Dmitriy Kovsh

First dispersion-flattened transpacific undersea system: from design to terabit/s field trial

The 8991-km-long transpacific segment of the Tyco Global Network (TGN) [TGN is a trademark of Tyco Telecommunications, Eatontown, NJ 07724 USA], connecting Hillsboro, Oregon, USA to Toyohashi, Japan, is the first installed dispersion-flattened dense wavelength division multiplexed (DWDM) system. In this paper, we describe the development path bringing this system from the computer design stage to a field trial, which confirms that the installed segment can support the design capacity of 96/spl times/10 Gb/s customer channels per fiber pair. Commercial channels have been provisioned on this segment with satisfactory system margins. Exploratory transmission results at 128/spl times/12.3 Gb/s over this segment are also reported here. The experimental results agree well with our expectations based on the results from our system design simulator.

Enhancement in performance of long-haul DWDM systems via optimization of the transmission format

We have numerically investigated transmission properties of four transmission formats. We established that while conventional WDM systems with large channel spacing benefit from shorter RZ and CRZ pulses that help to cope with nonlinearity, the newer generation of DWDM systems with spectral efficiencies greater than 40% will need pulses with narrower spectrum to fight the channel crosstalk. We showed that a good candidate for use in such system is a long duty cycle RZ format. Its spectrum at the receiver is nearly as narrow as the one of NRZ format but the transmission properties are better. We found that by optimizing the pulse width (duty cycle) of RZ pulses we can match the performance of CRZ signal in the system with the large channel spacing (50 GHz) and show better performance than the one of NRZ or CSRZ signal for system with tight channel spacing (25 GHz).

Reducing interchannel crosstalk in long-haul DWDM systems

Nonlinear interaction between signal channels may result in significant performance degradation in transoceanic dense wavelength-division-multiplexing (WDM) transmission systems operated at high bit rates. In this paper, we report that the nonlinear crosstalk for systems with high spectral efficiency can be suppressed if WDM channels are launched with orthogonal relative states of polarization. It is shown that for adjacent channels (that experience the strongest nonlinear interaction) the launched relative state of polarization is maintained over the large distance of low polarization-mode dispersion fiber typically used in undersea systems. Numerical studies, as well as experimental results, are presented for standard and dispersion slope-matched dispersion maps.

Modeling RZ-DPSK transmission - simulations and measurements for an installed submarine system

We model RZ-DPSK transmission in an installed 6,550 km transatlantic submarine system. Simulations agree well with measurements. Simulations predict that nonlinear noise does not eliminate the RZ-DPSK advantage over RZ-OOK, even for trans-Pacific distances.

Terabit/s field trial over the first installed dispersion-flattened transpacific system

We present results of a successful field trial at 96 /spl times/ 12.3 Gb/s per fiber over the first installed dispersion-flattened transpacific system, 8991-km long, part of the Tyco Global Network/sup /spl trade//, plus experimental results for 128 /spl times/ 12.3 Gb/s over the same path.

Optical test equipment for performance evaluation of installed DWDM systems

We have developed a TOTE/spl trade/ technique for evaluation of the full capacity performance of DWDM systems without need for full terminal equipment. The presented TOTE/spl trade/ design works independently of the system bandwidth and channel spacing and is thus very attractive for performance evaluation of installed DWDM systems. In a 28 nm, transatlantic DWDM field transmission experiment, the presented TOTE/spl trade/ design is verified to accurately measure the same gain shape and performance as the fully loaded transmitter.

Spectral hole burning simulation and experimental verification in long-haul WDM systems

The effect of spectral hole burning on long-haul WDM systems was simulated and measured on installed transatlantic link. Changes in end-to-end system gain versus number and wavelength of channels were evaluated. Modeling results are in good agreement with experimental data.

Long-Haul Raman-Assisted EDFA Systems with Ultra-Long Spans

We present a methodology to optimize a Raman assisted EDFA transmission system. We analyzed span lengths from 120 km to 210 km and then give in-depth numerical and experimental results for 150 km spans.

Advanced Repeater Architectures with Ultra-Long Spans for Submarine Systems

We present a comparative analysis of two remotely pumped amplifiers schemes used for long-haul transmission. Our numerical and experimental studies show that the remotely pumped EDFA scheme is superior to the Raman assisted EDFA system.

Modeling 40 Gb/s CSRZ-DPSK and RZ-DPSK trans-Atlantic transmission with dispersion slope compensation

We model a 40 Gb/s RZ and CSRZ-DPSK transmission over a trans-Atlantic system using non-slope-matched fiber with dispersion slope compensation. Slope compensation is necessary to achieve reasonable margins.