Some vendors say they are going beyond the plain bit-error-rate testers and other discrete equipment in a bid to develop boxes specifically for the optical industry, in some instances hoping to tailor systems to nonoptics experts.

Circadiant Systems Inc. (Allentown, Pa.), which was founded on just that principle, aimed to build a specialty optical tester from scratch in hopes of producing a more compact box. At OFC here, the company launched the A3306, a tester for 10-Gbit/second traffic, including Sonet and Ethernet.

Circadiant was founded by engineers who have had to do optical test before, said Paul Fitzgerald, vice president of marketing. While modular test equipment was available, it came in bulky, rack-mounted boxes. Circadiant's other goal was to automate optical testing, because engineers called upon for test aren't always optical experts.

"It never occurred to anyone" to make a compact, automated tester, Fitzgerald said. "The thought was, 'Let's make lots of different modules that customers can put into a rack.' What that leaves out is the automation, because the test equipment doesn't understand how the optical tests are really being done."

The A3306, a follow-up to a previous 2.5-Gbit/s tester, automates common optical tests for parameters such as path sensitivity, which judges how well transmissions can be received if the light level is low. Beyond testing physical parameters, the Circadiant boxes can test Layer 2 and 3 traffic by setting up Ethernet or packet-over-Sonet sessions.

The optical test market is also attracting test companies from the electronics sector. Wavecrest (Eden Prairie, Minn.), a veteran at jitter testing in the electrical domain, has moved into the optical realm, announcing at OFC the OE-2 optical-to-electrical converter. The OE-2 plugs into the company's existing SIA-3000 electrical tester to provide an optical jitter tester that provides results more quickly than conventional equipment, said John Perlick, director of marketing for Wavecrest's optical division.

Optical test is a new domain for the 17-year-old company, but roughly half of the SIA-3000's customers will require the OE-2 as well, Perlick said.

Normally, jitter can be calculated from bit-error-rate information, but that can take 10 to 60 minutes, Perlick said. The SIA-3000 measures jitter directly by looking at the movement of the rising edges of the bit stream, using a patented algorithm to derive the random and deterministic components of jitter within seconds.

From a business standpoint, Wavecrest officials say theirs is a "blocking" patent, so that the algorithms can't be used elsewhere. "You could use that approach with an oscillator or something like that, but we hold a patent on it," Perlick said.

The SIA-3000, which began shipping on Oct. 31, is a follow-up to several other electrical testers sold by Wavecrest. Unlike other testers, the box doesn't need to know the data rate ahead of time, Perlick said.

Tailored entry

In part, the SIA-3000 is tailored for Wavecrest's entry into optical test. Unlike previous Wavecrest boxes, the system is modular, allowing for add-ons such as the OE-2. In addition, the SIA-3000 can do multichannel testing, a feature added for customers who want to do production testing as opposed to laboratory testing, said Keith Clayton, Wavecrest's vice president of marketing.

The OE-2 is due to begin shipping shortly after OFC.

Another company trying a new spin on existing products was Gnubi Communications (Dallas), which showed a portable version of its EPX family of Sonet bit-error-rate testers. Dubbed TransPort, the portable system weighs roughly 20 pounds and was designed for lab personnel who found themselves having to test field installations of equipment, something that happens frequently, said Gnubi's chief technology officer Gary Mading.

Still other companies presented new directions in optical test. Proximion Fiber Optics AB (Kista, Sweden) demonstrated its Wistom platform, which company officials said is a breakthrough in the area of optical monitoring.

Optical channel monitors are fast, making them useful for detecting fiber breaks and notifying Sonet to shift to its protection lines. But they don't have the resolution that's required as dense wave-division multiplexing systems approach 25-GHz spacing between wavelengths. Optical performance monitors do have that resolution, but they use mechanical mechanisms for scanning the spectrum of wavelengths, making the process too slow for protection.

"Admittedly, there can be some applications where you only need accuracy or protection switching, but as networks evolve, service providers will tell you they need both features. And the only way to do this is to buy two boxes," said Adel Asseh, Proximion's vice president of business development.

Wistom uses tunable fiber Bragg gratings. An acoustic pulse applied to the gratings causes them to receive a particular frequency, and by changing the current, the box scans the spectrum wavelength by wavelength. Wistom can scan 128 channels across the entire C band of wavelengths in less than 100 microseconds, which Proximion claims is faster than any other monitoring device.

Wistom is available as a standalone system or as a card for inclusion in other systems. Both products are sampling now.