New MSAs target modules and components

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technology

By STEPHEN HARDY

In an environment where standards development can't keep pace with technology advances, multisource agreements (MSAs) provide an alternative. The popularity of these de facto standards has been demonstrated over the past few months with the release of several new agreements. Most focus on transceivers and transponders, but collaborations have also been announced for receivers and semiconductor optical amplifiers (SOAs).Th 93016

While competition looms from XFP and XPAK, XENPAK transceiver developments continue, as this 10GBase-LX4 device from Molex demonstrates. (Photo courtesy of Molex Fiber Optics)

The most radical of these new MSAs is the XFP 10-Gbit Small Form Factor Pluggable (SFP) agreement targeted at applications currently served by MSA-300 transponders and XENPAK transceivers. Promoted by signatories Broadcom, Brocade, Emulex, Finisar, ICS (Sumitomo Electric), JDS Uniphase (JDSU), Maxim, ONI Systems (recently purchased by Ciena), Tyco Electronics, and Velio, the MSA provides an optical module that measures 2.3 inches long, 0.33 inch high, and 0.7 inch wide. The small size derives primarily from removing much of the electronics normally found in optical transponders, with the idea that chip companies will integrate these functions into board-level chips. Broadcom demonstrated such integration at the Optical Fiber Communications (OFC) Conference in March with its BCM8511B DWDM Transport Processor, a device that provides G.709 digital wrapping and forward error correction.

The MSA calls for direct serial connection of the optical module with the onboard electronics. The agreement's XFI serial electrical interface will support serial 10-Gbit/sec board-level transmission to 12 inches, according to Broadcom sources at the show. The MSA allows chip companies to do what they do best: integrate multiplexing/demultiplexing, framing, and other functions into chips, according to Broadcom representatives, who suggested that quad versions of XFP-compliant chips would enable one device to control four optical modules. This approach represents the wave of the future, the Broadcom sources suggested, although some manufacturers of 300-pin transponders contacted at the show strongly disagreed (see "Transponder manufacturers debate electronics," page 35).

The XENPAK MSA took another hit at OFC with the announcement of the XPAK, a module for 10-Gigabit Ethernet (10-GbE) and Fibre Channel applications. Promoted by Infineon Technologies North America, Intel, and Picolight, initial versions of the hot-pluggable devices will use the 10-GbE XAUI electrical interface over a 70-pin RFT-style connector. It will be designed to mount on both sides of a printed circuit board; 20 devices will fit on a 17-inch board, according to the three companies. The MSA envisions 850- and 1310-nm modules, which will support distances of 300 m and 10 km, respectively. A draft version of the XPAK specification was slated to be released in April. For information on the specifications, go to www.xpak.org.

Work continues
Despite the new competition, work on XENPAK offerings continues. Both Agere Systems and Optillion have announced XENPAK modules for 40-km applications. Agere's AE20MRCAA 1310-nm serial device uses uncooled lasers and matches the distances afforded by 1550-nm units. The company will make sample quantities available in the third quarter of this year, with production quantities following in the fourth quarter. Agere expects the transceivers will cost about $2,000 at high production levels. For its part, Optillion's 40-km TOP 5010 uses 1550-nm optics but requires 40% less power than standard XENPAK devices, according to the company. Optillion began sampling the module last month, with broader shipments expected next month.

For shorter distances, Molex has unveiled its MuxLink XENPAK module, which provides WDM transmission in accordance with 10GBase-LX4. The company expected to begin sampling the device last month and is timing volume production to match market demand, which company sources put at the end of this year or the beginning of next year. Molex sources revealed that the company plans to work on a copper-based XENPAK transceiver as well. W.L. Gore & Associates showed such a device at OFC, which it has already begun to sample. Neither company foresees copper supporting transmissions beyond 25 m.

Rounding up recent XENPAK activity, Agilent Technologies announced interoperability of its 1310-nm serial transceiver with XAUI serializer/deserializer devices from PMC-Sierra, Marvell Technology Group, and Texas Instruments. Ignis Optics revealed it plans to ship beta samples of its XENPAK modules next month.

Other agreements
Additional agreements are in the works. Agilent has debuted a hot-pluggable DWDM transceiver that supports multirate (155-Mbit/sec to 2.7-Gbit/sec) operation initially over 160 km, which will form the basis of a new MSA expected this month. Meanwhile, an MSA for a 10-Gbit/sec version of the SFP format is in negotiation as well.

Transceivers and transponders were not the only MSA subjects. Alcatel Optronics, JDSU, and Kamelian inked a pact defining common mechanical and optical performance specifications for SOAs. The MSA defines minimum levels of optical performance required for preamplification and booster applications. Different classes of SOAs are defined for these applications. For preamplification, Class A SOAs will have a noise figure <9 dB, gain >20 dB, and output power of at least 5 dBm. For booster applications, Class B devices with a noise figure <12 dB, gain >15 dB, and output power of 5 dBm minimum will be used.

Receivers also have proven a popular focus for MSAs. For example, Agere and Nortel Networks have joined to promote a surface-mount 10-Gbit/sec receiver design. The positive intrinsic negative (PIN) avalanche photodiode (APD) receivers will come in an 8x10.7x3.3-mm package that conforms to a 17-pin butterfly packaging design with differential radio-frequency output.

The two companies put themselves in competition with NEC Compound Semiconductor Devices and Sumitomo Electric Industries, which announced their own 10-Gbit/sec receiver MSA. The receivers come in a metal ceramic package that measures 9.8x7.5x4 mm. The receivers are designed for 1300-1550-nm applications.

For higher-speed requirements, Fujitsu Quantum Devices, Fujitsu Compound Semiconductor, and JDSU have agreed on an MSA for 40-Gbit/sec PIN receivers with differential co-planar outputs. The receiver design reduces space requirements, cancels common mode noise at the clock and data recovery circuit, and doubles the output voltage swing compared to single-ended designs, according to the MSA signatories. The flange-mount package measures about 24x38x7.4 mm.

In other activity, the two Fujitsu companies have joined with Sumitomo on an MSA for 10-Gbit/sec laser-diode modules. A 1550-nm distributed-feedback diode is integrated with an electro-absoption modulator using a reverse bias-this is integrated with a driver IC.

Meanwhile, Alcatel Optronics, JDSU, and Nortel have launched an MSA that covers 960-980-nm pump lasers in uncooled mini-DIL packaging. They are designed for use in metro and long-haul erbium-doped fiber amplifiers and will offer 100 mW of power over 0-70°C using fiber Bragg grating wavelength locking.

Finally, Emcore, Picolight, and W.L. Gore have joined in an MSA for backplane applications. Called SNAP12, the agreement provides common electrical, mechanical, and optical specifications for connectorized 12-channel parallel optical components that deliver an aggregate of 32 Gbits/sec. The devices use a 100-pin matrix array optical connector and an MPO optical connector.

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