Microphotonics-based servers extend test facilities

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Developers and manufacturers of fiber-optic technologies must ensure their products meet or exceed critical design criteria. These companies employ quality assurance or design verification testing teams to put not-yet-released products through a broad range of rigorous tests to identify and repair functional and performance errors. Likewise, to ensure quality control, manufacturers test each of their newly fabricated optical components and systems, often including numerous parametric measurements such as jitter, optical power levels, extinction ratios, and bit-error rates.Th 144561

A fiber-connection server houses input and output fibers connected to a fiber patch panel so fibers can be connected from the server to test equipment and devices under test. Once connected, the system's microphotonics technology enables test engineers to reconfigure physical layer fiber connections via a Web control interface, which enables multiple test teams to share the same test equipment.

The instruments necessary to make such measurements are highly sophisticated and expensive, often exceeding $100,000 for a single device and millions of dollars for a lab configured with dozens of devices. Developers and manufacturers could consume their entire capital budget to keep up-to-date test equipment on hand. Many optical equipment suppliers have test teams located in separate buildings—across a corporate campus and around the globe—which means they must purchase and maintain this expensive equipment for numerous facilities. That results in poor capital-resource utilization because the test instruments remain idle for much of the time. Nonetheless, when engineers need to make critical measurements, the equipment must be readily available wherever the measurements are made.

Microphotonics-based fiber-connection servers establish physical layer (PHY) transparent connections. Thus, these systems can physically insert optical measurement instruments at any point in a network (even between network elements) to measure the optical performance of any port. Users can program these servers to execute and record measurements automatically, operating nonstop around the clock. As a result, companies that choose to employ teams of technicians to frequently patch and repatch fiber connections are at a significant competitive disadvantage compared with those using fiber-connection servers.

Test teams strive to execute a broad range of tests to validate a product's ability to operate in a variety of network topologies as well as in real-world network scenarios such as with older versions of products, third-party products, network outages, cut fibers, and heavy traffic loads. Quality assurance teams frequently reconfigure their test networks into repeatable topologies to execute regression tests. Manufacturing personnel must execute a sequence of tests from among several kinds of optical measurement equipment so their manufacturing lines are as efficient as possible, testing one port after another—nonstop.

In each of these situations, a test team rearranges the physical fiber connections of their test networks. Tracking, maintaining, and reconfiguring all the fiber connections between ports by hand is costly, error-prone, and slow; it can take more than a day for technicians to set up a new test scenario. How can organizations instantly, accurately, predictably, and even automatically reconfigure their physical fiber connections in their test networks to improve their product quality while simultaneously shortening their product introduction schedules?Th 144562

Manufacturing organizations use a fiber-connection server to connect two lines (devices under test) to shared measurement equipment.

At some optical products suppliers, the manufacturing and test organizations have pooled their capital resources to construct centralized first-class optical test facilities. By employing fiber-connection servers, these suppliers have extended the use of their test facilities to multiple teams within their own company, which access these pooled resources via the Internet. Because test personnel reconfigure fiber connections using a Web browser, these companies have avoided the need to purchase, deploy, and maintain million-dollar test facilities in multiple locations. In some cases, test teams have used these pooled resources more frequently, reducing equipment "idle-time" and improving their capital utilization by more than 400%.

Fiber-connection servers are based on microphotonics—silicon-based micro-machined devices used to manage optical signals on fibers—combined with Internet server technology. Suppliers of microphotonics use semiconductor fabrication techniques to achieve scalability and reliability. These devices can efficiently couple light from one fiber to another without signal regeneration (optical-electrical-optical) and support large nonblocking switching elements. In short, microphotonics devices can switch light between input and output fibers to establish PHY transparent connections that maintain the integrity of the signals transmitted by network elements. Transparency also means that microphotonics devices are compatible with any network protocol and data rate, even OC-768 (40 Gbits/sec) and beyond, making this technology a cost-effective investment.

Fiber-connection servers are rack-mountable or desktop products, which can be connected to corporate LANs and accessed locally or remotely via the Internet. These servers generally support a rich control interface, programming capability, Web-based user interfaces, and other features. Such products typically include input and output fibers connected to a fiber patch panel so that fibers can be connected from the server to test equipment and devices under test. Once connected, test engineers can manage PHY fiber connections via a Web control interface instead of by patching fibers together by hand.

In addition to promoting capital efficiencies, fiber-connection servers can help organizations reduce operational expenditures and product development schedules. For example, test engineers can interact with one or more servers to view the connection status of every fiber interface. They can edit connections and save connection maps to standard text files on any client PC. They can also edit fiber connections offline and e-mail connection-map files to remote colleagues to discuss new test scenario—or instantly load such configurations into other fiber-connection servers to establish mirror configurations among two or more test networks. Organizations have reconfigured an entire testbed in minutes instead of days, saving significant personnel costs, reducing test schedules, and improving the quality of their tests and products.

Michael McLaughlin is vice president of corporate development at Glimmerglass (Hayward, CA).

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