Coherent transmission is turning optical modules into an electronics game, as evidenced by two announcements coming out this weekend as ECOC 2012 opens in Amsterdam.

Acacia is announcing that 500 of its AC100 modules for 100Gbit/s have been installed in networks as of June. Meanwhile, Clariphy, which sells chips rather than full modules, is pushing more 40 and is undaunted about its prospects for 100Gbit/s.

Both companies are betting on the increased importance of electronics in coherent transport. Digital signal processing is applied on the receiving side, making the signal clean enough to be interpreted.

Acacia's announcement is the first that explains the company's business, although CEO Raj Shanmugaraj basically spilled the beans at the OSA Executive Forum in March. Acacai says the AC100 was the first merchant (that is, not-owned-by-a-systems-company) module to conform to the 100Gbit/s framework defined by the Optical Internetworking Forum (OIF) .

Aside from being the first merchant module on the market, Acacia claims distance as its hallmark. The company says its modules are being used in a 24-spa, 2,500km optical path that runs through nine ROADMs, ostensibly the longest 100Gbit/s path built anywhere so far.

One key to Acacia getting to market was that it enlisted customers, with signed contracts, before the product was even ready. There were caveats, of course; customers could back out if the thing didn't work. The key was that systems companies bought into Acacia's idea.

"None of the traditional module vendors had in-house ASIC expertise," says Benny Mikkelsen, an Acacia founder and its CTO. "We saw that as a great opportunity to come at the module from an ASIC point of view."

The chip side
ClariPhy has been patiently chipping away at the 40Gbit/s market, with a 100Gbit/s product not due until next year.

That won't be too late for its customers, which include module vendors JDSU, NEC and Oclaro, to compete with Acacia, says Paul Voois, ClariPhy's chief strategy officer. "We plan to leapfrog the first generation of 100Gbit/s technology. We'll be coming out with more advanced CMOS technology and better power consumption."

ClariPhy's customers are managing to find other ways into the 100Gbit/s market. Oclaro just announced its own 100Gbit/s line-side module, for example. (See Oclaro Lines Up Against Finisar, JDSU.)

At ECOC on Monday, ClariPhy is announcing a version of its 40Gbit/s ASIC targeted at the metro market, rather than long-haul. The key is that it's beefed up the forward error correction (FEC) compared with the long-haul version of its 40Gbit/s chip. That would give signals a better chance of surviving interference from neighboring 10Gbit/s wavelengths -- a likely scenario in a metro environment.

ClariPhy's metro 40Gbit/s chip is in trials with Tier 1 OEMs, Voois says.

Acacia, meanwhile, has its eye on the metro. Next steps for the company would include 100Gbit/s metro products, as well as modules with adaptive rates and distances, Shanmugaraj says.

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— Craig Matsumoto, Managing Editor, Light Reading