ROADMs: core role, modest return for component players
Next-generation reconfigurable optical add/ drop multiplexers (ROADMs) will perform an important role in simplifying network operation but optical component vendors making the core component - the wavelength-selective switch (WSS) - on which such ROADMs will be based should expect a limited return for their efforts.
"[Component suppliers] are going to be under extreme constraints on pricing and cost"
Sterling Perrin, Heavy Reading
That is one finding from an upcoming report by market research firm, Heavy Reading, entitled: "The Next-Gen ROADM Opportunity: Forecast & Analysis".
"We do see a growth opportunity [for optical component vendors]," says Sterling Perrin, senior analyst and author of the report. “But in terms of massive pools of money becoming available, it's not going to happen; it is a modest growth in spend that will go to next-generation ROADMs."
That is because operators’ capex spending on optical will grow only in single digits annually while system vendors that supply the next-generation ROADMs will compete fiercely, including using discounting, to win this business. "All of this comes crashing down on the component suppliers, such that they are going to be under extreme constraints on pricing and cost," says Perrin. The report will quantify the market opportunity but Heavy Reading will not discuss numbers until the report is published.
Next-generation ROADMs incorporate such features as colourless (wavelength-independence on an input port), directionless (wavelength routing to any port), contentionless (more than one same-wavelength light path accommodated at a port) and flexible spectrum (variable channel width for signal rates above 100 Gigabit-per-second (Gbps)).
Networks using such ROADMs promise to reduce service providers' operational costs. And coupled with the wide deployment of coherent optical transmission technology, next-generation ROADMs are set to finally deliver agile optical networks.
Other of the report’s findings include the fact that operators have been deploying colourless and directionless ROADMs since 2010, even though implementing such features using current 1x9 WSSs are cumbersome and expensive. However, operators wanting these features in their networks have built such systems with existing components. "Probably about 10% of the market was using colourless and directionless functions in 2010," says Perrin.
Service providers are requiring ROADMs to support flexible spectrum even though networks will likely adopt light paths faster than 100Gbps (400Gbps and beyond) in several years' time.
The need to implement a flexible spectrum scheme will force optical component vendors with microelectromechanical system (MEMS) technology to adopt liquid crystal technology – and liquid-crystal-on-silicon (LCoS) in particular - for their WSSs (see Comments). "MEMS WSS technology is great for all the stuff we do today - colourless, directionless and contentionless - but when you move to flexible spectrum it is not capable of doing that function," says Perrin. "The technology they (vendors with MEMS technology) have set their sights on - and which there is pretty much agreement as the right technology for flexible spectrum - is the liquid crystal on silicon." A shift from MEMS to LCoS for next-generation ROADM technology is thus to be expected, he says.
Perrin also highlights how coherent detection technology, now being installed for 100 Gbps optical transmission, can also implement a colourless ROADM by making use of the tunable nature of the coherent receiver. "It knocks out a bunch of WSSs added to the add/ drop," says Perrin. "It is giving a colourless function for free, which is a huge advantage."
Perrin views next-gen ROADMs as a money-saving exercise for the operators, not a money-making one. "This is hitting on the capex as well as the opex piece which is absolutely critical," he says. "You see the charts of the hockey stick of bandwidth growth and flat venue growth; that is what ROADMS hit at."
The Heavy Reading report will be published later this month.
Further reading:
ECOC 2011: Products and market trends
There were several noteworthy announcements at the European Conference on Optical Communications (ECOC) held in Geneva in September. Gazettabyte spoke to Finisar, Oclaro and Opnext about their ECOC announcements and the associated market trends.
100 Gig module
Opnext announced the first 100 Gigabit-per-second (Gbps) transponder at ECOC, a much anticipated industry development.
"Quite a few system vendors .... are looking at 'make-versus-buy' for the next-generation [of 100 Gig]."
Ross Saunders, Opnext
The OTM-100 is a dual-polarisation, quadrature phase-shift keying (DP-QPSK) coherent design that fits into a 5x7-inch module and meets the Optical Internetworking Forum's (OIF) multi-source agreement (MSA). The module's coherent receiver uses a digital signal processor (DSP) developed by NTT Electronics.
"At the moment we are going through the bring-up in the lab," says Ross Saunders, general manager, next-gen transport for Opnext Subsystems.
According to Opnext, system vendors that have their own 100Gbps coherent designs are also interested in the 100Gbps module.
"There are a few developing in-house [100Gbps designs] that are not interested in going for the module solution," says Saunders. "But there is another camp - quite a few system vendors - who have their first-generation solution that are looking at 'make-versus-buy' for the next-generation."
