Torben Veng

Demonstration of massive wavelength-division multiplexing over transoceanic distances by use of dispersion-managed solitons

By combining a special dispersion map that has nearly constant path-average dispersion, a hybrid amplification scheme involving backward-pumped Raman gain, and sliding-frequency guiding filters, we have demonstrated massive wavelength-division multiplexing at 10 Gbits/s per channel, error free (bit-error rate, </=1x10(-9) for all channels), without the use of forward error correction, over greater than 9000 km, using dispersion-managed solitons. The number of channels (27) was limited only by a temporary lack of amplifier power and gain flatness. Terabit capacities are to be expected in the near future.

Design and manufacture of dispersion compensating fibre for simultaneous compensation of dispersion and dispersion slope

The negative dispersion slope of dispersion-compensating fibers has been optimized by increasing the width of the depressed cladding. Simultaneous compensation and dispersion slope has been demonstrated on an actual link.

Module for simultaneous C+L-band dispersion compensation and Raman amplification

A single DCF module capable of compensating the dispersion in the full C+L-band of a prototype Raman optimized NZDF has been demonstrated. The residual dispersion from 1530 to 1610 nm was controlled within /spl plusmn/0.07 ps/(nm/spl middot/km). The dispersion margin for 40 Gbit/s transmission is around /spl plusmn/60 ps/nm/sup 3/. Therefore, It will be possible to transmit DWDM 40 Gbit channels in the full C+L-band for around 850 km without any per channel dispersion trimming. The module is also an ideal lumped Raman amplifier. Using a total pump power of 1042 mW an average net gain of 10.1 dB was demonstrated from 1530 to 1607 nm. Noise figure was less than 6 dB in whole wavelength range, and OSNR from double Rayleigh scattering was better than 40 dB. The module will be ideal for use together with the Raman optimized transmission fiber in all Raman systems. Such a system will compared to a conventional system with EDFAs not require any band splitting and therefore support more channel with less loss and lower cost.

Large effective area dispersion compensating fiber for cabled compensation of standard single mode fiber

Production of wideband dispersion and dispersion slope compensating fiber with 35 /spl mu/m/sup 2/ effective area and low attenuation is demonstrated. This fiber is optimized for cable deployment in a 1:1 length ratio with standard single mode fiber.

New dispersion compensating fibres for simultaneous compensation of dispersion and dispersion slope of non-zero dispersion shifted fibres in the C or L band

A new dispersion compensating fiber with extremely high negative dispersion slope is reported. Low insertion loss between 1530 and 1610 nm is demonstrated using a new splice technique.

Dispersion compensating fibers for non-zero dispersion fibers

We have for the first time to our knowledge demonstrated a single mode dispersion compensating fiber with low PMD, low loss and high Raman gain. The fiber can compensate the dispersion as well as the dispersion slope of the high slope NZDF with RDS of 0.018 nm/sup -1/. The importance of matching not only the dispersion and dispersion slope but also the dispersion curvature has been demonstrated with a new dispersion compensating fiber for low slope NZDF with RDS of 0.018 nm/sup -1/. The residual dispersion is measured to /spl plusmn/0.02 ps/(nm km) in a wide band from 1520 to 1580 nm facilitating 40 Gbit/s transmission for more than 3000 km with no individual channel dispersion correction.

Large volume manufacturing of dispersion compensating fibers

Summary form only given. We report results of large volume production of more than 10000 km of dispersion-compensating fibers (DCF). This is equivalent to more than 1000 modules, which each can compensate 60 km of standard fiber. Reproducible large volume production of DCF is a difficult task. The design is very sensitive towards small variations in the index profile. For example, we find for our design that a 1% variation of either the core diameter or core index results in a change in dispersion of 5 and 2.5% respectively. Another challenge is to obtain low polarization-mode dispersion (PMD). DCF is more than one order of magnitude more sensitive to core ovalities than conventional telecommunication fibers due to the high core index used. Therefore extreme care has been taken to avoid core ovalities. At the same time we stimulate the mode coupling by introducing oscillatory twist into the fiber during draw. Enhanced mode coupling not only reduces the PMD, but also gives a more stable PMD value, for example during temperature cycling of DCF modules.

New dispersion compensating module for compensation of dispersion and dispersion slope of non-zero dispersion fibres in the C-band

A new single mode dispersion compensating module with very low insertion loss and PMD for C-band compensation of TrueWave-RS/sup TM/ (TWRS/sup TM/) is presented. We show experimentally that the C-band link residual dispersion varies only 0.04 ps/(nm/spl middot/km).

Erbium-doped fiber design for improved splicing performance

Fusion splicing is a well-known technique to connect a fiber pair and fusion splicers have been commercially available for this process for a long time. An important feature of a fusion splice is the coupling loss that is influenced by - among other things - the mutual spotsizes of the two fibers involved. Hence, similar fibers such as standard single mode fibers can be spliced to nearly zero loss whereas dissimilar fiber pairs may give higher loss. The latter category covers the splice combinations of erbium doped fibers that are often spliced to other fiber types such as the standard single mode fiber. We have investigated how splice loss of dissimilar fibers is influenced by fiber design with emphasis on this combination. Finally we propose a fiber design suitable for optimizing splicing capabilities of erbium doped fibers. With this design it is possible to keep fiber cutoff below 980 nm, which is of importance for practical applications, a requirement that usually conflicts with the demand for good splicing properties. An actual design, has been manufactured and splicing properties for this and the conventional design are compared.

Elliptical core polarization maintaining highly nonlinear fibres

A new design for polarization maintaining highly nonlinear fibres is presented. High birefringence, high polarization extinction ratio, and good splicing properties are obtained.