Cyan's stackable optical rack for data centre interconnent
"The drivers for these [data centre] guys every day of the week is lowest cost-per-gigabit"
Joe Cumello
The amount of traffic moved between data centres can be huge. According to ACG Research, certain cloud-based applications shared between data centres can require between 40 to 500 terabits of capacity. This could be to link adjacent data centre buildings to appear as one large logical one, or connect data centres across a metro, 20 km to 200 km apart. For data centres separated across greater distances, traditional long-haul links are typically sufficient.
Cyan says it developed the N-series platform following conversations conducted with internet content providers over the last two years. "We realised that the white box movement would make its way into the data centre interconnect space," says Cumello.
White box servers and white box switches, manufactured by original design manufacturers (ODMs), are already being used in the data centre due to their lower cost. Cyan is using a similar approach for its N-Series, using commercial-off-the-shelf hardware and open software.
"The drivers for these [data centre] guys every day of the week is lowest cost-per-gigabit," says Cumello.
N-Series platform
Cyan's N-Series N11 is a 1-rack-unit (1RU) box that has a total capacity of 800 Gigabit-per-second (Gbps). The 1RU shelf comprises two units, each using two client-side 100Gbps QSFP28s and a line-side interface that supports 100 Gbps coherent transmission using PM-QPSK, or 200 Gbps coherent using PM-16QAM. The transmission capacity can be traded with reach: using 100 Gbps, optical transmission up to 2,000 km is possible, while capacity can be doubled using 200 Gbps lightpaths for links up to 600 km. Cyan is using Clariphy's CL20010 coherent transceiver/ framer chip. Stacking 42 of the 1RUs within a chassis results in an overall capacity - client side and line side - of 33.6 terabit.
There is a whole ecosystem of companies competing to drive better capacity and scale
The N-Series N11 uses a custom line-side design but Cyan says that by adopting commercial-off-the-shelf design, it will benefit from the pluggable line-side optical module roadmap. The roadmap includes 200 Gbps and 400 Gbps coherent MSA modules, pluggable CFP2 and CFP4 analogue coherent optics, and the CFP2 digital coherent optics that also integrates the DSP-ASIC.
"There is a whole ecosystem of companies competing to drive better capacity and scale," says Cumello. "By using commercial-off-the-shelf technology, we are going to get to better scale, better density, better energy efficiency and better capacity."
To support these various options, Cyan has designed the chassis to support 1RU shelves with several front plate options including a single full-width unit, two half-width ones as used for the N11, or four quarter-width units.
Open software
For software, the N-series platform uses a Linux networking operating system. Using Linux enables third-party applications to run on the N-series, and enables IT staff to use open source tools they already know. "The data centre guys use Linux and know how to run servers and switches so we have provided that kind of software through Cyan's Linux," says Cumello. Cyan has also developed its own networking applications for configuration management, protocol handling and statistics management that run on the Linux operating system.
The open software architecture of the N-Series. Also shown are the two units that make up a rack. Source: Cyan.
"We have essentially disaggregated the software from the hardware," says Cumello. Should a data centre operator chooses a future, cheaper white box interconnect product, he says, Cyan's applications and Linux networking operating system will still run on that platform.
The N-series will be available for customer trials in the second quarter and will be available commercially from the third quarter of 2015.
Infinera targets the metro cloud
Infinera has styled its latest Cloud Xpress product used to connect data centres as a stackable platform, similar to how servers and storage systems are built. The development is another example of how the rise of the data centre is influencing telecoms.
"There is a drive in the industry that is coming from the data centre world that is starting to slam into the telecom world," says Stuart Elby, Infinera's senior vice president of cloud network strategy and technology.
Cloud Xpress is designed to link data centres up to 200km apart, a market Infinera coins the metro cloud. The two-rack-unit-high (2RU) stackable box features Infinera's 500 Gigabit photonic integrated circuit (PIC) for line side transmission and a total of 500 Gigabit of client side links made up of 10, 40 or 100 Gigabit interfaces. Typically, up to 16 units will be stacked in a rack, providing 8 Terabits of transmission capacity over a fibre.
Cloud Xpress has also been designed with the data centre's stringent power and space requirements in mind. The resulting platform has significantly improved power consumption and density metrics compared to traditional metro networking platforms, claims Infinera.
Metro split
Elby describes how the metro network is evolving into two distinct markets: metro aggregation and metro cloud. Metro aggregation, as the name implies, combines lower speed multi-service traffic from consumers' broadband links and from enterprises into a hub where it is switched onto a network backbone. Metro cloud, in contrast, concerns date centre interconnect: point-to-point links that, for the larger data centres, can total several terabits of capacity.
Cloud Xpress is Infinera's first metro platform that uses its PIC. "We have plans to offer it all the way out to ultra long haul," says Elby. "There are some data centres that need to get tied between continents."
