Showing posts with label Cordis. Show all posts
Showing posts with label Cordis. Show all posts

Tuesday, November 20, 2018

Graphene boosts GHz signals into terahertz territory

According to scientists, graphene can generate clock speeds that transcend today’s GHz limitations. Here’s how.



https://cordis.europa.eu/news/rcn/130280_en.html



Graphene – a one-atom-thick layer of hexagonally arranged carbon atoms – is the thinnest and strongest material known to man and an excellent conductor of heat and electricity. Since 2004, when researchers discovered how to extract it from graphite, graphene has opened new windows of opportunity in the world of science and technology. Over the past decade, scientists have predicted that its unique structure would make it especially efficient in converting optical or electronic signals into signals of much higher frequencies. However, all efforts to prove this were unsuccessful.

Now, for the first time, a team of researchers, two of whom are supported by the EU-funded project EUCALL, have proved that graphene is actually able to convert electronic signals into signals in the terahertz range, with trillions of cycles per second. The team’s findings are presented in a
study published in the journal ‘Nature’.

Non-linear interaction

The silicon-based electronic components used today generate clock speeds in the GHz range, where 1 GHz is equal to 1 000 million cycles per second. The scientists demonstrated that graphene can convert signals with these frequencies into signals with frequencies that are thousands of times higher than those created by silicon.

What makes this feat possible is the highly efficient non-linear interaction between light and matter that occurs in graphene. The researchers used graphene containing a large number of free electrons that originated from the interaction between graphene and the substrate onto which it was deposited. When these electrons became excited by an oscillating electric field in room-temperature conditions, they rapidly shared their energy with bound electrons in the material. The electrons therefore reacted like a heated fluid, changing from liquid to vapour form inside the graphene within trillionths of a second. This transition led to powerful, rapid changes in the material’s conductivity, multiplying the frequency of the original GHz pulses.

“We have now been able to provide the first direct proof of frequency multiplication from gigahertz to terahertz in a graphene monolayer and to generate electronic signals in the terahertz range with remarkable efficiency,” says co-author and Helmholtz Zentrum Dresden-Rossendorf (HZDR) senior scientist Dr Michael Gensch in a
press release posted on the project partner’s website.

High conversion efficiency

The frequencies of the original electromagnetic pulses that were generated at HZDR’s TELBE terahertz facility ranged between 300 and 680 GHz. The scientists converted them into signals with three, five and seven times the initial frequency. “These conversion efficiencies are remarkably high, given that the electromagnetic interaction occurs in a single atomic layer,” the authors state in their study.

The groundbreaking discovery supported by EUCALL (European Cluster of Advanced Laser Light Sources) makes graphene a promising candidate for the nanoelectronics of the future.
For more information, please see:
EUCALL project website



Thursday, February 4, 2016

Cordis-Graphene for terahertz communications



RASTREO Result In Brief

Project reference: 300934
Funded under: FP7-PEOPLE
Country: Switzerland
http://cordis.europa.eu/result/rcn/175078_en.html


Graphene has attracted tremendous scientific interest due to its exceptional electrical and mechanical properties. EU-funded researchers explored the use of graphene for a reconfigurable antenna operating at terahertz (THz) frequencies.
Graphene for terahertz communications
THz frequencies hold a large number of potential applications in the field of telecommunications, as well as imaging and sensing. But for all these applications THz antennas are a necessity. Within the EU-funded project RASTREO (Multi-reconfigurable antenna solutions based on reflectarray technology), researchers studied the properties of graphene with the aim of developing a THz reflectarray.

A reflectarray combines all the advantages of a parabolic reflector with the planar design of a phased array of antennas. Graphene is a mono atomic layer of carbon atoms arranged in a honeycomb structure, a semiconductor that allows the propagation of plasmonic modes at THz frequencies. Moreover, its conductivity can be efficiently controlled by an electric field.

