Low-frequency currents induced by ultrashort laser-driven ionization can emit extremely broadband, single-cycle terahertz pulses. We present a model that predicts strong wavelength dependence of the THz emission in good agreement with our experimental study. This reveals combined effects plasma rising proportionally to square pump and wavelength-dependent focusing conditions lead 30 times higher at 1800 nm compared an 800 wavelength. Unrivaled electric field strengths 4.4 MV/cm are achieved...

A Faraday isolator is an electromagnetic non-reciprocal device, a key element in photonics. It required to shield sources against the effect of back-reflected light, as well limit detrimental back-propagating spontaneous emissions. common variant, circulator, widely used obtain complete separation between forward- and backward-propagating waves, thus enabling realization desired transfer function reflection only. Here we demonstrate terahertz isolator, operating on bandwidth exceeding one...

The fundamental properties of water molecules, such as their molecular polarizability, have not yet been clarified. hydrogen bond network is generally considered to play an important role in the thermodynamic water. terahertz (THz) Kerr effect technique, a novel tool, expected be useful exploring low-frequency dynamics liquid Here, we use intense and ultrabroadband THz pulse (peak electric field strength 14.9 MV/cm, centre frequency 3.9 THz, bandwidth 1-10 THz) resonantly excite...

We report on efficient THz generation in DAST by optical rectification of intense mid-IR pulses centered at (i) 3.9 μm and (ii) its second harmonic 1.95 μm. Suppression multi-photon absorption shifts the onset saturation conversion efficiency to pump energy densities, which are almost an order magnitude higher as compared conventional schemes 1.5 Despite strong linear μm, exhibits a high optical-to-THz efficiency, we attribute resonantly enhanced nonlinearity advantageous phase matching...

We demonstrate efficient optical rectification in the organic crystal BNA (N-benzyl-2-methyl-4-nitroaniline), driven by a temporally compressed, commercially available industrial Yb-laser system operating at 540 kHz repetition rate. Our terahertz (THz) source reaches 5.6 mW of THz average power 4.7 W, 45 fs pulses, and resulting THz-time domain spectroscopy combines very broad bandwidth 7.5 high dynamic range 75 dB (in measurement time 70 s). The conversion efficiency maximum is 0.12%. To...

The distinctive ability of nanometallic structures to manipulate light at the nanoscale has recently promoted their use for a spectacular set applications in wide range areas research including artificial optical materials, nano-imaging, biosensing, and nonlinear optics.Here we transfer this concept terahertz spectral region, demonstrating metal nanostructure shape dipole nanoantenna, which can efficiently resonate frequencies, showing an effective cross section >100 times larger than its...

We report on the demonstration of a high figure merit (FOM) Faraday rotation in liquid terahertz (THz) regime. Using ferrofluid, broadband (11 mrad/mm) is experimentally demonstrated frequency range 0.2–0.9 THz at room temperature. Given low absorption liquid, magneto-optical (5-16 rad.cm/T) obtained.

We experimentally and numerically investigate the transmission of THz radiation through uniform nanoslit arrays. These structures are capable inducing plasmon-mediated field enhancement while concurrently providing high transmission. Combined with intense radiation, estimated strengths as 26 MV/cm obtained in near-field regime which will facilitate nonlinear experiments.

We demonstrate a 13.3 MHz repetition rate, broadband THz source with milliwatt- average power, obtained by collinear optical rectification of high-power Yb-doped thin-disk laser in the organic crystal BNA (N-benzyl-2-methyl-4-nitroaniline). Our reaches maximum power 0.95 mW an optical-to-THz efficiency 4×10-4 and spectral bandwidth spanning up to 6 at -50 dB, driven 2.4 W (after chopper duty cycle 10%), 85 fs-pulses. This high excitation was possible without damaging using diamond-heatsinked...

We investigate numerically the excitation of nonlinear magnetic interactions in a ferrite material by an energetic pump pulse terahertz (THz) radiation. The calculations are performed solving coupled Maxwell and Landau-Lifshitz-Gilbert differential equations. In time-resolved THz pump/THz probe scheme, it is demonstrated that Faraday rotation delayed can be used to map these interactions. Our study motivated ability soft x-ray free electron lasers perform imaging magnetization process at...

Charge transfer across the interface and interlayer coupling in graphene van der Waals heterostructure, which is constructed by semiconducting transition metal dichalcogenides (TMDCs), critical for their electronic optoelectronic applications. Photo-induced charge injection from TMDC to has been studied several heterostructure photodetectors. However, response time significantly varies among different reports, ranging microseconds milliseconds. In this work, using a graphene/WSe2 as an...

