William T. Anderson

Consistency of measurement methods for the mode field results in a single-mode fiber

The fields in the core, the far-field radiation pattern, and the transmission through an offset splice for single-mode fibers all are well approximated by Gaussian functions. However, the method used to fit the Gaussian function to measured data influences the resulting width of the Gaussian, which is called the mode field radius. Of the fitting methods studied, only maximization of the launch efficiency integral gives values of mode field radii which are consistent between near-field and far-field measurement methods. The transverse offset measurement method is consistent with these two if an unweighted truncated fit is used. Also. two published analytical formulas for the mode field radius are studied, and only one of the two gives accurate values. A third analytical formula, which is simpler and more accurate over a smaller range of wavelengths, is presented.

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.

Length dependence of the effective cutoff wavelength in single-mode fibers

The effective cutoff wavelength of a depressed cladding single-mode fiber in either a cabled or a loose state depends upon the length of the fiber. This dependence can be accurately represented by a linear function of the logarithm of the fiber length for lengths between 1 m and 1 km. Cutoff will shift 55-66 nm per decade length for slightly and moderately depressed cladding designs, respectively. Neglecting all sources of differential mode attenuation except leaky-mode loss, the computed behavior of cutoff as a function of fiber length agrees reasonably well with the observed behavior for a moderately depressed cladding design. On the other hand, agreement is poor for a slightly depressed cladding design. A knowledge of the length dependence of cutoff is essential for establishing a production requirement for cutoff based upon the needs of the system.

Transmission of 40-Gb/s WDM signals over transoceanic distance using conventional NZ-DSF with receiver dispersion slope compensation

This paper investigated the impact of receiver dispersion slope compensation for 40-Gb/s transoceanic transmission over conventional nonzero dispersion shifted fibers. Various differential phase-shift keying (DPSK) modulation formats were experimentally compared at 42.8 Gb/s [to account for forwarded error correction (FEC) overhead] with dispersion slope compensators at the receiver. These transmission measurements were performed in a circulating loop over a transatlantic distance of 6250 km using a variety of channel spacings, relative polarizations, and synchronous modulation techniques. All formats benefited from receiver dispersion slope compensation. For orthogonally polarized channels on 133-GHz spacing, the return-to-zero DPSK (RZ-DPSK) format performed the best; all channels (18 /spl times/ 40 Gb/s) propagated with > 13.5-dB Q-factor and with > 4-dB FEC margin. Whereas for copolarized channels on 100-GHz spacing, carrier-suppressed return-to-zero (CSRZ)-DPSK performed the best; all channels (25 /spl times/ 40 Gb/s) propagated with > 3-dB FEC margin. Moreover, it was shown that parallel launch only suffered a penalty of /spl sim/ 0.2 and /spl sim/ 0.5 dB relative to the orthogonal launch for 133and 100-GHz channel spacing, respectively. Finally, it was demonstrated that copolarized 40 Gb/s RZ-DPSK worked as well as 10 Gb/s RZ-ON-OFF keying (RZ-OOK) for the same spectral efficiency (30%) over the 6250 km of conventional nonzero dispersion shifted fibers (NZ-DSF) originally designed for 10 Gb/s transmission.

Performance of hybrid multichannel AM/256-QAM video lightwave transmission systems

We report experimental results on the performance of a multichannel hybrid AM/256-QAM video lightwave transmission system. Performance limitations due to impulse noise using a directly-modulated DFB laser transmitter and an externally-modulated YAG laser transmitter are presented. We also compared the BER characteristics of 256-QAM versus 64-QAM signals with either CW carriers or modulated video signals in such a hybrid system. Our results indicate that 64-QAM signal performance is more robust than that of 256-QA as expected. Significant 256-QAM BER degradation is observed with modulated AM-VSB video signals, making it necessary to use forward-error-correction code for robust 256-QAM transmission.<<ETX>>

A New Dispersion Map for Undersea Optical Communication Systems

We present a new type of dispersion map for undersea WDM transmission based on non slope-matched fiber. 64x10 Gb/s were transmitted over transatlantic distance with more than 1.5 dB performance advantage over previous conventional 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.

Long-haul 40 Gb/s RZ-DPSK transmission with long repeater spacing

40 Gb/s RZ-DPSK signals were successfully transmitted over 4,920 km with 110 km repeater spacing using only single stage C-band EDFAs. The performance of 40 Gb/s and 10 Gb/s RZ-DPSK was compared. Q-factor fluctuations are an issue for 40 Gb/s systems.

The MONET project-a final report

The MONET project ends in October 1999 with the completion and operation of a transparent, reconfigurable optical network in Washington, DC. This paper describes the network and summarizes experimental results, achieved in the first months of operation.

Long-Haul 40 Gb/s RZ-DPSK Transmission over 4,450 km with 150-km Repeater Spacing using Raman Assisted EDFAs

40Gb/s RZ-DPSK signals were successfully transmitted over 4450km with 150km repeater spacing (33dB span loss) using Raman assisted EDFAs. The performance was compared with EDFA only amplification and 110km repeater spacing. Long-term Q-factor fluctuations were also quantified for Raman-assisted amplification.