All-optical wavelength converters for phase modulated data signals in system experiments

• Applicant: Dr. Colja Schubert
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 78169643

This follow-up project is part of a joint research programme of two Chinese groups at the Tsinghua-University (THU, Beijing, China) and of three German groups (Technical University Berlin (TUB), University of Paderborn (UOP), Fraunhofer-lnstitute for Telecommunications - Heinrich-Hertz-Institut (HHI)). The frame of scientific cooperation is, as in the first two years of the project, the topic of contention resolution in optical burst switching (OBS) networks by wavelength conversion.The objective of this sub-project is to continue the experimental investigation on all-optical wavelength converters (AOWCs) based on the results of the previous project period. The investigated wavelength converters will use nonlinear optical effects in functional fibers like highly nonlinear fibers (HNLF), in periodically poled Lithium Niobate (PPLN) and in semiconductor optical amplifiers (SOA). The investigated devices are partly realized by the sub-projects of the other partners, e.g. the UOP (PPLN-based devices) and Tsinghua- University (SOA-based devices) and partly by the HHI within this sub-project {HNLFbased devices). The focus is on AOWCs, which are transparent to the modulation format, i.e. which can be operated with phase-modulated and amplitude modulated optical data signals. The physical layer developments in long-distance transport in the previous project period have confirmed the rapid growing importance of advanced phase modulation formats (such as differential-phase-shift keying (DPSK) and differential quadrature phase shift keying (DQPSK) [1]). Therefore the follow-up project will continue to focus on conversion of higher order phase modulated data signals.Based on the results of the previous project period, the work in next two year period will concentrate on three main topics. The first is four-wave mixing and optical parametric amplification in HNLF using advanced pumping schemes and improved functional fibers. The second is the use of a new scheme (difference and sum frequency generation) in PPLN for wavelength conversion and the basic consideration of optical parametric amplification in PPLN. Due to promising results obtained by the Chinese project partners, the third topic will be four-wave mixing in SOAs. The investigations on AOWC concepts based on SOAs will be done in close collaboration with the Chinese partners. The developed AOWC concepts will be characterized and compared using the evaluation criteria derived in the previous project period and by system experiments with symbol rates of 10, 40, 80 and 160Gbaud. Recently research on transmission systems with 100Gbit/s using symbol rates of 50 and lOOGbaud in combination with higher order modulation formats has intensified. The main reason is a growing interest, also from standardization bodies like IEEE or ITU-T, in lOOGbit Ethernet as a new technology in local, metro and long-haul transport. Therefore the use of 50 or 100 Gbaud in the system experiments will be considered, depending on the availability of the required subcomponents.To allow investigations on SOA-based AOWCs in cooperation with the Chinese partners, the initially planned work on dynamic response and transient behaviour of AOWCs at the HHI will be reduced to theoretical investigations, mainly done by the UOP and the TUB.

• DFG Programme: Research Grants