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Kotura taps CMOS foundry for 100G photonics chips

Posted: 29 Jan 2013 ?? ?Print Version ?Bookmark and Share

Keywords:CMOS foundry? silicon photonics? optical fibre? VCSELs? wavelength division multiplexing?

A "large CMOS foundry" will make 100G silicon photonics chips for Kotura that will sample later this year, facing competition from Cisco, Intel and Luxtera.

Silicon photronics provider Kotura is a few weeks away from unveiling its partnership with "a large CMOS foundry" that will make its chips. The news is one more sign that companies like Cisco, Intel and Luxtera aim to ship the technology in 2014 as a disruptive, lower cost alternative to today's 100 Gbit/second optics.

Arlon Martin, Kotura's vice president of marketing, contracts and government affairs, stated that the company is "in the early stages of the R&D process" with the unnamed foundry. He also stated that there's been a lot of work in the background, but we are not ready until late 2013 to sample product from them.

The privately-held company employs about 80 people and shipped its first silicon photonics chip in 2006. Since then sales have grown to about 100,000 units a year made in its modest facility.

Kotura hopes to be in production in 2014 with a 4x5 mm module that pumps 100 Gbit/s over one optical fibre. It will consume about 3.5W and, thanks to its use of single-mode fibre, it can theoretically deliver distances of 20m to 2km.

The product uses four external lasers!its only optical components!modulating four 25 Gbit/s signals on to a single fibre with wavelength division multiplexing (WDM). The module also contains a third-party CMOS driver. Kotura's CMOS chip, made in a 200nm process, uses some germanium for its light detector function.

Martin said the product could start selling for less than $1,000 in volumes and eventually decline to about $100. That compares with some estimates of as much as $100,000 per port for 100G Ethernet today and about $250 for 40G.

"Our fab is fine for volumes we are doing in telecom and great for us to get started, but a commercial fab lets us ramp" Martin said.

Intel, Luxtera hot on the trail
Indeed, a handful of companies including Cisco Systems, Intel, Luxtera!and maybe IBM!hope to ramp some sort of silicon photonics offering in 2014, mainly targeting 100G opportunities.

"There is a huge bottleneck at 100G out there," said Martin. "The old style optics are clumsy, big and expensive, but with silicon photonics you integrates all that stuff!hundreds of piece parts!into a single chip."

Intel showed in 2010 a prototype using a similar approach to Kotura, multiplexing four signals with WDM over a single fibre. But the x86 giant spiked interest in the area last week when it announced engineering samples for a 100G product using four parallel fibres carrying 25G signals. (see

Justin Rattner, Intel's chief technology officer, and Arista Networks founder Andy Bechtolsheim said the 100G modules will be a huge enabler for all sorts of uses inside and between server racks in a data centre.

Like Intel, start-up Luxtera is preparing a 100G module using four 25G fibres. It says its products could cost as little as $250 for distances of less than two meters. The product will consume about 2.5W even if clock-data recovery circuits are required, said Chris Bergey, vice president of marketing for Luxtera.

Luxtera considers itself ahead because it has already shipped more than half a million 56G silicon photonics chip sets for use with Infiniband. It is waiting for ASICs with 25G serdes to ship in 2014 before it rolls out its 100G product, said Bergey.

Work on 25G chip-to-chip interconnects is expected to be one of the hot topics at DesignCon.

Luxtera got $21.7 million in a C round of venture funding in February 2012, including investment from Broadcom. It struck a deal that same month with STMicroelectronics to make its devices in a 300mm Crolles, France, fab.

The start-up uses a single external laser to save cost. It claims all other functions are handled on its chip which uses MEMS techniques.

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