Cloud Xpress is being aimed at several classes of customer: internet content providers companies (or webcos), entreprises, cloud operators and traditional service providers. The primary end users are webcos and enterprises, which is why the platform is designed as a rack-and-stack. "These are not networking companies, they are data centre ones; they think of equipment in the context of the data centre," says Elby.
But Infinera expects telcos will also adopt Cloud Xpress. They need to connect their data centres and link data centres to points-of-presence, especially when increasing amounts of traffic from end users now goes to the cloud. Equally, a business customer may link to a cloud service provider through a colocation point, operated by companies such as Equinix, Rackspace and Verizon Terremark.
"There will be a bleed-over of the use of this product into all these metro segments," says Elby. "But the design point [of Cloud Xpress] was for those that operate data centres more than those that are network providers."
Google has shared that a single internet search query travels on average 2,400km before being resolved, while Facebook has revealed that a single http request generates some 930 server-to-server interactions.
The Magnification Effect
Webcos' services generate significantly more internal traffic than the triggering event, what Elby calls the magnification effect.
Google has shared that a single internet search query travels on average 2,400km before being resolved, while Facebook has revealed that a single http request generates some 930 server-to-server interactions. These servers may be in one data centre or spread across centres.
"It is no longer one byte in, one byte out," says Elby. "The amount of traffic generated inside the network, between data centres, is much greater than the flow of traffic into or out of the data centre." This magnification effect is what is driving the significant bandwidth demand between data centres. "When we talk to the internet content providers, they talk about terabits," says Elby.
Cloud Xpress
Cloud Xpress is already being evaluated by customers and will be generally available from December.
The stackable platform will have three client-side faceplate options: 10 Gig, 40 Gig and 100 Gig. The 10 Gig SFP+ faceplate is the sweet spot, says Elby, and there is also a 40 Gig one, while the 100 Gig is in development. "In the data centre world, we are hearing that they [webcos] are much more interested in the QSFP28 [optical module]."
Infinera says that the Ethernet client signals connect to a simple mapping function IC before being placed onto 100 Gig tributaries. Elby says that Infinera has minimised the latency through the box, to achieve 4.4 microseconds. This is an important requirement for certain data centre operators.
The 500 Gig PIC supports Infinera's 'instant bandwidth' feature. Here, all the 500 Gig super-channel capacity is lit but a user can add 100 Gig increments as required. This avoids having to turn up wavelengths and simplifies adding more capacity when needed.
The Cloud Xpress rack can accommodate 21 stackable units but Elby says 16 will be used typically. On the line side, the 500 Gigabit super-channels are passively multiplexed onto a fibre to achieve 8 Terabits. The platform density of 500 Gig per rack unit (500 Gig client and 500 Gig line side per 2RU box), exceeds any competitor's metro platform, says Elby, saving important space in the data centre.
The worse-case power consumption is 130W-per-100 Gig, an improvement on the power consumption performance of competitors' platforms. This is despite the fact that coherent detection is always used, even for links as short as between a data centre's buildings. "We have different flavours of the optical engine for different reaches," says Elby. "It [coherent] is just used because it is there."
The reduced power consumption of Cloud Xpress is achieved partly because of Infinera's integrated PIC, and by scrapping Optical Transport Network (OTN) framing and switching which is not required. "There are no extra bells and whistles for things that aren't needed for point-to-point applications," says Elby. The stackable nature of the design, adding units as needed, also helps.
The Cloud Xpress rack can be controlled using either Infinera's management system or software-defined networking (SDN) application programming interfaces (APIs). "It supports the sort of interfaces the SDN community wants: Web 2.0 interfaces, not traditional telco ones."
Infinera is also developing a metro aggregation platform that will support multi-service interfaces and aggregate flows to the hub, a market that it expects to ramp from 2016.
Ranovus readies its interfaces for deployment
- Products will be deployed in the first half of 2015
- Ranovus has raised US $24 million in a second funding round
- The start-up is a co-founder of the OpenOptics MSA; Oracle is now also an MSA member.
Ranovus says its interconnect products will be deployed in the first half of 2015. The start-up, which is developing WDM-based interfaces for use in and between data centres, has raised US $24 million in a second stage funding round. The company first raised $11 million in September 2013.
Saeid Aramideh"There is a lot of excitement around technologies being developed for the data centre," says Saeid Aramideh, a Ranovus co-founder and chief marketing and sales officer. He highlights such technologies as switch ICs, software-defined networking (SDN), and components that deliver cost savings and power-consumption reductions. "Definitely, there is a lot of money available if you have the right team and value proposition," says Aramideh. "Not just in Silicon Valley is there interest, but in Canada and the EU."
The optical start-up's core technology is a quantum dot multi-wavelength laser which it is combining with silicon photonics and electronics to create WDM-based optical engines. With the laser, a single gain block provides several channels while Ranovus is using a ring resonator implemented in silicon photonics for modulation. The company is also designing the electronics that accompanies the optics.
