Ciena shops for photonic technology for line-side edge
Part 3: Acquisitions and silicon photonics
Ciena is to acquire the high-speed photonics components division of Teraxion for $32 million. The deal includes 35 employees and Teraxion’s indium phosphide and silicon photonics technologies. The systems vendor is making the acquisition to benefit its coherent-based packet-optical transmission systems in metro and long-haul networks.
Sterling Perrin
“Historically Ciena has been a step ahead of others in introducing new coherent capabilities to the market,” says Ron Kline, principal analyst, intelligent networks at market research company, Ovum. “The technology is critical to own if they want to maintain their edge.”
“Bringing in-house not everything, just piece parts, are becoming differentiators,” says Sterling Perrin, senior analyst at Heavy Reading.
Ciena designs its own WaveLogic coherent DSP-ASICs but buys its optical components. Having its own photonics design team with expertise in indium-phosphide and silicon photonics will allow Ciena to develop complete line-side systems, optimising the photonics and electronics to benefit system performance.
Owning both the photonics and optics also promises to reduce power consumption and improve line-side port density.
“These assets will give us greater control of a critical roadmap component for the advancement of those coherent solutions,” a Ciena spokesperson told Gazettabyte. “These assets will give us greater control of a critical enabling technology to accelerate the pace of our innovation and speed our time-to-market for key packet-optical solutions.”
Ciena have always been do-it-yourself when it comes to optics, and it is an area where they has a huge heritage. So it is an interesting admission that they need somebody else to help them.
The OME 6500 packet optical platform remains a critical system for Ciena in terms of revenues, according to a recent report from the financial analyst firm, Jefferies.
Ciena have always been do-it-yourself when it comes to optics, and it is an area where they have a huge heritage, says Perrin: “So it is an interesting admission that they need somebody else to help them.” It is the silicon photonics technology not just photonic integration that is of importance to Ciena, he says.
Coherent competition
Infinera, which designs its own photonic integrated circuits (PICs) and coherent DSP-ASIC, recently detailed its next-generation coherent toolkit prior to the launch of its terabit PIC and coherent DSP-ASIC. The toolkit uses sub-carriers, parallel processing soft-decision forward-error correction (SD-FEC) and enhanced modulation techniques. These improvements reflect the tighter integration between photonics and electronics for optical transport.
Cisco Systems is another system vendor that develops its own coherent ASICs and has silicon photonics expertise with its Lightwire acquisition in 2012, as does Coriant which works with strategic partners while using merchant coherent processors. Huawei has photonic integration expertise with its acquisitions of indium phosphide UK specialist CIP Technologies in 2012 and Belgian silicon photonics start-up Caliopa in 2013.
Cisco may have started the ball rolling when they acquired silicon photonics start-up Lightwire, and at the time they were criticised for doing so, says Perrin: “This [Ciena move] seems to be partially a response, at least a validation, to what Cisco did, bringing that in-house.”
Optical module maker Acacia also has silicon photonics and DSP-ASIC expertise. Acacia has launched 100 gigabit and 200-400 gigabit CFP optical modules that use silicon photonics.
Companies like Coriant and lots of mid-tier players can use Acacia and rely on the expertise the start-up is driving in photonic integration on the line side, says Perrin. ”Now Ciena wants to own the whole thing which, to me, means they need to move more rapidly, probably driven by the Acacia development.”
Teraxion
Ciena has been working with Canadian firm Teraxion for a long time and the two have a co-development agreement, says Perrin.
Teraxion was founded in 2000 during the optical boom, specialising in dispersion compensation modules and fibre Bragg gratings. In recent years, it has added indium-phosphide and silicon photonics expertise and in 2013 acquired Cogo Optronics, adding indium-phosphide modulator technology.
Teraxion detailed an indium phosphide modulator suited to 400 gigabit at ECOC 2015. Teraxion said at the time that it had demonstrated a 400-gigabit single-wavelength transmission over 500km using polarisation-multiplexed, 16-QAM (PM-16QAM), operating at a symbol rate of 56 gigabaud.
It also has a coherent receiver technology implemented using silicon photonics.
The remaining business of Teraxion covers fibre-optic communication, fibre lasers and optical-sensing applications which employs 120 staff will continue in Québec City.
