Malte Schneiders

Cumulative nonlinear phase shift as engineering rule for performance estimation in 160-Gb/s transmission systems

Investigations in high-speed optical systems, based on a line data rate of 160 Gb/s, identified the nonlinear single-channel effects self-phase modulation, intrachannel four-wave mixing, and intrachannel cross-phase modulation as the main limiting factors beside polarization-mode dispersion, chromatic dispersion, and dispersion slope. In this letter, we investigate the impact of nonlinear single-channel effects on the transmission performance of 160-Gb/s systems. We determine an analytical engineering rule for the estimation of system performance and system reach for 160-Gb/s systems, considering various fiber types and amplifier concepts.

Analysis of Crosstalk in Mixed 43 Gb/s RZ-DQPSK and 10.7 Gb/s DWDM Systems at 50 GHz Channel Spacing

In DWDM field experiments over 1047 km of standard fiber and in simulations we analyze the impact of crosstalk on a 43 Gb/s RZ-DQPSK channel both by 10.7 Gb/s OOK and 43 Gb/s RZ-DQPSK neighbors at 50 GHz channel spacing.

Field transmission of 8 /spl times/ 170 gb/s over high-loss SSMF link using third-order distributed Raman amplification

This paper reports on the field transmission of N/spl times/170-Gb/s over high-loss fiber links using third-order distributed Raman amplification (DRA) in a commercially operated network of Deutsche Telekom. It gives an overview of the key technologies applied for the realization of an 8 /spl times/ 170 Gb/s (1.28 Tb/s) dense wavelength division multiplexing (DWDM) system demonstrator and summarizes long-haul transmission experiments with terabit-per-second capacity over European fiber infrastructure. Third-order DRA enabled repeaterless transmission of 1 /spl times/ 170 Gb/s and 8 /spl times/ 170 Gb/s over links of 185- and 140-km field fiber, respectively. Including an additional 25 km of lumped standard single-mode fiber (SSMF) at the end of the span, a total loss of 61 and 44 dB, respectively, was bridged.

System optimization and significant reach extension using alternating dispersion compensation for 160 Gbit/s transmission links.

Dispersion post compensated 160 Gbit/s transmission systems are optimized for a wide range of transmission fiber and DCF input powers. The simulation results for SMF, NZDSFHD, NZDSFLD fiber types and for NRZ, RZ, CSRZ and CSRZ-DPSK modulation formats are presented. CSRZ-DPSK modulation, balanced receiver (Bal-Rx) and NZDSFHD transmission fiber combination found to be superior to others, giving 880 km system reach with Q > 6. The alternating dispersion compensation is then applied and optimized for various modulation format and fiber types. This simple dispersion management technique provided significant system reach extension of 60% when CSRZ-DPSK modulation, Bal-Rx and SMF transmission fiber combination is used.

Field trials with channel bit rates of 160 Gbit/s

We present two 8/spl times/170 Gbit/s DWDM/OTDM (1.28 Tbit/s) field transmission experiment both over more than 400 km in commercially operated legacy networks of France Telecom (FT) and Deutsche Telekom (DT), respectively. Conventional EDFA based amplification schemes as well as distributed Raman amplified systems are tested. For different levels of polarization mode dispersion due to different quality of the installed fibre infrastructure adaptive PMD compensation and polarization de-multiplexing is tested.

Field transmission of 8/spl times/170 Gbit/s over high loss SSMF link using third order distributed Raman amplification

We report transmission of 1/spl times/170 Gbit/s over 61 dB and 8/spl times/170 Gbit/s over 44 dB attenuating links in the network of a major European network operator. Third order distributed Raman amplification established long span configurations bridging, respectively, 210 km and 165 km repeaterless span.

