{"id":5929,"date":"2014-03-27T09:58:02","date_gmt":"2014-03-27T07:58:02","guid":{"rendered":"https:\/\/www.iemn.fr\/?p=5929"},"modified":"2014-04-01T09:13:07","modified_gmt":"2014-04-01T07:13:07","slug":"coherent-terahertz","status":"publish","type":"post","link":"https:\/\/www.iemn.fr\/en\/articles-revue-de-presse\/coherent-terahertz.html","title":{"rendered":"Coherent terahertz"},"content":{"rendered":"

\"\"<\/a>\u00a0 L\u2019IEMN et l\u2019universit\u00e9 d\u2019OSAKA ont d\u00e9montr\u00e9 une transmission t\u00e9rahertz coh\u00e9rente ultra-sensible. A la fr\u00e9quence 200 GHz, 10 Gbit\/s ont \u00e9t\u00e9 transf\u00e9r\u00e9s avec une puissance inf\u00e9rieure \u00e0 2 \u00b5W. Cette \u00e9tape importante vers les transmissions THz coh\u00e9rentes a \u00e9t\u00e9 r\u00e9alis\u00e9e dans le cadre de l\u2019ANR franco-japonaise \u00ab\u00a0WITH\u00a0\u00bb, dans laquelle l\u2019IEMN a \u00e9t\u00e9 en charge avec l\u2019universit\u00e9 d\u2019OSAKA (Groupe de T. Nagatsuma) de la r\u00e9alisation des syst\u00e8mes de transmission THz. \u00a0<\/em><\/span>\"\"<\/a><\/span><\/p>\n

Coherent THz communication at 200 GHz using a frequency comb, UTC-PD and electronic detection<\/h2>\n

Source: Electronics Letters<\/a>, Volume 50, Issue 5<\/a>, 27 February 2014, p. 386 \u2013 388<\/em><\/p>\n

Author(s): G. Ducournau<\/a> 1<\/sup> ; Y. Yoshimizu<\/a> 2<\/sup> ; S. Hisatake<\/a> 2<\/sup> ; F. Pavanello<\/a> 1<\/sup> ; E. Peytavit<\/a> 1<\/sup> ; M. Zaknoune<\/a> 1<\/sup> ; T. Nagatsuma<\/a> 2<\/sup> ; J.-F. Lampin<\/a> 1<\/sup><\/p>\n

A combined research effort in France and Japan has produced a real-time photonic-based 10 GBit\/s terahertz link with shown long term performance and an ultra-low power requirement at the receiver, using a coherent detection scheme.<\/p>\n

Laws and limits<\/h3>\n

It has been observed that the current demand for greater bandwidth to provide new services like video streaming on mobile devices is driving an increase in available data rates in a predictable pattern \u2013 Edholm\u2019s law of bandwidth. Like Moore\u2019s law for transistor counts on integrated circuits, Edholm\u2019s law observed that telecommunication data rates have doubled every 18 months, and predicts that they will continue to do so.<\/p>\n

The currently used radio bands are heavily allocated, data rate limited and near saturation. One of the avenues of research that is being explored to address this problem is terahertz communication. The challenges of working in the THz regime are balanced by the massive potential to unlock very high data rates for end-users in a large new carrier frequency space for wireless communications.<\/p>\n

 <\/p>\n

\"\"<\/a>

The transmitter (inset) and the receiver of the system.<\/p><\/div>\n

Fresh pastures<\/h3>\n

Most THz communication systems use Schottky-based direct detection to produce error-free and effective transmission systems. However, a current limitation with such systems that bars them from everyday application is that the link budgets (the losses between emission and detection) are strongly limited by the currently available emitter and receiver circuit technologies.<\/p>\n

Using coherent detection, where the receiver is phase locked to the carrier wave, can drastically reduce the minimum power required to establish and maintain an effective wireless link. This is because it reduces the required number of photons per bit of transmitted data. This, of course, reduces pressure on the link budget requirements and could open up real-world applications of Thz communication. The main challenge with coherent schemes is the need for good synchronisation between the emitter and receiver.<\/p>\n

Several research groups around the world have reported impressive results in THz communications but the key issue that remains in achieving robust THz links is obtaining long term error-free performance, which is required for real-time applications like video streaming.<\/p>\n

An enduring link<\/h3>\n

In their Letter, the combined team from Universit\u00e9 Lille1\/CNRS and Osaka University report the first realisation of a real-time 10 Gbit\/s wireless link at 200 GHz using a photonics-based source, with ultra-low required power at reception. They have demonstrated long term performance without the use of signal processing.<\/p>\n

\"\"<\/a>

An eye diagram of a 10 Gbit\/s signal sent and received using the system.<\/p><\/div>\n

\u201cThe achievement of a real-time and robust coherent wireless link using a photonics-based optical source above 120 GHz is a key point in demonstrating that photonics-based THz generation is effective for THz links,\u201d said team member Dr Guillaume Ducournau. \u201cOur achievement relies on the combination of a very stable photonics frequency comb at emission, an efficient THz emitter (a unitravelling carrier photodiode) and a very high sensitivity coherent receiver.\u201d<\/p>\n

Pocket Terahertz<\/h3>\n

The authors are now working on increasing the data-rates achievable with their system by using other carrier frequencies. The researchers responsible for the work come from THz Photonics Group of the Institut d\u2019Electronique, de Micro\u00e9lectronique et de Nanotechnologie (IEMN) at Universit\u00e9 Lille1\/CNRS and the Graduate School of Engineering Science at Osaka University. The Lille group\u2019s main interests are in THz sources using photomixing techniques at 1.55 and 0.8 \u00b5m and the application of these to wireless data links, THz instrumentation for imaging and THz near-field and nonreciprocity.<\/p>\n

Looking to the next decade in this area, Dr Ducournau sees the potential for this kind of technology to move toward ubiquity. \u201cThe realisation of THz communications may rely on stable, robust THz emission chips, including power amplifiers at emission and low noise amplifiers at reception. Solid-state electronics are going higher and higher, and in the next decade all the building blocks of traditional communications at Wi-Fi frequencies will be available, leading to ultra-fast connections in the end-user\u2019s pocket.\u201d<\/p>\n

>> PDF version<\/a><\/p>\n

 <\/p>","protected":false},"excerpt":{"rendered":"

\u00a0 IEMN and OSAKA University have demonstrated ultra-sensitive coherent terahertz transmission. At 200 GHz, 10 Gbit\/s were transferred with a power of less than 2 \u00b5W. This major step towards coherent THz transmissions was achieved within the framework of the Franco-Japanese ANR \"WITH\", in which IEMN was in charge [...].<\/p>","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8,5],"tags":[],"class_list":["post-5929","post","type-post","status-publish","format-standard","hentry","category-actualites","category-articles-revue-de-presse"],"_links":{"self":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/5929","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/comments?post=5929"}],"version-history":[{"count":0,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/posts\/5929\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/media?parent=5929"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/categories?post=5929"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.iemn.fr\/en\/wp-json\/wp\/v2\/tags?post=5929"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}