S. Spälter

Reduction of Gordon-Mollenauer phase noise by midlink spectral inversion

We show that spectral inversion can be employed for regeneration to reduce the effect of phase noise (Gordon-Mollenauer phase noise) in a nonreturn-to-zero differential phase-shift-keying based transmission system. Several locations of the spectral inverter in an eight-span transmission link have been investigated. We show that the best results are obtained when the spectral inverter is placed in the middle of the link. Compared to the transmission system without spectral inverter, an improvement of over four decades in bit-error-rate performance is achieved.

16/spl times/40 gb/s over 800 km of SSMF using mid-link spectral inversion

We demonstrate the feasibility of a cost-effective 640 Gb/s (16/spl times/40 Gb/s) wavelength-division-multiplexed (WDM) transmission system over 800 km of conventional standard single-mode fiber (SSMF) without using in-line dispersion management. Instead for chromatic-dispersion compensation, a Magnesium-oxide-doped periodically poled lithium niobate (MgO : PPLN)-based polarization-diverse subsystem is used to phase conjugate all 16 channels. The transmission line uses all erbium-doped fiber amplifiers and has an amplifier spacing of 100 km. All channels launched were copolarized. To the best of our knowledge, this is the first WDM transmission experiment with a channel data rate of 40 Gb/s using a PPLN as chromatic-dispersion compensator.

Reduction of phase noise by mid-link spectral inversion in a DPSK based transmission system

We show, in an 800 km SSMF (standard single mode fiber) transmission experiment, that mid-link spectral inversion can be employed to reduce the effect of phase noise (Gordon-Mollenauer noise) on DPSK (differential phase-shift-keying) by over two decades in BER.

10,200 km 22/spl times/2/spl times/10 Gbit/s RZ-DQPSK dense WDM transmission without inline dispersion compensation through optical phase conjugation

Using optical phase conjugation with a polarization independent periodically-poled lithium-niobate subsystem, we demonstrate dense WDM 2/spl times/10 Gbit/s RZ-DQPSK transmission over 10,200 km of SSMF with a record accumulated dispersion exceeding 80,000 ps/nm.

Mixed data rate and format transmission (40-Gbit/s non-return-to-zero, 40-Gbit/s duobinary, and 10-Gbit/s non-return-to-zero) by mid-link spectral inversion

A polarization-diverse subsystem based on periodically poled lithium niobate waveguides is used as an optical phase conjugator for compensation for linear and nonlinear distortion. We show successful transmission formats of 13 x 40 Gbit/s non-return-to-zero mixed with 6 x 10 Gbit/s non-return-to-zero and 40-Gbit/s duobinary over 8 x 100 km of standard single-mode fiber. A single phase conjugator is used to conjugate all data formats, including the alternative duobinary format, simultaneously.

Phase conjugation for increased system robustness

The transmission performance of optical phase conjugation (OPC) is assessed with a special focus on the combination with the RZ-DQPSK modulation format. We show that when OPC is employed, significant performance improvement is obtained compared to conventional DCF based transmission.

Experimental verification of fast analytical models for XPM-impaired mixed-fiber transparent optical networks

The impact of cross-phase modulation on 10-Gb/s nonreturn-to-zero 50-GHz spaced transparent optical networks employing mixed-fibers is investigated. The measured impairments verified our analytical model and are compared to systems with standard single-mode fiber or nonzero dispersion-shifted fiber only.

Optimizing the wavelength configuration for FWM-based demultiplexing in a SOA

In this paper efficient FWM demultiplexing in a SOA using a well chosen wavelength configuration is presented. A 160-Gbit/s OTDM signal is demultiplexed error-free to a base rate as high as 40 Gbit/s.

Comparative assessment of network architectures for transporting packet and TDM traffic

Advancement of communication technologies and business patterns has contributed to the increase of consumer demand and machine-to-machine network traffic. Following this, a steep downward trend in revenue per bit and a slower decay in cost per bit transported is being observed. This poses serious challenge for network operators to correctly choose the technologies and architecture for transporting both packet and legacy TDM traffic. Thus, future expansion of the network should exploit the architecture that results in the most cost-effective transport of both packet and TDM traffic, aiming to keep TCO at its lowest while ensuring traffic meets its designated SLAs. In this paper we address metro, regional and long haul networks with varying traffic patterns (both packet and TDM) looking at the fundamental problems in network scalability and point to some solutions to ensure that cost-effective network traffic scaling can continue to enable future communications services.

Experimental verification of fast analytical models for four-wave mixing (FWM)-impaired transparent optical networks

In this paper four-wave mixing (FWM) and its impact on multi-span NRZ-modulated wavelength division multiplexing (WDM) systems are examined. The impact of the inline dispersion compensation map on FWM impairments is crucial. From re-circulating loop experiments as well as our analytical model worst-case conditions for the dispersion map are found. Furthermore, the impact of increasing the number of WDM channels is investigated. An analytical model is presented to assess the signal degradation. The impairments due to FWM are related to a Q-factor or an EOP. The presented formulas are applied to different dispersion compensation schemes and also mixed-fiber systems. The analytical model is verified by system simulations employing the split-step Fourier method as well as re-circulating loop experiments.