Design analysis of upgrade strategies from single- to double- and triple-wavelength-band WDM transmission

To meet the demand for ever-increasing transmission capacity led by the increase in Internet traffic, up to 10 Tb/s transmission capacity experiments have been demonstrated using wavelength division multiplexing (WDM) and up to three transmission bands. Most of today’s commercial WDM systems, however, are capable of 80 channels at 10 Gbit/s in the C-band and similar capacity in the L-band. 40 Gbit/s channel rate WDM systems are not yet widely commercially deployed. To achieve the aforementioned multi-terabit capacity systems for the future high spectral efficiency and the opening of additional transmission wavelength bands will be necessary. Besides the already used conventional C-band and the long-wavelength L-band the short wavelength S-band is the most promising candidate for a third transmission window. A key technology for accessing a new transmission band is the availability of optical amplifiers, which is fulfilled for the S-band by using either gain-shifted thulium doped fiber amplifiers or new erbium doped fiber amplifiers. In this paper we will provide an overview of amplifier types and their possible usage to upgrade to multi-band transmission as well as we will discuss general design options for upgrading transmission bands. In particular, we will show numerical results for Raman based C- and L-band amplification with multiple Raman pumps and different pumping schemes and an experiment for opening up the S-band by a fiber amplifier approach.

Tolerances and engineering rules for ultrahigh-speed transmission systems

The increasing demand for high capacity optical networks and the decreasing revenues per bit, combined with the given economy of scale for optical networks, forces the network operators to enhance the channel data rates as well as the channel numbers. Higher channel data rates result in a lower footprint, energy consumption and a lower complexity in network management and operation support systems, due to lower channel numbers. The enhancement of channel data rate in principle leads to a system tolerance reduction for chromatic dispersion, PMD and nonlinear effects. Furthermore higher order effects like dispersion slope and higher order polarization mode dispersion have to be taken into account. On the other hand the fast pulse broadening leads to a quasi linear behaviour of the systems, which relaxed some link design rules compared to 40 Gbit/s transmission. The lower tolerances can partially be mitigated by the implementation of more complex amplification schemes and compensators. The complexity of system design, accounting for less tolerances and adaptive compensating modules, is increased. We investigate theoretically and numerically the limiting physical effects and the impact on the signal performance, induced by chromatic dispersion, PMD and nonlinear impairments. We present derived engineering rules for all relevant effects and for various fiber types, based on channel data rates of 160 Gbit/s. These engineering rules enable design engineers to perform a fast system design and system degradation estimation, without time consuming full numerical simulations.

Tolerances and engineering rules for performance estimation and system design in 160-Gbit/s transmission systems

Increasing demand for high transmission capacity and the decreasing revenues per bit, combined with the given economy of scale for optical networks, forces the network operators to enhance the channel data rates as well as the channel numbers. Higher channel data rates result in a lower footprint, energy consumption and a lower complexity in network management and operation support systems, due to lower channel numbers. In principle the enhancement of channel data rate leads to a reduction of system tolerance for chromatic dispersion, PMD and nonlinear effects. Furthermore higher order effects like dispersion slope and higher order polarization mode dispersion have to be taken into account. On the other hand the fast pulse broadening leads to a quasi linear behaviour of the systems, which relaxes the impact of fiber nonlinearities compared to 40 Gbit/s transmission. The lower tolerances can partially be mitigated by the implementation of compensators and more complex amplification schemes. Accounting for less tolerances, adaptive compensating modules and higher sophisticated amplification schemes, the complexity of system design is increased. We investigate theoretically and numerically the limiting physical effects and the impact on the signal performance, induced by chromatic dispersion and nonlinear impairments. We present derived engineering rules for all relevant effects and for various fiber types, based on channel data rates of 160 Gbit/s. These engineering rules enable design engineers to perform a fast system design and system degradation estimation, without time consuming full numerical simulations.

Transport Solutions for Optically Amplified Networks

Publisher Summary In recent years, the distinction between the system reach of metro and long-haul systems has diminished. Todays metro systems can be easily extended to cover distances longer than 500 km. This development has profound impact on the architecture of the European national networks, where the size of networks is closer to that of current metro/regional networks. Moreover, since signal wavelengths can be extended to distances nearing 100 km without re-amplification, the requirement of a large number of central offices in the legacy national networks in countries like Germany has also diminished. It is therefore more cost effective to consider network architectures with fewer central offices, potentially eliminating up to 90% of the existing ones. Cost benefits will also be derived from the implementation of new technologies such as new modulation formats and coherent detection, particularly for high-data-rate channels. In this chapter, network architecture issues and physical impairments due to chromatic dispersion, polarization mode dispersion (PMD), and related mitigation techniques for these networks are described from the point of view of a European network operator. Simulation results are also presented to show a comparison of the system reach over different types of fiber for signals with return to zero (RZ) and carrier suppressed RZ (CSRZ) modulation formats and the use of Raman and EDFA hybrid amplifiers to optimize the network design.