Generation of terahertz radiation by optical rectification intense near-infrared laser pulses in N-benzyl-2-methyl-4-nitroaniline (BNA) is investigated detail carrying out a complete characterization the radiation. We studied scaling THz yield with pump pulse repetition rate and fluence which enabled us to predict optimal operating conditions for BNA crystals at room temperature 800 nm wavelength. Furthermore, recording transmitted spectrum allowed calculate nonlinear refractive index nm.

Theoretical investigation is carried out for understanding the properties of three-dimensional electron-acoustic waves propagating in magnetized plasma whose constituents are cold electron fluid, hot electrons obeying nonthermal distribution, and stationary ions. For this purpose, hydrodynamic equations density Poisson equation used to derive corresponding nonlinear evolution equation, Zkharov–Kuznetsov (ZK) small- but finite- amplitude regime. The ZK solved analytically it found that...

We present a study of novel coupling scheme based on the use two traditional single-gap split ring resonators (SRRs) and asymmetric double-gap (ASRs) that have different spatial arrangements. Each unit cell consists resonator elements. In particular, two-SRR two-ASR cells are arranged in vertical, horizontal, diagonal configurations to form terahertz (THz) macrocell large metamaterial (MTM) array. Surprisingly, our results show arrangement both types exhibits strong resonance enhancement,...

We investigate the nonlinear wave-mixing in gases between intense, short optical pulses and long-wavelength fields (mid infrared terahertz). show numerically that beating sum- difference-frequency generation components can be isolated spectrogram of interaction, used to sample electric field oscillations pulses. This, turn, could employed as a possible characterization method provides information on real amplitude. Our numerical model is supported by spectrally resolved measurements...

VO$_{2}$ is a model material system which exhibits metal to insulator transition at 67$^\circ$C. This holds potential for future ultrafast switching in memory devices, but typically requires purely electronic process avoid the slow lattice response. The role of vibrations thus important, it not well understood and has been long-standing source controversy. We use combination spectroscopy ab initio quantum calculations unveil mechanism responsible transition. identify an atypical Peierls...

We report on terahertz (THz) generation from organic crystal N-benzyl-2-methyl-4-nitroaniline using a 1.15–1.55 μm near infrared pump. observed very large emission spectrum extending up to 7 THz, compared 2.5 THz Ti:Sa pump in previous reports. The maximum optical-to-THz conversion efficiency our experiment was 0.8% at repetition rate of 1 kHz and without saturation, leading peak electric field GV/m. Our results show pronounced phase matching privilege for intense the 1.15–1.25 range where...

Abstract Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique near-field imaging directly at source plane. A thin layer (<100 nm-thickness) photo carriers is induced on surface generation crystal, which acts...

FA:K+ and FA:Na+ color centers at the low coordination (100) (110) surface sites of AgCl AgBr thin films play important roles in providing tunable laser oscillation image sensitization. Double-well potentials these are investigated using ab initio molecular electronic structure calculations. Quantum clusters were embedded simulated Coulomb fields that closely approximate Madelung host surfaces, ions nearest neighbors to FA defect site allowed relax equilibrium. The calculated Stokes shifted...

Laser-induced ionization is a fundamental tool for the frequency conversion of lasers into spectral regions so far inaccessible, including both extreme ultraviolet and terahertz. The low-frequency currents induced by laser-driven generate extremely broadband, single-cycle terahertz pulses, with applications ranging from remote sensing to optical pulse diagnostic, yet strong limitations arise low efficiencies this mechanism. We show remarkable increase radiated energy laser wavelength we...

In past decades, ultrafast spin dynamics in magnetic systems have been associated with heat deposition from high energy laser pulses, limiting the selective access to order. Here, we use a long wavelength terahertz (THz) pump–optical probe setup measure structural features time scale. We find that complete demagnetization is possible <6 THz pulses. This occurs concurrently longitudinal acoustic phonons and an electronic response.

Abstract We employed N-benzyl-2-methyl-4-nitroaniline (BNA) crystals bonded on substrates of different thermal conductivity to generate THz radiation by pumping with 800 nm laser pulses. Crystals sapphire substrate provided four times more yield than glass substrate. A pyrodetector and a single-shot electro-optic (EO) diagnostic were for measuring the energy temporal characterisation pulse. Systematic studies carried out selection suitable EO crystal, which allowed accurate determination...

We present the results of experimental investigations terahertz radiation generation conversion efficiency in an OH1 nonlinear organic crystal pumped by femtosecond laser pulses at 1240 nm wavelength. An influence thickness on optical rectification method was studied. It is shown that optimal for maximum 1 mm, which agrees with previously made theoretical estimates.