We describe a powerful imaging modality for terahertz (THz) radiation, THz wide aperture reflection tomography (WART). Edge maps of an object's cross section are reconstructed from a series of time-domain reflection measurements at different viewing angles. Each measurement corresponds to a parallel line projection of the object's cross section. The filtered backprojection algorithm is applied ...

We propose and investigate in detail a novel tunable, compact, room temperature terahertz (THz) emitter using individual microdisk resonators for both optical and THz waves with the capability of radiating THz field in 0.5–10 THz range with tuning frequency resolution of 0.05 THz. Enhanced THz generation is achieved by employing a nonlinear optical disk resonator with a high value of second-ord...

We present an optical parametric oscillator pumped by a single mode Q-switched nanosecond Nd:YVO(4) laser for terahertz generation in periodically poled lithium niobate with a new phase matching scheme. This new method leads to an emission of terahertz radiation close to the Cherenkov angle and to a parallel propagation of the pump and signal wave. The emission frequency of this novel source is...

We report a high efficiency, broadband terahertz (THz) modulator following a study of phthalocyanine-compound organic films irradiated with an external excitation laser. Both transmission and reflection modulations of each organic/silicon bilayers were measured using THz time-domain and continuous-wave systems. For very low intensities, the experimental results show that AlClPc/Si can achieve a...

Natural cork enclosures, due to their cell structure, composition, and low moisture are fairly transparent to terahertz (THz) and millimeter waves enabling nondestructive evaluation of the cork's surface and interior. It is shown that the attenuation coefficient of the defect-free cork can be modeled with a Mie scattering model in the weakly scattering limit. Contrast in the THz images is a res...

Gate-controllable transmission of terahertz (THz) radiation makes graphene a promising material for making high-speed THz wave modulators. However, to date, graphene-based THz modulators have exhibited only small on/off ratios due to small THz absorption in single-layer graphene. Here we demonstrate a ∼50% amplitude modulation of THz waves with gated single-layer graphene by the use of extraord...

We present the redesign and improved performance of the laser terahertz emission microscope (LTEM), which is a potential tool for locating electrical failures in integrated circuits. The LTEM produces an image of the THz waves emitted when the circuit is irradiated by a femtosecond laser; the amplitude of the THz emission is proportional to the local electric field. By redesigning the optical s...

We experimentally demonstrate ultrafast polarization switching of terahertz (THz) radiation generated by dual-color driving pulses composed of orthogonally polarized fundamental and second-harmonic waves, which can be controlled by field-free molecular alignment in air by modulating the relative phase between the two field components as a transient dynamic wave plate. By fine-tuning the time de...

Recent progress in analytical terahertz (THz) spectroscopy is reviewed with illustrative examples showing that it is an effective method for detecting and identifying intermolecular interactions in chemical compounds, such as hydrogen bonds. The unique and characteristic properties of THz waves, their significance to both science and industry, and the bases of one of the successful fields of an...

Terahertz (THz; 10(12) Hz) waves have a frequency from 0.1 to 10 THz between the visible light and microwave domains. THz waves are expected to be useful for analysis of the histological features, without any staining procedure that is an indispensable prerequisite for optical microscopy. It has been demonstrated that THz transmittances at cancer and normal tissues are different. However, spect...