Aleksandra Boskovic

Value of reach-and-split ratio increase in FTTH access networks

Comprehensive cost modeling of fiber-to-the-home passive optical network solutions, which includes outside plant, head end, and premises equipment and labor, reveals the potential of 4%-5% savings per subscriber (

10-Gb/s transmission of 1.55-μm directly modulated signal over 100 km of negative dispersion fiber

100-

Effects of filter concatenation for directly modulated transmission lasers at 2.5 and 10 Gb/s

140) for networks with enhanced reach-and-split ratio compared with equipment available today.

Performance engineering and topological design of metro WDM optical networks using computer simulation

In this letter, the largest transmission distance (100 km) ever reported for a commercially available 10-Gb/s 1.55-/spl mu/m directly modulated signal over a single fiber link without using any dispersion compensation is demonstrated. The achieved dispersion-length product for a Q-factor greater than 9.4 dB (bit-error rate less than 10/sup -15/) was about 750 ps/nm. The fiber that enabled such long transmission distance with high dispersion tolerance is a nonzero dispersion-shifted fiber that has negative dispersion in the entire usable bandwidth (1280-1620 nm) and is optimized for operation with directly modulated lasers. The excellent single-channel transmission performance that we achieved can be expected also from wavelength-division-multiplexed systems with channels across the erbium-doped fiber amplifier bands.

Study of the performance of a transparent and reconfigurable metropolitan area network

We report computer simulation results of the effects on optical signal quality of passage through a cascade of wavelength division multiplexing (WDM) filters-multiplexers and demultiplexers-for directly modulated lasers with different chirp characteristics. In particular, lasers with transient or adiabatic chirp characteristics at 2.5 Gb/s and 10 Gb/s are investigated, and we find clear differences between the laser types with respect to filter concatenation effects. Filters with an optical bandwidth suitable for a 200-GHz channel-spacing system are considered, and we evaluate the system behavior as a function of laser frequency offset for a fixed number of filters. The reference network architecture used for the simulations is an optically transparent metropolitan scale network in which the WDM signals may be demultiplexed and then multiplexed again at multiple optical network elements. The signal quality is evaluated in terms of a distortion-induced eye-closure penalty as well as the excess attenuation or loss suffered. We find that transient chirp-dominated lasers show a generally symmetric distortion penalty response to laser frequency offset, whereas the response for adiabatic chirp dominated lasers is highly asymmetric. Furthermore, the extinction ratio for the latter class of lasers can be improved, in some cases, by the appropriate offset between laser and filter center frequencies.

Extraction of laser rate equations parameters for representative simulations of metropolitan-area transmission systems and networks

This paper demonstrates the use of computer simulation for topological design and performance engineering of transparent wavelength-division multiplexing metropolitan-area networks. Engineering of these networks involves the study of various transport-layer impairments such as amplifier noise, component ripple, chirp/dispersion, optical crosstalk, waveform distortion due to filter concatenation, fiber nonlinearities, and polarization effects. A computer simulation methodology composed of three main simulation steps is derived and implemented. This methodology obtains performance estimations by applying efficient wavelength-domain simulations on the entire network topology, followed by time-/frequency-domain simulations on selected paths of the network and finally Q-budgeting on an identified worst case path. The above technique provides an efficient tool for topological design and network performance engineering. Accurate simulation models are presented for each of the performance impairments, and the computer simulation methodology is used for the design and engineering of a number of actual metro network architectures.

Metro network utilizing 10 Gb/s directly modulated lasers and negative dispersion fiber

The transport performance of an optically transparent regional-size ring network testbed with circumference of 280 km, based on metro-area optimized optical layer components and fiber, is demonstrated under dynamic traffic conditions. For the longest transmission path, excellent transmission performance is achieved using cost-effective directly modulated signals. Network reconfigurability is achieved using add-drop modules that are commercially available as of this writing. We show that the dynamic nature of the network does not affect the system performance. In particular, we show that electronic gain control of erbium-doped amplifiers is capable of managing switching transients in amplified metro-scale networks.

FWM penalty reduction in dense WDM systems through channel detuning

Abstract In this paper we present procedures for the extraction of laser rate equation parameters. The parameters are extracted using fitting of static and dynamic measurements with simple theoretical expressions. In particular, chirp related parameters are extracted directly through measured chirp and power waveforms. The extracted parameters are used in a large-signal rate equation laser model to calculate the power and chirp waveforms. The simulations are compared with experiments and the agreement is excellent. The procedures have been applied to directly modulated lasers having different chirp characteristics and designed for either 2.5 or 10 Gb/s operation. Using the rate equation laser model with the extracted parameters, we performed a simulation study to identify the value of employing a negative dispersion fiber in metro-area networks. It is shown that dispersion shifted fibers with negative dispersion across the entire usable fiber bandwidth (1280–1620 nm) advances the performance of directly modulated lasers used in wavelength division multiplexed metropolitan-area transmission systems and networks. At 2.5 Gb/s transmission over 300 km of negative dispersion fibers is possible for directly modulated lasers across the erbium doped fiber amplifier bandwidth, while at 10 Gb/s an impressive distance of 100 km can be achieved.

Transport performance of an 80-Gb/s WDM regional area transparent ring network utilizing directly modulated lasers

In this letter, we present the feasibility of metro area transparent wavelength-division-multiplexing networking with cost-effective 1550 nm 10 Gb/s directly modulated transmitters. We report excellent performance results (Q-factor>9 dB) for a transparent short-reach metropolitan area ring network based on application-optimized, optical layer components and fiber. The demonstration is based on a network consisting of four nodes interconnected with 25.5 km spans of uncompensated negative dispersion fiber. The network is designed to support 32 directly modulated channels operating at 10 Gb/s (320 Gb/s capacity).

PDL-induced channel power divergence in a metro WDM network

The impact of four wave mixing (FWM) as a function of the channel alignment is studied. A channel plan is proposed which minimizes FWM penalties while still agreeing with the ITU grid. We have shown that in order to demonstrate system performance under the effect of FWM it is necessary to control the alignment of the WDM channels with an accuracy significantly better than the bandwidth of the RX.