Terahertz radiation still lies in a metrological no man's land – a metrology gap. The Physikalisch-Technische Bundesanstalt (PTB) can now close this gap. For the first time, a commercial Terahertz laser was traced back to the international system of units (SI) by measuring its output power absolutely.
PTB achieved this success with a power meter which had been calibrated beforehand against a cryogenic radiometer, Germany's primary standard for power measurement of electromagnetic radiation. Therefore, this laser, namely a SIFIR-50 manufactured by the US company Coherent Inc., is the first THz laser in the field with a reliably proven output power enabled by a novel calibration capability set up at the PTB.
Terahertz radiation refers to frequencies from 0.3 THz to 10 THz, which are located in between microwaves and infrared radiation at long wavelengths. These are the limits of two different mechanisms for generating radiation: microwaves are produced electronically by semiconductors and infrared radiation in contrast, optically by means of lasers. This Terahertz gap has only recently been penetrated, but it shows to be promising for a variety of applications. Meanwhile, Terahertz radiation is used for spectroscopy, analytical science and astronomy. As technological innovations have noticeably improved the generation and detection of THz radiation, more and more areas have been added: testing of materials, security checks at airports, biological and medical science, quality inspection of foodstuffs and agricultural goods, global environmental monitoring and information and communication techniques, as well. All of these applications benefit from reliable power measurement in the THz region.
That is why a world leader in laser technology, the company Coherent Inc., and a leading institute of metrology, the Physikalisch-Technische Bundesanstalt, have joined forces to improve the measurement of the power of Terahertz lasers and to trace it back to the SI units by comparing it to a national standard.
The Coherent SIFIR-50 laser which was operated at 2.5 THz for the first power measurement is the core instrument of a new facility for the determination of the THz radiant power in SI units and for the calibration of THz detectors. It is a far-infrared molecular gas laser pumped by an integrated, frequency stabilized, tunable 50 W CO2 laser. Dr. Andreas Steiger of PTB Berlin explains: "The unique feature of the system is its Fabry-Perot lock used to control the operating frequency of the CO2 laser which is optimal for pumping the vibrational transitions of the gas molecules". Combined with its thermally-compensated THz resonator and pump optics design, the SIFIR-50 delivers stable THz radiation, tunable from 1 THz to 7 THz, to several rotational transitions of the molecules in use. The wide tuning range is four times larger than the whole visible spectrum and contains a variety of discrete THz lines in many different gases. Steiger is confident: "The performance and beam quality of the laser enables PTB to take a large step in bridging the metrology gap between ultra high-frequency electronics and far-infrared optics in the near future."
Dr. Andreas Steiger, PTB Working Group 7.34 "Terahertz Radiometry", Tel. (+49) 30 3481 7532, e-mail: Andreas.Steiger@PTB.de
Petra Wallenta, Coherent, PR Europe, e-mail: Petra.Wallenta@coherent.com, Internet: http://www.coherent.com.
Fraunhofer researchers develop measuring system for ZF factory in Saarbrücken
21.11.2017 | Fraunhofer-Institut für Zerstörungsfreie Prüfverfahren IZFP
New manufacturing process for SiC power devices opens market to more competition
14.09.2017 | North Carolina State University
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
23.11.2017 | Information Technology
23.11.2017 | Physics and Astronomy
23.11.2017 | Life Sciences