Bernd Franz

Experimental Evaluation of Principal Mode Groups as High-Speed Transmission Channels in Spatial Multiplex Systems

The application of principal mode groups for the transmission of high bit rate data over OM4 graded-index multimode fiber (MMF) has been experimentally investigated. Eight principal mode groups have been identified as being suitable for spatially separated transmission channels at a wavelength of 1550 nm for the OM4 fiber. It has been shown that each of the eight mode groups can be used for the transmission of 10-Gb/s data over a 5-km-long graded-index MMF.

High speed OFDM data transmission over 5 km GI-multimode fiber using spatial multiplexing with 2×4 MIMO processing

We demonstrated experimentally the transmission of 8 Gbit/s data using the OFDM format over 5 km graded-index multi-mode fiber combining modal diversity, coherent transmission and direct detection with 2×4 MIMO signal processing.

40 Gbit/s quaternary dispersion supported transmission over 31 km standard singlemode fibre without optical dispersion compensation

Using electrical time division multiplexing and demultiplexing, 40 Gbit/s transmission over an uncompensated standard singlemode fibre link is reported for the first time. The system includes a decision circuit realised in SiGe HBT technology.

Mode group division multiplexing in graded-index multimode fibers

Data transmission over multimode fibers has the potential to considerably increase the capacity limit of single-mode fibers by exploiting the spatial dimension. For long-haul systems, mode division multiplexing using one mode per channel in a few-mode fiber requires coherent detection in conjunction with digital multiple input multiple output (MIMO) processing for signal separation. In the following we focus on spatial multiplexing using mode groups rather than spatial modes in standard graded-index multimode fibers. In combination with on-off keying (OOK) modulation and direct detection, these systems might be advantageous for access- and connection-related applications, e.g., for super computer interconnects or in the near metro region at link lengths shorter than about 10 km. In this paper we study the potential of mode groups for mode group division multiplexing (MGDM). Single-mode group transmission experiments at 10 Gb/s per mode group, experimental mode group launching by phase mask, and concepts for passive optical mode demultiplexers are discussed.

Mode group multiplexing over graded-index multimode fiber

Data transmission over multi-mode fibers (MMF) has the potential to increase considerably the capacity limit of singlemode fibers (SMF) by exploiting the spatial dimension. Spatial multiplex using standard graded-index multimode fibers (GI-MMF) in combination with OOK modulation and direct detection might be advantageous for short haul transmission systems. The application of principal mode groups provides the possibility to eliminate the need for multiple-input multiple-output (MIMO) processing, especially if a fiber supporting a large number of modes is used for the transmission. Spatial multiplex using principal mode groups as individual transmission channels has been experimentally investigated at the example of a data transmission over a 2 km long OM4 graded-index multi-mode fiber. Eight principal mode groups have been identified being suitable as spatially separated transmission channels for 10 Gbit/s data at a wavelength of 1550 nm.

Serial 107 Gbit/s (2x53.5 Gbit/s NRZ-VSB-Polmux) transmission over 15 km SSMF with electronic dispersion compensation

We report on serial 107 Gbit/s (2x53.5 Gbit/s NRZ-VSB-Polmux) transmission over ~15 km SSMF applying only electronic dispersion compensation with a linear equalizer.

Spatial multiplexers and demultiplexers for mode group division multiplex

Spatial multiplexer and demultiplexer are beneath the multimode fiber the key components for a transmission system using mode or mode group division multiplexing (MDM or MGDM). The spatial multiplexer converts the LP01 modes of the incoming singlemode fibers into the desired modes or mode groups of the multimode fiber. The spatial demultiplexer performs the inverse operation. This paper gives an overview on different kinds of spatial multiplexers/demultiplexers and introduces a first experimental result of a 4:1 spatial multiplexer in combination with a standard OM4 graded-index multimode fiber.

Optical Ethernet—Flexible Optical Metro Networks

Enhanced flexibility in optical transport networks is a key requirement to support dynamic traffic load in packet-based networks. Today, flexibility is achieved by packet switches linked by static point-to-point transport connections. Wide-stretched synchronization patterns, line coding schemes, and forward error correction (FEC) frames prohibit flexibility right at the transport layer. We introduce a new optical transport concept that combines packet aggregation with a multipoint-to-point line coding and FEC processing. This concept avoids the quadratic full mesh scalability problem of other aggregated switching technologies such as, e.g., wavelength switching. It combines the flexibility of a distributed Ethernet switch and the performance of a leading edge optical transport system.

Electronic mitigation for 10, 40 and 100G

Electronic dispersion compensation by analog and digital equalizers enable a considerable increase of high bit rate optical transmission system tolerances. Electronic equalizers are small size and low power consumption subsystems suitable for compact transponder integration.

Performance improvement of 43 Gbit/s Apol-RZ-DPSK transmission by electronic equalization

The application of electronic distortion equalization (EDE) for Apol-RZ-DPSK has been evaluated experimentally and numerically. EDE extends the DGD tolerance by ~30%, if the polarization will be controlled.