System vendors' first-generation 100Gbps designs use hard-decision forward error correction (FEC). But customers want a 100Gbps design with a reach that gets close to matching that of 10Gbps, 40Gbps DPSK and 40Gbps coherent designs, says Opnext.
"There is demand to go to the next-generation with its higher overhead and soft-decision FEC," says Saunders. "That [soft-decision FEC] buys another 2-3dB of performance so you don't need as many regeneration stages." Translated into distances, the reach using soft-decision FEC is 1500-1600km rather than 800-900km, says Saunders.
Opnext expects to deliver samples to lead customers before the year end.
Meanwhile, Oclaro is also developing a 100Gbps coherent module. "It is on track and we expect to ship in early 2012," says Per Hansen, vice president of product marketing, optical networks solutions at Oclaro.
100 Gig receiver
Oclaro announced an integrated 100Gbps coherent receiver at ECOC.
The company claims the device takes less than half the board area as defined by the OIF. "Board space is at a premium on line cards," says Robert Blum, director of product marketing for Oclaro's photonic components. "If you can increase functionality, that translates to lower cost."
100 Gig indium phosphide integrated receiver Source: OclaroThe device has two inputs and four outputs. The inputs are the received 100Gbps optical signal and the local oscillator and the outputs are from the four balanced detectors.
"The entire 90-degree hybrid mixing and the photo detection are all done in an indium phosphide single chip," says Blum.
40 Gig modules
Oclaro also announced it is shipping in volume its 40Gbps coherent transponder.
"There is a lot of interest from equipment vendors and service providers to use coherent in their networks," says Hansen "Coherent has advantages in the way it can overcome impairments."
Hansen says coherent will be used in the majority of new network deployments in future: "If you are deploying a network that is geared to 40Gbps and above, people will most likely deploy an all-coherent solution."
One reason why coherent is favoured is that the same technology can be scaled to 100Gbps, 400Gbps and even a Terabit.
Coherent technology, whose DSP is used for dispersion compensation, is also suited for mesh networks where switching wavelengths occurs. The coherent technology can compensate when it encounters new dispersion conditions following the switching.
In contrast 40Gbps direct-detection modules interest vendors for use in existing networks alongside 2.5Gbps and 10Gbps wavelengths, says Oclaro.
For networks geared to 40Gbps and above, people will most likely deploy an all-coherent solution
Per Hansen, Oclaro
"They can have very high power which can make it difficult for a new [high-speed] channel to live next to them but direct-detection modules are robust for those types of applications," says Hansen. "Where you will see people upgrading their existing networks, they will use DPSK or DQPSK transponders."
But Oclaro says that the split is not that clear-cut: 40Gbps coherent for new builds and direct-detection schemes when used alongside existing 10Gbps wavelengths. "There is a lot of variability in both of these approaches such that you can tailor them to different applications," says Hansen. "In the end, what it will come down to is what the customer is happy with and the price points, more than fundamental technology capabilities."
40G client-side interfaces
Finisar demonstrated at ECOC a serial 40Gbps CFP module that meets the 2km 40GBASE-FR standard.
"This will be the first 40 Gig serial module that is in a pluggable form factor," says Rafik Ward, vice president of marketing at Finisar. Indeed Finisar's CFP is a tri-rate design that also supports the ITU-T OC-768 SONET/SDH very short reach (VSR) and OTU3 standards.
The FR interface is the IEEE's 40 Gigabit Ethernet equivalent of the existing OC-768 VSR interface. The original 300pin VSR interface has a 16-channel electrical interface, each operating at 2.5Gbps, while the CFP module uses 10Gbps electrical channels.
IP routers can now be connected to DWDM platforms using the pluggable module, says Finisar. The pluggable will also enable system vendors to design denser line cards with two or even four CFP interfaces, as well as the option of changing the CFP to support other standards as required.
The tri-rate FR pluggable module's power consumption will be below 8W, says Finisar, which is shipping samples to customers.
Meanwhile, Opnext has announced it is sampling its 40GBASE-LR4, the 10km 40 Gigabit Ethernet interface, in a QSFP module. "It will be readily available by the end of the year," says Jon Anderson, director of technology programme at Opnext.
"The 40GBASE-LR4 [QSFP] will be readily available by the end of the year"
Jon Anderson, Opnext
Tunable laser XFP
Opnext and Oclaro have both announced 10Gbps tunable XFPs at ECOC. Having two new suppliers of tunable XFPs joining JDS Uniphase will increase market competition and reduce the price of the tunable pluggable.
"It really is a replacement for 300-pin transponders," says Blum. "You can now migrate 10Gbps links to a pluggable form factor."
Oclaro's tunable XFP is released for production. Opnext says its tunable XFP will be in volume production by early 2012.
