Room temperature, broadly tunable, electrically pumped semiconductor sources in the terahertz spectral range, similar in operation simplicity to diode lasers, are highly desired for applications. An emerging technology in this area are sources based on intracavity difference-frequency generation in dual-wavelength mid-infrared quantum cascade lasers. Here we report terahertz quantum cascade las...

An unusual concept for a simple and inexpensive terahertz source is presented: unpeeling adhesive tape. The observed spectrum of this terahertz radiation exhibits a peak at 2 THz and a broader peak at 18 THz. The radiation is not polarized. The mechanism of terahertz radiation is tribocharging of the adhesive tape and subsequent discharge, possibly bremsstrahlung with absorption or energy densi...

Spatially resolved soil parameters are some of the most important pieces of information for precision agriculture. These parameters, especially the particle size distribution (texture), are costly to measure by conventional laboratory methods, and thus, in situ assessment has become the focus of a new discipline called proximal soil sensing. Terahertz (THz) radiation is a promising method for n...

We report on terahertz (THz) measurements with graphene field-effect transistors with integrated antennas (Tera-FETs) and lay special emphasis on thermoelectric contributions to the detected THz photoresponse. Graphene Tera-FETs with integrated broad-band bowtie antennas were fabricated in a CVD-based growth process and were successfully applied for detection at 600 GHz with optical NEPs down t...

We present 2D terahertz-terahertz-Raman (2D TTR) spectroscopy, the first technique, to our knowledge, to interrogate a liquid with multiple pulses of terahertz (THz) light. This hybrid approach isolates nonlinear signatures in isotropic media, and is sensitive to the coupling and anharmonicity of thermally activated THz modes that play a central role in liquid-phase chemistry. Specifically, by ...

We report a high-directivity plasmon-resonant terahertz (THz) emitter (PRE) incorporating a 3D-integrated antenna complex. The emitter structure is based on a high electron mobility transistor having unique doubly interdigitated grating gates as a broadband THz antenna that can convert non-radiative plasmons to radiative electromagnetic waves. Due to the sub-wavelength aperture of practical gra...

The terahertz (THz) part of the electromagnetic spectrum falls between the lower frequency millimetre wave region and, at higher frequencies, the far-infrared region. The frequency range extends from 0.1 THz to 10 THz, where both these limits are rather loose. As the THz region separates the more established domains of microwaves and optics, a typical THz technique will incorporate as pects of ...

Terahertz dual frequency comb spectroscopy (THz-DFCS) yields high spectral resolution without compromising bandwidth. Nonetheless, the resolution of THz-DFCS is usually limited by the laser repetition rate, which is typically between 80 MHz and 1 GHz. In this paper, we demonstrate a new method to achieve sub-repetition rate resolution in THz-DFCS by adaptively modifying the effective laser repe...

Real-time, continuous-wave terahertz imaging is demonstrated with a 10 mW, 2.52 THz (118.8 microm) far-infrared gas laser and a 160 x 120 element microbolometer camera. The microbolometer camera is designed for wavelengths of 7.5-14 microm but retains sensitivity at terahertz (THz) frequencies. The setup has no moving parts, and transmission-mode THz images can be obtained at the video rate of ...

We report on the operation of a highly sensitive terahertz imaging system relying on a planar metallic plasmonic crystal as a terahertz surface plasmon resonant (THz-SPR) sensor. The terahertz imaging is based on the resonantly enhanced transmission phenomenon of a periodically perforated metal film. The detection sensitivity and the imaging contrast for small amounts of substance are considera...