A method for obtaining the average refractive indexes of a birefringent material in the terahertz region in a single measurement with a standard terahertz time-domain spectrometer is presented. The method is based on processing the frequency-domain interference between terahertz pulses and echoes through the Fourier transform of the terahertz spectrum. The technique also allows the determinatio...

By applying a helical electric field along a plasma region, a revolving electron current is formed along the plasma and an elliptically polarized far-field terahertz wave pattern is observed. The observed terahertz wave polarization reveals the remarkable role of velocity retardation between optical pulses and generated terahertz pulses in the generation process. Extensive simulations, includin...

Articles you may be interested in InAs/AlSb widely tunable external cavity quantum cascade laser around 3.2 μm Room temperature single-mode terahertz sources based on intracavity difference-frequency generation in quantum cascade lasers Appl. Terahertz sources based on intracavity frequency mixing in mid-infrared quantum cascade lasers with passive nonlinear sections Appl. Surface-emitting tera...

We report an experimental study of femtosecond optically excited emission of terahertz frequency electromagnetic radiation from GaxIn1−xAs bulk crystals with alloy composition in the range between 0 x 0.65. The terahertz-emission mechanisms in bulk GaxIn1−xAs were studied as a function of carrier mobility, carrier concentrations, band gap as well as polycrystal grain size. Our experiments and a...

Controlling the propagation properties of terahertz waves is very important in terahertz technologies applied in high-speed communication. Therefore a new-type optically tuned terahertz modulator based on multilayer-MoS2 and silicon is experimentally demonstrated. The terahertz transmission could be significantly modulated by changing the power of the pumping laser. With an annealing treatment ...

We investigate the self-phase modulation (SPM) of a single-cycle terahertz pulse in a semiconductor, using bulk n-GaAs as a model system. The SPM arises from the heating of free electrons in the electric field of the terahertz pulse, leading to an ultrafast reduction of the plasma frequency, and hence to a strong modification of the terahertz-range dielectric function of the material. Terahertz...

Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors as security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the sou...

Semi-metals might offer a stronger interaction and a better confinement for terahertz wave than semiconductors, while preserve tunability. Particularly, graphene-based materials are envisioned as terahertz modulators, filters and ultra-broadband sources. However, the understanding of terahertz generation from those materials is still not clear, thus limits us recognizing the potential and impro...

Articles you may be interested in Distributed feedback terahertz frequency quantum cascade lasers with dual periodicity gratings Appl. Narrow-band injection seeding of a terahertz frequency quantum cascade laser: Selection and suppression of longitudinal modes Appl. High order sideband generation in terahertz quantum cascade lasers Appl. High frequency modulation of mid-infrared quantum cascade...

We experimentally demonstrate a chiral metamaterial exhibiting negative refractive index at terahertz frequencies. The presence of strong chirality in the terahertz metamaterial lifts the degeneracy for the two circularly polarized waves and allows for the achievement of negative refractive index without requiring simultaneously negative permittivity and negative permeability. The realization o...