ROADMs get 1x20 WSS
Finisar announced a 1x20 high-port count wavelength selective switch (WSS). The WSS supports a flexible spectrum grid that allows the channel width to be varied in increments of 12.5GHz, enabling future line rates above 100Gbps to be supported.
"This [1x20 WSS] has the possibility to enable some pretty interesting applications for next generation - colourless, directionless, contentionless networks," says Ward.
"This [40GBASE-FR] will be the first 40 Gig serial module that is in a pluggable form factor"
Rafik Ward, Finisar.
One common application of the 1x20 WSS is implementing a multi-degree node. The degree refers to the number of points that node branches out to in a mesh network, says Finisar. "The fundamental question is how many ports do you have in that node?" explains Ward.
For example, an 8-degree node communicates with eight other points in the mesh. With a 1x20 WSS, the architecture uses eight of the 20 as express ports - those 8 ports interfacing with other WSSs in the node - while the remaining 12 ports on that 1x20 WSS are used as add and drop ports.
"The advantage of a 1x20 WSS in this case is enabling a large number of express ports and a large number of add ports," says Ward.
A second application is for colourless or tunable multiplexing.
"One of the problems today enabling colourless ROADM operation is that typically the muxes and demuxes used are AWGs," says Ward. Having a tunable laser is all well and good but it becomes hardwired to a specific port because of the arrayed waveguide grating (AWG). "That specific port is configured for that particular wavelength," he says.
To make an 80-channel colourless design, that does not require manual intervention, four 1x20 WSSs are placed side-by-side with a 1x4 WSS connecting the four. This is a more elegant and compact than using existing 1x9 WSSs, which requires more than twice as many WSS units.
Pump lasers
Oclaro announced two 980nm pump laser products that enable more compact, lower-power amplifier designs.
"Board space is at a premium on line cards"
Robert Blum, Oclaro
One is an uncooled 980nm 500mW pump laser and the second is two 600mW pump lasers in a single package. The dual-pump laser product halves the footprint and requires a single thermo-electric cooler only.
"The power consumption is significantly lower than what it would be for two discrete pump lasers," says Blum. "The 300mW uncooled pump laser doesn't go away but for dual-stage or mid-stage optical amplifiers instead of using multiple [300mW] lasers, you can use a single package," says Blum.
GPON-on a-stick
Finisar announced a 'GPON-on-a-stick' SFP module. The result of its acquisition of Broadway Networks in 2010, the SFP-based GPON optical network unit (ONU) enables an Ethernet switch to be connected to a PON. The product is aimed at enterprises as well as large residential premises. The GPON stick complements the company's existing EPON stick.
Further information:
ECOC 2011 Market focus presentations, click here
Rapid progress in optical transport seen at ECOC 2011, Ovum's Karen Liu, click here
Finisar and Capella enter 1×20 WSS market; signals shift, Ovum's Daryl Inniss, click here
Capella: Why the ROADM market is a good place to be
The reconfigurable optical add-drop multiplexer (ROADM) market has been the best performing segment of the optical networking market over the last year. According to Infonetics Research, ROADM-based wavelength division multiplexing (WDM) equipment grew 20% from Q2, 2010 to Q1, 2011 whereas the overall optical networking market grew 7%.
“It’s the Moore’s Law: Every two years we are doubling the capacity in terms of channel count and port count”
Larry Schwerin, Capella
The ROADM market has since slowed down but Larry Schwerin, CEO of wavelength-selective-switch (WSS) provider, Capella Intelligent Subsystems, says the market prospects for ROADMs remain solid.
Capella makes WSS products that steer and monitor light at network nodes, while the company’s core intellectual property is closed-loop control. Its WSS products are compact, athermal designs based on MEMS technology that switch and monitor light.
Schwerin compares Capella to a plumbing company: “We clean out pipes and those pipes happen to be fibre-optics ones.” The reason such pipes need ‘cleaning’ – to be made more efficient - is because of the content they carry. “It is bandwidth demand and the nature of the bandwidth which has changed dramatically, that is the fundamental driver here,” says Schwerin.
Increasingly the content is high-bandwidth video and streamed to end-user devices no longer confined to the home, while the video requested is increasingly user-specific. Such changes in the nature of content are affecting the operators’ distribution networks.
“Using Verizon as an example, they are now pushing 50 wavelengths per fibre in the metro,” says Schwerin. Such broad lanes of traffic arrive at network congestion points where certain fibre is partially used while other fibre is heavily used. “What they [operators] need is a vehicle that allows them to dynamically and remotely reassign those wavelengths on-the-fly,” says Schwerin. “That is what the ROADM does.”
