Andreas Gerster
Throughout the recent decline of nearly all markets in the high-tech sector, the optical communications market appeared to be hit particularly hard because a dramatic slowdown in the first quarter of 2001 followed hard on the heels of explosive growth in the previous year. The big players in the optical communications market are laying off workers by the thousands, and billions of dollars have been wiped off the stock markets as investors have returned to old-fashioned questions about things such as "profit."
This market setback will affect the manufacturing processes of optical components, and manufacturers will use this break to consolidate and improve their processes to become more cost-effective and gain yield-volume flexibility for the next growth period (see figure). On one hand this strategy will mainly affect mature components in well-established manufacturing and test processes; on the other hand much effort will go into fast-paced technology advancement to generate new business. For next-generation 40-Gbit/s components such as dispersion compensators and optical crossconnects time-to-market has become the key success factor.
In preparation for resumed market growth after the current downturn, optics manufacturers are simplifying and automating assembly and test processes, such as precision optical alignment of a beamsplitter (top) and final assembly of an external laser-cavity module (bottom) for tunable laser sources.
Service providers regroup
One obvious factor in the market slowdown is the fact that service providers saw revenues grow much more slowly than network costs. Today, the direct effect of this is the slow demise of the flat-rate cost models for nonbusiness Internet users as well as the shake-out of many of the new low-cost sevice providers during the past months. As service providers cut their capital expenditures to fund operations, the problem started to ripple down the food chain: network equipment manufacturers, and in turn optical component manufacturers, have had to struggle along with other related industries. Thus all involved in the food chain will have to do their homework to restart business growth.
Service providers will focus on data traffic as a business model in which most of the revenues are generated by voice, and bandwidth demand dominated by data will no longer be viable. In addition, they will pressure network equipment manufacturers to lower operating costs by standardizing equipment and enabling fast (automatic) provisioning with new technologies and network topologies. Network equipment manufacturers will enable new network architectures with intelligent optical networks utilizing technologies such as optical packet switching and multiprotocol lambda switching; standardization will eliminate proprietary vendor solutions. This will ensure interoperability and high reliability, hence reducing costs to carriers and manufacturers.
The component equipment manufacturers in turn will have to support these goals by standardizing manufacturing and test processes for mature (10-Gbit/s) components to bring manufacturing costs down. This means that technology and innovation will be applied to the manufacturing process rather than to the product itself. The second challenge will be the enabling of new network technologies by reducing time-to-market of new components (like optical crossconnects and 40-Gbit/s enabling technologies). These needs will not only drive the manufacturing processes but will also drive the testing of optical components.
Component makers automate
In the coming months, we will see component manufacturers use the changed market situation to revise their manufacturing and test strategies. In the days when the only objective was to satisfy a virtually unlimited demand, "clone and go" was often the method of choice. Instead of spending a lot of engineering effort on process improvement and better efficiency, capacity was increased by adding people to the direct labor workforce and by purchasing new instruments (provided that the supplier was able to deliver). The new trends, as mentioned previously, are to reduce time-to-market for emerging components and to increase manufacturing efficiency for mature products.
Many of the workers that have been laid off will be replaced by automated manufacturing and test processes. This will also allow a very smooth ramp-up once business picks up again. Optical test processes will have to be integrated seamlessly in the manufacturing process to avoid expensive and time-consuming operator-assisted tests. Intelligent test probes integrated into the manufacturing network will replace rack-based test instruments with user interfaces, and the generated test data will be fed directly into the manufacturing-process control system for online quality and throughput control.
To enable a fast test setup, more and more measurement algorithms will be available on the probes, which will dramatically reduce process complexity and the need for user programming. This will be supported by the standardization of test algorithms, test margins and reported parameters. Using the test software provided by the test instrument supplier will also increase yield and throughput (and thus further reduce cost) by offering superior accuracy and measurement speed.
Highly flexible and scalable test systems will enable easy ramp-up and slowdown of different products on the same manufacturing line. This will be achieved by powerful test platforms supporting a large variety of stimulus-and-probe modules; in addition, the probes will scale in form factor to fit automated workcells.
New generation of components
Besides bringing the cost of test down to a few percent during the next years, test-instrument manufacturers will support the development of leading-edge network components along the product life cycle. In the R&D stage, powerful test boxes will become the optical engineer's oscilloscope, enabling him to measure amplitude and phase of a component's transfer function as well as to characterize 40-Gbit/s components. Complex measurements will be at the engineer's fingertips on the test instrument, allowing him or her to focus on the creative job instead of coding measurement functions. Easy data exchange with optical-design software tools will also help to minimize development cycles; in the pilot-line production phase, flexible rack-and-stack solutions will allow the easy setup of manufacturing tests by using the same test algorithms as in R&D.
In this context it is worth taking a closer look at some of the new components for next-generation optical networks. One important enabler is the optical crossconnect, characterized by huge port counts; devices of 1000 x 1000 ports are already out of the labs. The biggest challenge when measuring these devices will be connectivity with the footprint of the related test system. These devices will not be connected manually to test systems in mass production; thus the connectivity process will have to be automated. This will have to be supported by standardization of high-density connectors and a high degree of integration at the test probe.
For instance, instead of using single-port optical-power meters, the engineers will look for sensor arrays offering several tens of detectors per square centimeter at the front panel (the measurement algorithms have to be adapted to huge quantities of measurement data). As there will probably be a need to measure dynamic properties, some sort of synchronization between parameter setting of the test device and measurement of the optical parameters will be necessary.
Additional measurement challenges
In 40-Gbit/s networks dynamic dispersion compensators will prevent data bits from running out of phase along the transmission line. For these devices the measurement of dynamic behavior will also require new test strategies that need to be supported by the instruments.
The overall trend to bring costs down for installing, operating, and configuring optical networks is having a strong influence on the way optical components are manufactured and tested. Enhancements on measurement instruments and automated test equipment will bring manufacturing and test costs down further. And at the same time, new test instruments will help to enable the new generation of optical components that are required for cost-effective network operation and configuration.
ANDREAS GERSTER is the product marketing manager for testing platforms in the Optical Communication Measurement Division of Agilent Technologies GmbH, Herrenberger Str. 130, 71034 Böblingen, Germany. Fax: 49-7031-464-7023; e-mail: [email protected]; www.agilent.com.