The rising traffic demand in mobile networks is pushing the capacity need, especially in the access network. Wireless access integrated with the operator optical fiber network offers mobility and easiness of deployment. The challenge is the provision of wireless broadband capacity paired with the increasing traffic demands. The paper describes a point-to-multipoint fronthaul distribution wireless network at D-band (141 – 148.5 GHz) fed with point-to-point backhaul transport links at G-band (275 – 305 GHz), providing tens of Gb/s data rate. The system is under development in the frame of the European Commission Horizon 2020 ULTRAWAVE “Ultra capacity wireless layer beyond 100 GHz based on millimeter wave”. The D-band transmission hubs are connected to the optical core network through Gb/s class G-band links, based on a microwave photonic transmitter employing uni-traveling-carrier photodiodes (UTC-PD). A field test in real environment is planned to demonstrate the ULTRAWAVE system breakthrough.
Traveling-wave tubes (TWT) with microstrip planar slow wave structures (SWS) have attracted an increasing interest thanks to low operating voltage and size of the tube, as well as compatibility with modern microfabrication technologies. In this work, we report the results of design, fabrication, and experimental cold-test study of planar meander-line SWSs for millimeter-band TWTs (V-, W-, and D-band). SWS samples have been fabricated using the technology based on magnetron sputtering and subsequent laser ablation.
Continuous-wave THz digital holography (DH) is an advanced interference imaging technique, which can be used to reconstruct the amplitude and phase distributions of a sample. In this paper, an in-line holographic system is presented using a 300 GHz source and a highly sensitive broadband CMOS TeraFET (THz Field-Effect Transistor) detector. Numerical reconstruction is achieved using the angular spectrum approach. Experimental results are presented for a sample made of Polyvinyl Chloride (PVC). The results demonstrate that THz digital holography can be readily applied to perform quantitative metrology and may find many applications in 3D digital imaging and microscopy.
We have studied several sensor concepts for biomedical applications operating in the millimeter wave and terahertz range. On one hand, rectangular waveguide structure were designed and extended with microfluidic channels. In this way a simple analysis of aqueous solutions at various waveguide bands is possible. In our case, we focused on the frequency range between 75 GHz and 110 GHz. On the other hand, planar sensor structures for aqueous solutions have been developed based on coplanar waveguides. With these planar sensors it is possible to concentrate the interaction volume on small sensor areas, which achieve a local exposure of the radiation to the sample. When equipping the sensor with microfluidic structures the sample volume could be reduced significantly and enabled a localized interaction with the sensor areas. The sensors are designed to exhibit a broadband behavior up to 300 GHz. Narrow-band operation can also be achieved for potentially increased sensitivity by using resonant structures. Several tests with Glucose dissolved in water show promising results for the distinction of different glucose levels at millimeter wave frequencies. The planar structures can also be used for the exposure of biological cells or cell model systems like liposomes with electromagnetic radiation. Several studies are planned to distinguish on one hand the influence of millimeter wave exposure on biological systems and also to have a spectroscopic method which enables the analysis of cell processes, like membrane transport processes, with millimeter wave and terahertz frequencies by focusing the electric field directly on the analyzing sample.
Naomi Alexander, Byron Alderman, Fernando Allona, Peter Frijlink, Ramón Gonzalo, Manfred Hägelen, Asier Ibáñez, Viktor Krozer, Marian Langford, Ernesto Limiti, Duncan Platt, Marek Schikora, Hui Wang, Marc Andree Weber
The challenge for any security screening system is to identify potentially harmful objects such as weapons and explosives concealed under clothing. Classical border and security checkpoints are no longer capable of fulfilling the demands of today’s ever growing security requirements, especially with respect to the high throughput generally required which entails a high detection rate of threat material and a low false alarm rate. TeraSCREEN proposes to develop an innovative concept of multi-frequency multi-mode Terahertz and millimeter-wave detection with new automatic detection and classification functionalities. The system developed will demonstrate, at a live control point, the safe automatic detection and classification of objects concealed under clothing, whilst respecting privacy and increasing current throughput rates. This innovative screening system will combine multi-frequency, multi-mode images taken by passive and active subsystems which will scan the subjects and obtain complementary spatial and spectral information, thus allowing for automatic threat recognition. The TeraSCREEN project, which will run from 2013 to 2016, has received funding from the European Union’s Seventh Framework Programme under the Security Call. This paper will describe the project objectives and approach.