Capella attributes strong ROADM sales to a maturing of the technology coupled with a price reduction. The technology also brings valuable flexibility at the optical layer. “It [ROADM] extends the life of the existing infrastructure, avoiding the need for capital to put new fibre in - which is the last thing the operators want to do,” says Schwerin.
$20M funding
Capella raised US $20M in April as part of its latest funding round. The funding is being used for capital expansion and R&D. “We are working on new engine technology, new patentable concepts,” says Schwerin. “We were at Verizon a few weeks ago doing a world-first demo which we will be putting out as a press release.” For now the company will say that the demonstration is research-oriented and will not be implemented within ROADM systems anytime soon.
“You have to be competitive in this market, that is the downfall of our sector. People getting 30 or 40% gross margins and calling that a win – that is not a win - that is why this sector is in trouble”
One investor in the latest funding round is SingTel Innov8, the investment arm of the operator SingTel. Schwerin says it has no specific venture with the operator but that SingTel will gain insight regarding switching technologies due to the investment. “We will sit down with them and talk about their plans for network evolution and what is technologically possible,” says Schwerin, who points out that many of the carriers have lost contact with technologies since they shed their own large, in-house R&D arms.
Cappella offers two 1x9 WSS products and by the end of this year will also offer a 1x20 product. “It’s the Moore’s Law: Every two years we are doubling the capacity in terms of channel count and port count,” says Schwerin.
“We have a reasonable share of design wins shipping in volume - we have thousands of switches deployed throughout the world,” says Schwerin. “We are not of the size of a JDSU or a Finisar but our objective within the next 18 months is to capture enough market share that you would see us as a main supplier of that ilk.”
The CEO stresses that Capella’s presence a decade after the optical boom ended proves it is offering distinctive products. “Our whole business model is about innovation and differentiation,” says Schwerin.
But as a start-up how can Capella compete with a JDSU or a Finisar? “I have these conversations with the carriers: if all they are doing is looking for second or third sourcing of commodity product parts then there is no room for a company like a Capella.”
The key is taking a dumb switch and turning it into a complete wavelength managed solution that can be easily added within the network.
Schwerin also stresses the importance of ROADM specsmanship: wider lightpath channel passbands, lower insertion loss, smaller size, lower power consumption and competitive pricing: “You have to be competitive in this market, that is the downfall of our sector,” says Schwerin. “People getting 30 or 40% gross margins and calling that a win – that is not a win - that is why this sector is in trouble.”
Advanced ROADM features
There has been much discussion in the last year regarding the four advanced attributes being added to ROADM designs: colourless, directionless, contentionless and gridless or CDCG for short.
Interviewing six system vendors late last year, while all claimed they could support CDCG features, views varied as to what would be needed and by when. Meanwhile all the system vendors were being cautious until it was clearer as to what operators needed.
Schwerin says that what the operators really want is a ‘touchless’ ROADM. Capella says its platform is capable of supporting each of the four attributes and that the company has plans for implementing each one. “Just because the carriers say they want it, that doesn’t mean that they are willing to pay for it,” says Schwerin. “And given the intense pricing pressure our system friends are in, they are rightly being cautious.”
Capella says that talking to the carriers doesn’t necessarily answer the issue since views vary as to what is needed. “The one [attribute] that seems clearest of all is colourless,” says Schwerin. And colourless is served using higher-port-count WSSs.
The directionless attribute is more a question of implementation and the good news is that it requires more WSSs, says Schwerin. Contentionless addresses the issue of wavelength blocking and is the most vague, a requirement that has even “faded away a bit”. As for gridless, that may be furthest out as it has ramifications in the network.
Schwerin says that Capella is seeing requests for reduced WSS switching times as well as wavelength tracking, tagging a wavelength whose signature can be identified optically and which is useful for network restoration and when wavelengths are passed between carriers’ networks.
Roadmap
In terms of product plans, Capella will launch a 1x20 WSS product later this year. The next logical step in the development of WSS technology is moving to a solid-state-based design.
“All of the the technologies out there today– liquid crystal, MEMS, liquid-crystal-on-silicon - are all free space [designs],” says Schwerin. “We have a solid-state engine in the middle [of our WSS] and we are down to five photonic-integrated-circuit components so the obvious next stage is silicon photonics.”
Does that mean a waveguide-based design? “Something of that form – it may not be a waveguide solution but something akin to that - but the idea is to get it down to a chip,” says Schwerin. “We are not pure silicon photonics but we are heading that way.”
Such a compact chip-based WSS design is probably five years out, concludes Schwerin.
Further information:
A Fujitsu ROADM discussion with Verizon and Capella – a Youtube 30-min video