Faster data rates push performance
Stephen G. Anderson
Editor in Chief
Optical communications networks are continuing to grow at unprecedented levels as demand for higher data rates pushes both component and systems designers to figure out how to squeeze more optical channels at higher data rates into fiberoptic systems. Deployment of 2.5 Gbit/s channels is now well under way, with 10 Gbit/s hard on its heels, and 40 Gbit/s on the horizon. To meet this increasing demand, channel counts in wavelength division multiplexing (WDM) are being continually pushed to new limits, jumping from 32 to 256 by the end of this year; channel spacing is closer and the channels are operating across a broader wavelength range. As a result of making these systems work harder, individual performance issues take on new dimensions and the importance of effects such as dispersion, crosstalk, and jitter increases significantly.
The development and testing of these systems and their components represents an ongoing challenge to the engineers tasked with making them work and will open new commercial opportunities for all concerned. Simply addressing dispersion compensation, for example, will result in a world market for dispersion compensators that will exceed $435 million by 2009, up from just $37 million in 1999 (see p. 22). On the design front, computer aided design tools are an essential aspect of meeting increasingly stringent component specifications. Such tools help designers to model new components (see p. 41) as well as to simulate their actual performance in a system (see p. 51). Meanwhile, rapid and accurate testing of manufactured components is critical to overall network performance and novel approaches are vital if the rate of infrastructure growth is to be sustained. One method for high-resolution testing of passive optical components, for example, involves in situ swept-wavelength characterization (see p. 63). Yet another concern is network performance monitoring, which also requires novel approaches to deal with the escalating level of sophistication. New methods are being developed to measure these critical parameters simultaneously using real-time optical analysis (see p. 57).
The market evolution that has driven network data rates and channel counts ever upwards also has pushed other key optical technologies to keep in step. Until recently optical amplifiers were not widely seen as cost-effective for short-haul metropolitan networks. But market demand is changing that view as lower-cost designs for in-line devices with add/drop functions emerge (see p. 27). And a novel modular amplifier design approach may offer easy bandwidth expansion with an integrated add/drop filter for networks that need to plan for growth (see p. 33).