New scientific milestone in optical communications: Revolutionary chip for optical routers

The breakthrough has been published in the latest issue of the journal Optics Express.

The new chip is capable of directly routing optical packets, a feature essential to future optical routers. Besides, it incorporates the basic features in an area about 100,000 times smaller than other subsystems ­-- namely, its dimensions are 4.8x1.5mm² -- and "it is able to operate at a speed 100 times greater. This means that the routing operation can be done much faster. In the end, it's processing time that we're talking about, and the faster we get, the less time we will lose retaining the packet in the node/router, which will result in an optimization of the communication process," explains José Capmany, the ITEAM director.

The relevance of this contribution is substantial, both as regards its scientific-technical aspect and its possible commercial application. As far as its scientific importance is concerned, it should be stressed that for the first time it has become possible to implement the routing functionality by monolithic integration ­-- i.e., all the necessary components were deployed on the same chip substrate. That makes a huge difference in comparison with chip systems available to this date, which had a hybrid or mixed character, and were very bulky and costly to assemble, maintain, and operate.

"Moreover, since routing is the most complex functionality to be performed by an optical router, other tasks can be incorporated, relatively easily, into future designs," adds Capmany.

Now as regards its commercial viability, the new design is based on a general-purpose integration technology, i.e., it uses components that can be integrated easily and does not result in additional costs to the production lines of existing factories (foundries) of integrated optical circuits.

Context of breakthrough

The core of current telecommunications optical fibre networks works by establishing connections or circuits which are very similar to those established when making a telephone call. These connections reserve network resources even when no information is conveyed, which makes them inefficient.

According to ITEAM researchers, the solution to that is to chop information into smaller pieces or packets, each of which may follow a different path from source to destination in order to optimize the use of available resources. Then, for this solution to work, these packets have to be routed so that, regardless of the path that each of them follows, they all reach their destination in the proper order.

The key to an efficient routing of these packets lies in the information on their destination, or label, which is contained in the packets, and which must be processed in the intermediate nodes of the network. Currently, doing so requires converting optical information to an electrical format, which involves two major problems: first, all information has to be converted whether or not it is needed; and secondly, electrical processing capacity is limited in speed.

"Several research centres and groups around the world have spent years searching for new techniques for implementing the optical packet routing technique. However, to this date a monolithic integrated label-processing optical circuit had not been achieved," said José Capmany, head of the UPV's ITEAM.

The capacities generated at the UPV for the production of this and other integrated optical circuits have been transferred to the company VLC Photonics SL, a recently created UPV spin-off.