We propose and demonstrate a terahertz (THz) time-domain spectroscopy combined with ellipsometry. The complex optical constants of Si wafer low resistivity are deduced from the measurements wave forms reflected s- p-polarized THz pulses without reference measurement. obtained dispersion refractive index above ∼0.2 shows good agreement that predicted by Drude theory. ellipsometry in low-frequency region strongly affected slight error ellipsometric angle originating mainly misalignment...

Spectroscopies using terahertz (THz) radiation excited by ultrashort laser pulses have been rapidly developing recently. In this paper, the principles of various types THz time domain spectroscopies (THz TDSs), i.e. transmission-, reflection-and ellipsometry-type TDSs, and their applications to characterization semiconductors are described. addition TDS a femtosecond laser, sub-THz system cheap compact continuous multimode diode is also

We report on the observation of terahertz (THz) radiation emitted from antiferromagnetic (AFM) single-crystal nickel oxide irradiated with femtosecond laser pulses. Periodic oscillations observed in THz waveforms are assigned to coherent AFM magnons excited by Impulsive stimulated Raman scattering process is a possible mechanism magnon excitation The NiO generate waves magnetic dipole radiation, which inverse resonance absorption waves.

We present a reflection-type terahertz time-domain spectroscopic ellipsometry (THz-TDSE) technique for measuring the complex dielectric constants of thin-film materials without replacement sample. THz-TDSE provides from ratio amplitude reflection coefficients between p- and s-polarized THz waves. The measured doped GaAs thin films show good agreement with predictions Drude model, even though film thickness is order tenth penetration depth In addition, we demonstrate measurements soft-phonon...

Abstract Terahertz pulses trapped as surface waves on a wire waveguide can be flexibly transmitted and focused to sub-wavelength dimensions by using, for example, tapered tip. This is particularly useful applications that require high-field pulses. However, the generation of strong terahertz remains challenge. Here, ultrafast field propagation along metal driven femtosecond laser pulse with an intensity 10 18 W/cm 2 characterized electron deflectometry. From experimental numerical results,...

Terahertz (THz) emission from argon cluster plasma, generated by intense femtosecond laser pulses in the energy range of 10–70 mJ, has been investigated. THz polarization, dependence, and angular distribution were measured to provide an initial discussion on mechanisms emission. much higher clusters than gas, which indicates that plasma produced atomic holds considerable promise as source.

We investigated terahertz (THz) radiation from twinned NiO(110) single crystals excited by optical laser pulses with various polarization states. found that the polarity of THz optically coherent antiferromagnetic (AFM) magnons can be controlled switching helicity circular and rotating direction linear pulses. The dependence on suggests AFM are inverse Faraday effect in a crystal magnetic birefringence.

Interesting polarization characteristics of two-dimensional metallic photonic crystals (2D-MPC) in the subterahertz region have been found. We measured temporal wave form THz transmitted thorough 2D-MPC using a time domain spectroscopic system. The linear incident through becomes elliptical with slight tilting angle from normal incidence. This result indicates that behaves not only as band-pass filter already reported, but also plate. large change is attributed to strong TE–TM mixing 2D-MPC.

The characteristics of THz pulse radiation from argon clusters irradiated with intense femtosecond laser pulses have been investigated. average power the radiated is approximately 40 times greater than that gas. enhancement originates large absorption by clusters. polarization state and angular distribution show no dependence on polarization, which suggests laser-induced charge separation along propagation direction.

Terahertz (THz) radiation from atomic clusters illuminated by intense femtosecond laser pulses is investigated. By studying the angular distribution, polarization properties and energy dependence of THz waves, we aim to obtain a proper understanding mechanism generation. The waves measured in this study differ those predicted previously proposed mechanisms. To interpret these qualitatively, propose that generated time-varying quadrupoles, which are produced ponderomotive force pulse.

Simultaneous emission of the THz wave and hard X-ray from thin water free-flow was induced by irradiation tightly-focused femtosecond laser pulses (35 fs, 800 nm, 500 Hz) in air. Intensity measurements were carried out at same time with time-domain spectroscopy (TDS) based on electro-optic sampling a ZnTe(110) crystal Geiger counter, respectively. profiles as function solution flow position along incident axis focus show that profile width is broader than X-ray. Furthermore, measured...

Abstract Intense THz sources are expected for further progresses in nonlinear science and technology. Liquids like water durable continuously-reusable under intense laser irradiation emission though such studies on from targets so far limited. Polarisation fine control of is demonstrated with a tilted micro-thin flow by the two cross-linearly-polarised femtosecond pulses (800nm, 35fs, transform-limited) spatio-temporal offsets. With an optimized horizontal offset at ∼11 μm between ∼8 focal...