Teraxion embraces silicon photonics for its products
Teraxion has become a silicon photonics player with the launch of its compact 40 and 100 Gigabit coherent receivers.
The Canadian optical component company has long been known for its fibre Bragg gratings and tunable dispersion compensation products. But for the last three years it has been developing expertise in silicon photonics and at the recent European Conference on Optical Communications (ECOC) exhibition it announced its first products based on the technology.
"You don't have this [fabless] model for indium phosphide or silica, while an ecosystem is developing around silicon photonics"
Martin Guy, Teraxion
"We are playing mainly in the telecom business, which accounts for 80% of our revenues," says Martin Guy, vice president, product management & technology at Teraxion. "It is clear that our customers are going to more integration and smaller form-factors so we need to follow our customers' requirements."
Teraxion assessed several technologies but chose silicon photonics and the fabless model it supports. "We are using all our optical expertise that we can apply to this material but use a process already developed for the CMOS industry, with the [silicon] wafer made externally," says Guy. "You don't have this [fabless] model for indium phosphide or silica, while an ecosystem is developing around silicon photonics."
The company uses hybrid integration for its coherent receiver products, with silicon implementing the passive optical functions to which the active components are coupled. Teraxion is using externally-supplied photo-detectors which are flip-chipped onto the silicon for its coherent receiver.
"We need to use the best material for the function for this high-end product," says Guy. "Our initial goal is not to have everything integrated in silicon."
Coherent receiver
A coherent receiver comprises two inputs - the received optical signal and the local oscillator - and four balanced receiver outputs. Also included in the design are two polarisation beam splitters and two 90-degree hybrid mixers.
Several companies have launched coherent receiver products. These include CyOpyics, Enablence, NEL, NeoPhotonics, Oclaro and u2t Photonics. Silicon photonics player Kotura has also developed the optical functions for a coherent receiver but has not launched a product.
One benefit of using silicon photonics, says Teraxion, is the compact optical designs it enables.
The Optical Internetworking Forum (OIF) has specified a form factor for the 100 Gigabit-per-second (Gbps) coherent receiver. Teraxion has developed a silicon photonics-based product that matches the OIF's form factor sized 40mmx32mm. This is for technology evaluation purposes rather than a commercial product. "If customers want to evaluate our technology, they need to have a compatible footprint with their design," explains Guy. This is available in prototype form and Teraxion has customers ready to evaluate the product.
Teraxion will come to market with a second 100 Gigabit coherent receiver design that is a third of the size of the OIF's form factor, measuring 23mmx18mm (0.32x the area of the OIF specification). The compact coherent receivers for 40 and 100Gbps will be available in sample form in the first quarter of 2013.
Teraxion's OIF-specification 100 Gig coherent receiver (left) for test purposes and its compact coherent receiver product. Source: Teraxion
"We match the OIF's performance with this design but there are also other key requirements from customers that are not necessarily in the OIF specification," says Guy.
The compact 100Gbps design is of interest to optical module and system vendors but there is no one view in terms of requirements or the desired line-side form-factor that follows the 5x7-inch MSA. Indeed there are some that are interested in developing a 100 Gigabit CFP module for metro applications, says Guy.
Roadmap
Teraxion's roadmap includes further integration of the coherent receiver's design. "We are using hybrid integration but eventually we will look at having the photo-detectors integrated within the material,” says Guy.
The small size of the coherent design means there is scope for additional functionality to be included. Teraxion says that customers are interested in integrating variable optical attenuators (VOAs). The local oscillator is another optical function that can be integrated within the coherent receiver.
In 2005 Teraxion acquired Dicos Technologies, a narrow line-width laser specialist. Teraxion's tunable narrow line-width laser product - a few kiloHertz wide - is available in the lab. "The purpose of this product is not to be deployed on the line card - right now," says Guy. "We believe this type of performance will be required for next-generation 100 Gig, 400 Gig, 1 Terabit coherent communication systems where you will need a very 'clean' local oscillator."
Teraxion is also working on developing a silicon-photonics-based modulator. The company has been exploring integrating Bragg gratings within silicon waveguides for which it has applied for patents. This is several years out, says Guy, but has the potential to enable high-speed modulators suited for short-reach datacom applications.