Phys.org August 19, 2019 An international team of researchers (France, Poland, Germany, Russia, Czech Republic) used a heavy metal alloy of mercury, cadmium and tellurium (HgCdTe) that is used for highly sensitive thermal imaging cameras. Mercury, cadmium and tellurium contents can be very precisely chosen, which makes it possible to fine-tune the band gap. The material showed properties similar to graphene, but without the issue of strong Auger scattering. When electric current is applied it gets rid of its energy in the form of terahertz radiation. By varying an additional magnetic field of only about 200 millitesla, the experts were able […]
Tag Archives: Terahertz technology
Terahertz laser for sensing and imaging outperforms its predecessors
MIT News December 10, 2018 For experiments, a team of researchers in the US (MIT, Sandia National Laboratory) fabricated an array of 10 pi-coupled wire lasers which has high constant power, tight beam pattern, and broad electric frequency tuning. The laser operated with continuous frequency tuning in a span of about 10 gigahertz, and a power output of roughly 50 to 90 milliwatts, depending on how many pi-coupled laser pairs are on the array. The beam has a low beam divergence of 10 degrees, which is a measure of how much the beam strays from its focus over distances. The […]
Light-bending tech shrinks kilometers-long radiation system to millimeter scale
Phys.org October 26, 2018 A team of researchers in the US (University of Michigan, Purdue University) used a laser to produce a pulse of visible light that lasts for one trillionth of a second. The array of antennae causes the light pulse to accelerate along a curved trajectory inside the crystal. The light pulse displaced electrons from their equilibrium positions to create dipole moments which accelerated along the curved trajectory of the light pulse resulting in the emission of synchrotron radiation much more efficiently at the terahertz range. The work demonstrates that synchrotron radiation could eventually help develop on-chip terahertz […]
Security vulnerabilities in terahertz data links
Science Alert October 15, 2018 Unlike microwaves, which propagate in wide-angle broadcasts, terahertz waves travel in narrow, very directional beams with a cone angle of less than 2 degrees. A team of researchers in the US (Brown University, Rice University, SUNY Buffalo) set up a direct line-of-site terahertz data link between a transmitter and receiver and experimented with devices capable of intercepting signal. They were able show several strategies that could steal signal without being detected by using a flat piece of metal that could redirect a portion of the beam to a secondary receiver operated by an attacker…read more. […]
New security scanners safely detect threats from people on the move
Phys.org October 8, 2018 The EU-funded SPIDERS project, has developed a ‘passive scanning’ solution which is based on a real time (up to 16 images by second), imaging system, working at millimetre wave frequencies and able to see through clothes and detect hidden objects such as liquids, powders or solids (metal or not). Crucially, the system dubbed ‘MM-Imager’, does not emit any radiation. The technology is based on the measurement of the natural radiation emitted by bodies at microwave frequencies (around 0.1THz). The SPIDERS system works in real time which makes the technology applicable to a wide range of potential […]
Tuning terahertz beams with nanoparticles
Phys.org September 6, 2018 A team of researchers in the US (UT San Antonio, Los Alamos National Laboratory) demonstrated that when an assembly of ferromagnetic core (cobalt ferrite) and a ferroelectric shell (barium titanate) is operated in external magnetic fields, it exhibits a controllable amplitude modulation when the magnetic field is applied antiparallel to the THz wave propagation direction; yet the same assembly displays an additional phase modulation when the magnetic field is applied along the propagation direction. Phase modulation is a result of stress-mediated piezoelectricity of the outer ferroelectric shell. The findings could enable tiny, high frequency transistors, create […]
Dielectric metamaterial is dynamically tuned by light
Nanowerk May 1, 2018 A team of researchers in the US (Duke University, UC San Diego) has developed a technology where each grid location of a metamaterial contains a photodoped silicon cylinder making it conductive. The size of the cylinders dictates what frequencies of light they can interact with, while the angle of the photodoping affects how they manipulate the electromagnetic waves. For demonstration they sized the cylinder to interact with terahertz waves. According to the researchers controlling terahertz waves could improve broadband communications between satellites, and lead to security technology. The approach could also be adapted to other bands […]
‘Frequency combs’ ID chemicals within the mid-infrared spectral region
Eurekalert March 15, 2018 Chemical compounds all carry distinctive absorption “fingerprints” within the mid-infrared spectral region of 2 to 12 microns. A team of researchers in the US (NIST Colorado, University of Colorado, NIST Maryland) leveraged robust fabrication and geometrical dispersion engineering of nanophotonic waveguides for multi-band, coherent frequency combs spanning 70 THz in the midinfrared (2.5 µm–6.2 µm). Precise waveguide fabrication provides significant spectral broadening with engineered spectra targeted at specific mid-infrared bands. They have numerous applications — from transferring time standards and improving GPS signals to precision spectroscopy. These sensors can significantly increase the detection sensitivity of tools […]
Taking terahertz data links around the bend
Science Daily February 6, 2018 Unlike microwaves, terahertz waves are entirely blocked by most solid objects. The assumption has been that it’s not possible to bounce a terahertz beam around — say, off a wall or two — to find a clear path around an object. A team of researchers in the US (Brown University, New Jersey Institute of Technology) bounced terahertz waves at four different frequencies off a variety of objects and showed that acceptable bit-error-rates were achievable with modest increases in signal power… read more. Open Access TECHNICAL ARTICLE