We have measured the soft-mode dispersion of SrTiO3 bulk single crystals by terahertz time-domain spectroscopic ellipsometry (THz-TDSE). The real and imaginary parts dielectric function sample are independently derived from complex amplitude reflectivities p- s-polarized pulses. TO1 resonance is clearly observed at 2.62 THz (87 cm-1). spectra agree well with those predicted using general harmonic oscillator model parameters obtained conventional Fourier-transform far-infrared (FT-FIR)...

It has been demonstrated that the interaction between argon clusters and intense femtosecond double laser pulses with appropriate intervals in time space provides important properties for terahertz electromagnetic wave generation, namely, high forward directivity, power enhancement, linear polarization a variable direction. Irradiating (1 3 mJ, 40 fs, 810 nm) 133-ps 40-μm results emission direction is 10 times greater than single pulse. The of waves can be varied by changing relative focal...

THz emission in air under the irradiation of a pair tightly-focused femtosecond laser pulses (800nm, 35fs) with nanosecond time delay and micro-meter spatial offsets is studied polarization-sensitive time-domain spectroscopy time-resolved imaging. The pre-pulse induces air-breakdown at its focus, which results expansion shockwave front traveling outward. When main pulse irradiates such far from focus delay, intensity was enhanced up to ∼13-times linear polarization aligned along line between...

Free-carrier Faraday ellipticity and rotation are measured for a moderately doped n-type silicon wafer with the resistivity of 1.1Ωcm under magnetic fields ±3T using terahertz time-domain spectroscopy. From experimental data, we obtain time evolution electric-field vector radiation pulses. When field is applied to sample, transmitted has an elliptic polarization its major axis rotated from direction incident (Faraday effect). The angle obtained directly pulse (first pulse) reflected twice at...

Emission of THz radiation from air breakdown at focused ultra-short fs-laser pulses (800 nm/35 fs) was investigated for the 3D spatio-temporal control where two pre-pulses are used before main-pulse.The laser pulse induced forms a ∼ 120 m-long focal volume generate shockwaves which deliver denser into region main enhanced generation 0.1-2.5 spectral window.The intensity pre-and main-pulses tunnelling ionisation intensities (1 -3) × 10 16 W/cm 2 and corresponded to sub-critical (transparent)...

Terahertz (THz) radiation from antiferromagnetic (AFM) MnO excited by femtosecond laser pulses has been investigated. The radiated THz pulse consists of a single-cycle broadband and an oscillating component with frequency 0.83 at 10 K. oscillations are magnetic dipole optically AFM magnons. We found that the peak amplitude increases as temperature decreases is significantly enhanced below order temperature. origin observed can be attributed to second-order nonlinear optical effects depending...

We found the irradiation of focused linearly polarized terahertz (THz)-waves emitted from THz free-electron laser (THz-FEL) engraved fine periodic stripe structures on surfaces single-crystal Si wafers. The experiments were performed at several wavelengths ranging 50 to 82 μm with a macro-pulse fluence up 32 J/cm2. are considered equivalent laser-induced surface (LIPSS) produced by femtosecond (fs)-pulsed in near-infrared (NIR) region. However, minimum period ∼1/25 wavelength present case...

Simultaneous measurements of THz wave and hard X-ray emission from thin flat water flow when irradiated by double femtosecond laser pulses (800 nm, 35 fs/transform-limited, 0.5 kHz, delay times up to 15 ns) were carried out. time-domain spectroscopy detection Geiger counters performed at the transmission reflection sides flow. spectra show their dynamic peak shifts toward low frequency with highest intensity enhancements more than 1.5 × 10 3 in |E| 2 accumulated over whole spectrum range 0–3...

Metamaterials with metallic wire-gird structures support extremely low frequency plasmons and their electromagnetic responses exhibit characteristics described by the Drude model. In this paper, we have investigated of wire-grid in terahertz range when periodic random cuts are introduced wires. It is found experimentally that a transition from response negative permittivity to an insulators-like large positive at frequencies small also revealed finite-difference time-domain simulation such...

We have developed a terahertz time-domain magneto-optical ellipsometry to deduce the effective mass, scattering time, density, and type (n or p) of free carriers independently. The parameters are derived from diagonal off-diagonal components complex dielectric tensor obtained by measurements Kerr effects under magnetic field 0.46 T using generalized Drude model. derivation these for n-type InAs wafers with different carrier densities is demonstrated. density dependence mass agrees well...