RASTREO researchers demonstrated dynamic tuning at a frequency of 1.3 THz. The reflection coefficient of a square graphene patch as a function of both the patch size and the chemical potential was also computed. The maximum phase variation was obtained for a graphene patch of 10 μm, reaching about 300 degrees which is enough to produce a pencil beam.

The results obtained laid the groundwork for the design and analysis of a reflectarray. In the case of a conventional reflectarray, 489 gold elements with a cell size of about 100 μm would be needed. RASTREO researchers used more than 25 000 graphene elements. The experimental prototype was fabricated monolithically, due to which the high number of elements did not have any impact on the cost.

The graphene-based reflectarray has been designed to radiate a pencil beam with a loss varying between 0.5 dB and 6 dB between1.1 THz and 1.6 THz. The details of its design and the performance evaluation have been described in two articles published in peer-reviewed journals and presented at international conferences.

The RASTREO project has opened a very promising research line with exciting applications in indoor and satellite communications and has already attracted significant interest for future collaborations.

Tuesday, January 5, 2016

Success for cutting edge cultural artefact imaging technique



Terahertz imaging technology has the potential to help conservationists and academics better understand the history behind cultural artefacts.

http://cordis.europa.eu/news/rcn/124539_en.html

The EU-funded TISCH project has demonstrated that terahertz imaging and spectroscopy can be a viable, non-destructive and non-invasive tool to aid the retrieval and analysis of images of obscured features of artwork. Through a Marie Curie Postdoctoral Research Fellowship, Dr Bianca Jackson from the University of Reading in the UK was able to apply this technique to inspect layers of paint, detect structural defects in ceramics and image the physical structure of paintings and manuscripts.

‘Institutions that carry out cultural heritage research don't have a lot of extra money for emerging technology, but they do have the hearts and minds of the people – folks love to talk about what is being done with technology to better understand the mysterious Mona Lisa, or whether or not a sarcophagus contains Queen Neferititi,’ says Jackson. ‘So one of best ways to reduce costs and increase the accessibility of terahertz technology to open up new and interesting areas of applied research.’

In the last 15 years there has been exponential growth in terahertz technology and applied research, along with increasing interest from the pharmaceutical, biomedical, security and aerospace industries. ‘In the US, 9/11 and the Columbia disaster lead to a large influx of research funding, which has helped to drive this growth,’ explains Jackson.

However, the cost of terahertz systems is still much higher than other well-established technologies, which is why further applied research is needed. Furthermore, terahertz spectroscopic imaging has only been used in the field of cultural heritage over the last five years or so, and as a result, its utility to conservation has not been extensively demonstrated.

In order to address this, Jackson examined the walls of several European churches in England, France and Latvia, where centuries-old paintings were hidden behind many layers of plaster and plain paint. ‘We use a time-domain terahertz system, which has a pulse that allowed us to separate out the signals from the top and sub-surface layers,’ she explains. ‘This enabled us to find some designs behind some perfectly plain white walls.’

Jackson also scanned a Palaeolithic wall etching of a bird obscured by flow rock and investigated heritage conservation-friendly materials that can be safely applied to works in order to improve the signal to noise quality of the terahertz image. ‘Most recently, we started working with the Tate Museum to use terahertz imaging to diagnose flawed areas of ceramic glaze on outdoor sculptures left out in the rain,’ she adds. ‘While the TISCH project is almost finished, I’m very excited about the implications of our work with the Tate.’

Jackson is confident that the TISCH project represents a positive step forward, with similar cultural heritage projects also now coming on line. ‘Horizon 2020 is funding a project called IPERION CH, through which there is a great programme called MOLAB (short for mobile laboratory) that is accepting proposals for research using various advanced diagnostic technologies for cultural heritage,’ she says. ‘Recently, they added terahertz time-domain spectroscopy and imaging as an option. I've been encouraging interested conservators to apply for MOLAB access, and I’ve been offering my aid.’

For further information please visit:
University of Reading website

Source: Based on an interview with the project coordinator.

