Hans Wolfgang

Bio: Hans Wolfgang is an academic researcher from Alcatel-Lucent. The author has contributed to research in topics: Local area network & Connectionless communication. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Optical subscriber interconnect system

Abstract: To match the inherent needs of data traffic, office communications demand medium-speed connectionless packet transport in addition to circuit-switched voice and data transmission. Optical solutions to this requirement should be low in cost rather than extremely high in performance to be cost competitive with copper systems. A subscriber-premises system will be proposed which combines a digital private automatic branch exchange (PABX) with local area network (LAN) functionality. It is based on a double-star passive optical network, extending to optical wall outlets. The subsets with telephone functionality provide the opto/electrical conversion and give access to the packet channel via Terminal Adaptors (TA). Different types of customer LANs may coexist on the same network, since their data frames are embedded in an intermediate MAC-layer. The feasibility of transmission over multimode fibers at not aggregate bit rate of approx. 140 Mb/s at 1300 nm downstream and 780 nm upstream allowing the use of low-cost components (e.g. 780 nm compact-disc laser diodes) has been experimentally investigated. Calculations predict cost-of-ownership parity with conventional copper-based PABXs without LAN functionality and a cost-advantage over the usual separate LAN+PABX installations. The network topology, protocol and the implications of multimode transmission on the system will be discussed.

How modal noise in multimode fibers depends on source spectrum and fiber dispersion

Abstract: The speckle contrast for multimode fibers, and thus the modal noise, is essentially given by the impulse response of the fiber and the power spectrum of the source. Theoretical and experimental results show that laser sources with a large spectrum of narrow longitudinal modes may cause high speckle contrast and important modal noise over more than 1-km length in graded-index multimode fibers.