The amplitude increases linearly pulse energy.

We report on an intense mid-infrared light source that provides femtosecond pulses a microjoule energy level, broadly tunable in the 3–20-µm wavelength range with pulse durations as short 50 fs at 5 µm. The are generated by phase-matched difference-frequency mixing GaSe of near-infrared signal and idler parametric device based 1-kHz Ti:sapphire amplifier system. Pulse characterized different techniques including autocorrelation measurements AgGaS2, two-photon absorption InSb,...

Reversible structural changes of a nanostructure were measured nondestructively with subpicometer spatial and subpicosecond temporal resolution via x-ray diffraction (XRD). The spatially periodic femtosecond excitation gallium arsenide/aluminum arsenide superlattice results in coherent lattice motions 3.5-picosecond period, which was directly monitored by pulses at 1-kilohertz repetition rate. Small (DeltaR/R = 0.01) weak Bragg reflexes (R 0.005) detected. phase amplitude the oscillatory XRD...

We present a combined theoretical and experimental study of spatiotemporal propagation effects in terahertz (THz) generation gases using two-color ionizing laser pulses. The observed strong broadening the THz spectra with increasing gas pressure reveals prominent role reshaping plasma-induced blueshift pump pulses process. Results obtained from (3+1)-dimensional simulations are good agreement findings clarify mechanisms responsible for emission.

The nonlinear dynamics of electrons in multilayer epitaxial graphene is investigated by time-resolved terahertz (THz) spectroscopy a regime where the interaction with external field dominates over scattering processes. predominantly coherent electron response to THz involves both intra- and interband currents, leading coherently driven transitions carriers generation higher harmonics carrier frequency. overall behavior layers always absorptive, even after an initial electron-hole...

Recent experimental progress has allowed for the implementation of nonlinear two-dimensional (2D) terahertz (THz) spectroscopy in ultrafast time domain. We discuss principles this technique based on multiple phase-locked electric field transients interacting a collinear geometry with solid and phase-resolved detection THz fields after interaction sample. To illustrate potential new method, 2D correlation spectra coupled intersubband-longitudinal optical phonon excitations double quantum well...

Over more than a century, X-rays have transformed our understanding of the fundamental structure matter and been an indispensable tool for chemistry, physics, biology, materials science related fields. Recent advances in ultrafast X-ray sources operating femtosecond to attosecond regimes opened important new frontier science. These now enable: (i) sensitive probing structural dynamics on timescales atomic motion, (ii) element-specific electronic charge (iii) powerful approaches unravelling...

Electrons in bulk n-doped GaAs at a lattice temperature of 300 K are driven by ultrashort high-field transients up to kV/cm the terahertz frequency range. In lowest conduction band carriers show coherent ballistic motion, which is detected via THz field emitted them. This partial Bloch oscillation reproduced quantum-kinetic theory transport on ultrafast time scales.

The porous high surface area and conducting properties of mesoporous carbon nanoparticles, CNPs (<500 nm diameter NPs, pore dimensions ∼6.3 nm), are implemented to design electrically contacted enzyme electrodes for biosensing biofuel cell applications. relay units ferrocene methanol, Fc-MeOH, methylene blue, MB(+), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS(2-), loaded in the pores CNPs, capped with glucose oxidase, GOx, horseradish peroxidase, HRP, or bilirubin BOD,...

Optical spectra of high-transition-temperature superconductors in the mid-infrared display a gap in-plane conductivity whose role for superconductivity remains unresolved. Femtosecond measurements reflectivity YBa(2)Cu(3)O(7-delta) after nonequilibrium optical excitation are used to demonstrate ultrafast fill-in this and reveal two constituents: picosecond recovery superconducting condensate underdoped optimally doped material and, YBa(2)Cu(3)O(7-delta), an additional subpicosecond component...

Phase-matched difference-frequency mixing in a thin GaSe crystal within the broad spectrum of 25-fs pulses from Ti:sapphire oscillator multipass amplifier system permits generation few-cycle electric field transients, frequencies up to 30 THz, and amplitudes more than 1 MV/cm. The transients generated at 1-kHz repetition rate are directly measured by electro-optic sampling 12-fs probe 75-MHz repetition-rate combination with novel electronic gating technique.