Tuesday, November 10, 2015

CORDIS-Micromachined terahertz systems -a new heterogeneous integration platform enabling the commercialization of the THz frequency spectrum



Objective
This project envisions the wide-spread use of low-cost THz technology in our society, enabled by the proposed micromachined heterogeneous integration platform, which provides an unprecedented way to highly-integrated, volume-manufactuable, cost- and energy-efficient, reconfigurable submillimeter-wave and terahertz (THz) systems. The proposed THz integration platform is envisioned to initiate an important transition in industrial microwave-systems manufacturing and is expected to finally enable the large-scale commercialization of the heavily sought-after frequency space between 100 GHz and 1 THz. In line with technology convergence of advancing microwave semiconductor technology according to internal and external roadmaps, the proposed THz microsystem platform is envisioned to accommodate multiple generations of future THz products in different application fields. The concrete business and lead application case is THz microsystems enabling compact, low-cost point-to-point high-speed communication links in the frequency space between 100 GHz and 500 GHz, to be deployed in a scenario of a high-density small-cell base-station network providing ubiquitous high-speed internet access to mobile communication devices in urban environment. The key technology end-user driving the primary prototype development and demonstration of a complete THz communication link is Ericsson. A secondary prototype developed in M3TERA is on a multi-function adaptive THz sensor platform for different millimeter-wave sensing applications in society, including food quality control and food safety monitoring, medical diagnosis, and industrial sensing. The key manufacturing partner in this industry-driven proposal is the high-volume semiconductor and microsystems manufacturer IFAT, who also provides system packaging concepts. Project management of this 3-years project with 7 participants in 4 EU countries is done by a professional company with an exceptional career track in EU project management.
Coordinator
TECHNIKON FORSCHUNGS- UND PLANUNGSGESELLSCHAFT MBH
Project details
Total cost:
EUR 4 255 743,75
EU contribution:
EUR 3 742 961,25
Coordinated in:
Austria
Topic(s):
Call for proposal:
H2020-ICT-2014-1
Funding scheme:
RIA - Research and Innovation action


Saturday, April 11, 2015

Exciton–photon dynamics in graphene


Exciton–photon dynamics in graphene [Print to PDF] [Print to RTF]
An EU-funded project studied the physics underpinning light–matter interaction in two-layered graphene with a band gap. Project findings will pave the way to developing pioneering optoelectronic devices.
Exciton–photon dynamics in graphene
Excitons — neutral quasiparticles that exist in semiconductors — demonstrate strong coupling with light. Embedding bilayer graphene with a band gap in optical microcavities allows controlling interaction that can lead to a strong coupling regime. Such an interaction results in the formation of a new kind of quasiparticle known as exciton-polariton that is a half-light and half-matter bosonic quasiparticle.

With EU funding of the project 'Bilayer graphene exciton polariton' (BIGEXPO), scientists sought to enhance understanding of the bilayer graphene coupling to the photonic field of a microcavity. Based on a non-perturbation approach, BIGEXPO focused on studying the phenomena taking place when a dipole layer such as a graphene sheet interacts with an electromagnetic field.

Study findings demonstrated that the Purcell effect breaks down — counterintuitively, the spontaneous emission rate plummets in a strong coupling regime. Furthermore, scientists concluded that current approximations to photonic emissions have to be modified.

Another task was to develop a microscopic theory describing the coupling between excitons in bilayer graphene and photons. Once completely developed, this theory should provide a comprehensive description of the underlying physics of light–matter interaction. The coupling non-perturbative nature should account for extraordinary physical effects.

BIGEXPO sought to enhance understanding of the physical processes governing the exciton–photon dynamics in microcavities. Considering its large excitonic dipole moment, the graphene microcavity system could push back the frontiers of research into solid-state cavity quantum electrodynamics. Not only will it allow observing a novel, strongly correlated light–matter coupling regime, but also lead to a new generation of terahertz and mid-infrared super-efficient optoelectronic devices.