We present recent developments of two kinds of compact room-temperature detectors for terahertz radiation. These are
asymmetrically-shaped bow-tie diodes, and field-effect transistors with sub-micrometer channel lengths. Both kinds of
detectors exhibit fast response times which allow operating them as mixers, moreover they are suitable for the fabrication
of large multi-pixel arrays. Here, we provide data on the experimental performance of detector arrays and show their
applicability in coherent terahertz imaging systems. In addition, we demonstrate real-time operation of a 12×12-pixel
CMOS camera in power-detection mode at 590 GHz.
We explore terahertz imaging with CMOS field-effect transistors exploiting their plasmonic detection capability and the
advantages of CMOS technology for the fabrication of THz cameras with respect to process stability, array uniformity,
ease of integration of additional functionality, scalability and cost-effectiveness. A 100×100-pixel camera with an active
area of 20×20 mm² is physically simulated by scanning single detectors and groups of a few detectors in the image plane.
Using detectors with a noise-equivalent power of 43 pW/√Hz, a distributed illumination of 432 μW at 591.4 GHz, and an
integration time of 20 ms (for a possible frame rate of 17 fps), this virtual camera allows to obtain images with a
dynamic range of at least 20 dB and a resolution approaching the diffraction limit. Imaging examples acquired in direct
and heterodyne detection mode, and in transmission and reflection geometry, show the potential for real-time operation.
It is demonstrated that heterodyning (i) improves the dynamic range substantially even if the radiation from the local
oscillator is distributed over the camera area, and (ii) allows sensitive determination of object-induced phase changes,
which promises the realization of coherent imaging systems.
An active system for stand-off imaging operating in a frequency range from 234 GHz to 306 GHz is presented. Imaging
is achieved by combining a line array consisting of 8 emitters and 16 detectors with a scanning cylindrical mirror system.
A stand-off distance of 7-8 m is achieved using a system of mirrors with effective aperture of 0.5 x 0.5 meter.
Information about range and reflectivity of the object are obtained using an active FMCW (frequency modulated
continuous wave) radar operation principle. Data acquisition time for one line is as short as 1 ms. Synthetic image
reconstruction is achieved in real-time by an embedded GPU (Graphical Processing Unit).
M. Dispenza, F. Brunetti, C.-S. Cojocaru, A. de Rossi, A. Di Carlo, D. Dolfi, A. Durand, A. Fiorello, A. Gohier, P. Guiset, M. Kotiranta, V. Krozer, P. Legagneux, R. Marchesin, S. Megtert, F. Bouamrane, M. Mineo, C. Paoloni, K. Pham, J. Schnell, A. Secchi, E. Tamburri, M. Terranova, G. Ulisse, V. Zhurbenko
Within the EC funded international project OPTHER (OPtically Driven TeraHertz AmplifiERs) a considerable
technological effort is being undertaken, in terms of technological development, THz device design and integration. The
ultimate goal is to develop a miniaturised THz amplifier based on vacuum-tube principles
The main target specifications of the OPTHER amplifier are the following:
- Operating frequency: in the band 0.3 to 2 THz
- Output power: > 10 mW ( 10 dBm )
- Gain: 10 to 20 dB.
The project is in the middle of its duration. Design and simulations have shown that these targets can be met with a
proper device configuration and careful optimization of the different parts of the amplifier. Two parallel schemes will be
employed for amplifier realisation: THz Drive Signal Amplifier and Optically Modulated Beam THz Amplifier.
A recent study initiated by the European Space Agency aimed at identifying the most promising technologies to significantly improve on the generation of coherent electromagnetic radiation in the THz regime. The desired improvements include, amongst others, higher output powers and efficiencies at increasingly higher frequencies, wider tunability and miniaturization. The baseline technologies considered revolve around Photomixing and novel laser based technologies compared to all electronic techniques. Some of the most significant findings will be presented together with technological developments and experimental results selected for medium to short term development. These technologies include advanced p-i-n photomixer with superlattice structures and, THz quantum cascade lasers. Recent results achieved in these fields will be put into the potential perspective for the respective technology in the future.
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