Strong electric-field transients resonant to intersubband transitions in n-type modulation-doped GaAs/AlGaAs quantum wells induce coherent Rabi oscillations, which are demonstrated by a phase-resolved measurement of the light emitted sample. The time evolution polarization is influenced Coulomb-mediated many-body effects. subpicosecond period and phase oscillations controlled properties midinfrared driving pulse.

Phase-matched difference frequency mixing within the broad spectrum of single 13 fs pulses from a cavity-dumped, mode-locked Ti:sapphire laser in GaSe crystal allows generation femtosecond mid-infrared pulses, continuously tunable wavelength range 7 to 20 μm. Pulse durations down 95 at 9.3 μm are directly measured. Model calculations including full dispersion show that chirp pump change both pulse duration and conversion efficiency obtained nonlinear process, agreement with experiment.

We report the first analysis of polarization and lattice dynamics in a metal/ferroelectric/metal nanolayer system by femtosecond x-ray diffraction. Two Bragg reflections provide information on coupled two relevant phonon modes for ferroelectricity perovskites, tetragonal distortion soft mode. Optical excitation ${\mathrm{SrRuO}}_{3}$ metal layers generates giant stress ($>1\text{ }\text{ }\mathrm{GPa}$) compressing ${\mathrm{PbZr}}_{0.2}{\mathrm{Ti}}_{0.8}{\mathrm{O}}_{3}$ up to 2%. The...

Excitation of an n-type GaAs layer by intense ultrashort terahertz pulses causes coherent emission at 2 THz. Phase-resolved nonlinear propagation experiments show a picosecond decay the emitted field, despite ultrafast carrier-carrier scattering sample temperature 300 K. While linear THz response is in agreement with Drude free electrons, dominated super-radiant optically inverted impurity transitions. A quantum mechanical discrete state model using potential disordered impurities accounts...

A tunable regenerative Ti:sapphire amplifier system working at a 1-kHz repetition rate pumps an optical parametric generator providing near-infrared pulses in the wavelength range from 1 to 2.5 μm. The signal and idler with duration below 100 fs are mixed AgGaS2 crystal generate difference frequency. midinfrared output is continuously between 3.3 10 μm, pulse energies of as high 50 nJ durations 160 fs, directly determined cross-correlation measurements.

We present a viewpoint of the transport process in quantum cascade laser structures which spatial charge through structure is property coherent quantum-mechanical wavefunctions. In contrast, scattering processes redistribute particles energy and momentum but do not directly cause motion charge.

We present a novel approach for femtosecond two-dimensional (2D) spectroscopy in the midinfrared combining collinear beam geometry and phase-resolved detection. Two phase-locked pulses of variable time delay tau interact with sample. The transmitted electric fields are measured real t by electro-optic sampling. 2D spectra generated Fourier transforming signal along two axes t. In spectra, nonlinear signals originating from different orders n field separated. Such decomposition overall...

We discuss a novel approach for nonlinear two-dimensional (2D) spectroscopy in the terahertz (THz) frequency range which is based on collinear interaction geometry of sequence THz pulses with sample. The polarization determined by phase-resolved measurement electric field transmitted through sample as function delay τ between two phase-locked and "real" time t. information provided single 2D scan along t axes equivalent to that from noncollinear photon-echo setup equipped four local...

The terahertz (THz) response of the ferroelectric prototype material lithium niobate (LiNbO3) is studied in nonperturbative regime light-matter interaction. Applying two-dimensional THz spectroscopy with few-cycle pulses an amplitude E≈100 kV/cm and a center frequency 2 THz, we dissect overall nonlinear into different orders electric field. underlying current interband character consists strong low-frequency shift (SC) higher harmonics fundamental. SC component originates from lack inversion...

We report the kinematic and early clinical results of a patient- observer-blinded randomised controlled trial in which CT scans were used to compare potential impingement-free range movement (ROM) acetabular component cover between patients treated with either navigated 'femur-first' total hip arthroplasty (THA) method (n = 66; male/female 29/37, mean age 62.5 years; 50 74) or conventional THA 69; 35/34, 62.9 75). The Hip Osteoarthritis Outcome Score, Harris score, Euro-Qol-5D Mancuso...

Ultrashort soft and hard x-ray pulses are sensitive probes of structural dynamics on the picometer length femtosecond time scales electronic atomic motions. Recent progress in generating such has initiated new directions condensed matter research, exploiting a variety absorption, scattering, diffraction methods to probe photoinduced dynamics. Atomic motion, changes local structure long-range order, as well correlated electron motion charge transfer have been resolved space time, providing...