Researchers of the Institute of Electrical and Optical Communications Engineering (INT) at the University of Stuttgart and the Institut für Mikroelektronik Stuttgart (IMS CHIPS) achieved a new world record in the energy efficient integration in silicon. This is an important step to decrease the energy consumption of data transfer in internet and telecommunication. The researchers optimized aperiodic grating couplers in the nanometer range with a new developed backside metal mirror. Through this new method a record coupling efficiency of 87 percent between optical fibers and photonic integrated waveguides on silicon wafers has been achieved.
The internet and telecommunications are based on an optical core network that connects cities
worldwide using glass fibers. These can carry light with very low losses over long distances. Based
on a study published by CISCO, the mobile data transfer (smartphones) will solely increase from 885
petabytes per month (end of 2012) up to ten exabytes per month in the year 2017. To avoid a similar
increasing energy consumption of our telecommunication systems, more efficient networks have to be
developed, which represents nowadays a very interesting and actual research field.
Researchers of the INT and IMS CHIPS have developed a fabrication process to realize complex
sender and receiver structures that are integrated on silicon wafers. Hitherto existing optical
senders and receivers are based on indium phosphide substrates, which are available only in small
dimensions and to very high costs. Experts predict that optical connections will be necessary in
the home computer of the year 2020 to exchange the huge amount of data between individual
components of the computer. The used light has a frequency of around 192 Terahertz and hence can
offer bandwidths of several Terahertz and data rates beyond 1 Terabit/s. Thus, worldwide
researchers try to develop new components to make use of these tremendous data rates in commercial
products. Since silicon is transparent at the used light frequency, this material can be utilized
in waveguiding structures. Computing based on photons in nanoelectronic circuits can be then
achieved in future computer components.
For this purpose light has to be efficiently guided in silicon waveguides and coupled from one
component to another. The resulting energy losses have to be kept as small as possible. Researchers
of the University of Stuttgart achieved a new world record in coupling efficiency between optical
fibers and integrated silicon waveguides based on the new developed aperiodic grating coupler
structures that are fabricated using the technology process of IMS CHIPS. With a record of 87
percent and a bandwidth of around 40 nm the new structures can pave the way for more efficient
integration of optical senders and receivers in silicon.
In this complementary-metal-oxide-semiconductor fabrication process other components such as
polarization beam splitters based on grating structures are also realized. The University of
Stuttgart and IMS CHIPS achieved here as well promising results, which makes them leading in the
integration of optical components in silicon. The researches will be concretized in commercial
products with the support of industrial partners to achieve cost effective integrated senders and
receivers in silicon that enable data rates beyond 1 Terabit/s.
The results will be published in September at the European Conference on Optical
Communications in London (http://www.ecoc2013.org/).
More information
Prof. Manfred Berroth, Wissem Sfar Zaoui, University of Stuttgart, Institute of Electrical
und Optical Communications Engineering (INT), Tel. 0711/685-67922, -67892, E-Mail: berroth (at)
int.uni-stuttgart.de, wissem.sfarzaoui (at) int.uni-stuttgart.de
Prof. Joachim Burghartz, Dr. Jörg Butschke und Dr. Florian Letzkus, Institut für Mikroelektronik
Stuttgart (IMS), Tel: 0711/21855-200, -453, -451,
E-Mail: burghartz (at) ims-chips.de, butschke (at) ims-chips.de, letzkus (at)
ims-chips.de
Andrea Mayer-Grenu, University of Stuttgart, Dept. Hochschulkommunikation, Tel. 0711/685-82176,
E-Mail: andrea.mayer-grenu (at) hkom.uni-stuttgart.de
INT
The institute of Electrical and Optical Communications Engineering belongs to the faculty of “
Computer Science, Electrical Engineering and Information Technology” at the University of
Stuttgart. Under the direction of Prof. Manfred Berroth, the INT employs 22 members, active in
research, teachings, and administration. The main competences of the institute are modeling,
design, and measurement of integrated electrical and photonic circuits and efficient power
amplifiers. The institute is also a member of the Stuttgart Center of Photonic Engineering (SCoPE),
which supports the interdisciplinary cooperation between the different departments of physics,
electrical and mechanical engineering at the University of Stuttgart.
IMS CHIPS
The Institut für Mikroelektronik Stuttgart (IMS CHIPS) is a public law foundation in
Baden-Württemberg. It is engaged in industry oriented research and development in the fields of
silicon technology, application specific integrated circuits (ASIC), nanostructuring, and imaging
sensors. The institute offers complete solutions for small and medium enterprises and is a partner
of national and international large concerns. Under the direction of Prof. Joachim Burghartz, IMS
CHIPS is composed of 80 highly qualified employees, which are involved in the development of new
products in the microelectronics and microsystems and their transfer into production lines.