Aramideh says the use of silicon photonics is a key part of the design. "How do you enable cost-effective WDM?" he says."It is not possible without silicon photonics." The right cost points for key components such as the modulator can be achieved using the technology. "It would be ten times the cost if you didn't do it with silicon photonics," he says.
The firm has been working with several large internet content providers to turn its core technology into products. "We have partnered with leading data centre operators to make sure we develop the right products for what these folks are looking for," says Aramideh.
In the last year, the start-up has been developing variants of its laser technology - in terms of line width and output power - for the products it is planning. "A lot goes into getting a laser qualified," says Aramideh. The company has also opened a site in Nuremberg alongside its headquarters in Ottawa and its Silicon Valley office. The latest capital will be used to ready the company's technology for manufacturing and recruit more R&D staff, particularly at its Nuremberg site.
Ranovus is a founding member, along with Mellanox, of the 100 Gigabit OpenOptics multi-source agreement. Oracle, Vertilas and Ghiasi Quantum have since joined the MSA. The 4x25 Gig OpenOptics MSA has a reach of 2km-plus and will be implemented using a QSFP28 optical module. OpenOptics differs from the other mid-reach interfaces - the CWDM4, PSM4 and the CLR4 - in that it uses lasers at 1550nm and is dense wavelength-division multiplexed (DWDM) based.
It is never good that an industry is fragmented
That there are as many as four competing mid-reach optical module developments, is that not a concern? "It is never good that an industry is fragmented," says Aramideh. He also dismisses a concern that the other MSAs have established large optical module manufacturers as members whereas OpenOptics does not.
"We ran a module company [in the past - CoreOptics]; we have delivered module solutions to various OEMs that are running is some of the largest networks deployed today," says Aramideh. "Mellanox [the other MSA co-founder] is also a very capable solution provider."
Ranovus plans to use contract manufacturers in Asia Pacific to make its products, the same contract manufacturers the leading optical module makers use.
Table 1: The OpenOptics MSA
End markets
"I don't think as a business, anyone can ignore the big players upgrading data centres," says Aramideh. "The likes of Google, Facebook, Amazon, Apple and others that are switching from a three-tier architecture to a leaf and spine need longer-reach connectivity and much higher capacity." The capacity requirements are much beyond 10 Gig and 40 Gig, and even 100 Gig, he says.
Ranovus segments the adopters of interconnect into two: the mass market and the technology adopters. "Mass adoption today is all MSA-based," says Aramideh. "The -LR4 and -SR10, and the same thing is happening at 100 Gig with the QSFP28." The challenge for the optical module companies is who has the lowest cost.
Then there are the industry leaders such as the large internet content providers that want innovative products that address their needs now. "They are less concerned about multi-source standard-based solutions if you can show them you can deliver a product they need at the right cost," says Aramideh.
Ranovus will offer an optical engine as well as the QSFP28 optical module. "The notion of the integration of an optical engine with switch ICs and other piece parts in the data centre are more of an urgent need," he says.
Using WDM technology, the company has a scalable roadmap that includes 8x25 Gig and 16x25 Gig (400 Gig) designs. Also, by adding higher-order modulation, the technology will scale to 1.6 Terabit (16x100 Gig), says Aramideh.
I don't see a roadmap for coherent to become cost-effective to address the smaller distances
Ranovus is also working on interfaces to link data centres.
"These are distances much shorter than metro/ regional networks," says Aramideh, with the bulk of the requirements being for links of 15 to 40km. For such relatively short distances, coherent detection technology has a high-power consumption and is expensive. "I don't see a roadmap for coherent to become cost-effective to address the smaller distances," says Aramideh.
Instead, the company believes that a direct-detection interconnect that supports 15 to 40km and which has a spectral efficiency that can scale to 9.6 Terabit is the right way to go. If that can be achieved, then switching from coherent to direct detection becomes a no-brainer, he says. "For inter-data-centres, we are really offering an alternative to coherent."
The start-up says its technology will be in product deployment with lead customers in the first half of 2015.
ECOC 2014: Industry reflections on the show
Gazettabyte asked several attendees at the recent ECOC show, held in Cannes, to comment on key developments and trends they noted, as well as the issues they will track in the coming year.
Daryl Inniss, practice leader, components at market research firm, Ovum
It took a while to unwrap what happened at ECOC 2014. There was no one defining event or moment that was the highlight of the conference.
The location was certainly beautiful and the weather lovely. Yet I felt the participants were engaged with critical technical and business issues, given how competitive the market has become.
Kaiam’s raising US $35 million, Ranovus raising $24 million, InnoLight Technology raising $38 million and being funded by Google Capital, and JDSU and Emcore each splitting into two companies, all are examples of the shifting industry structure.
On the technology and product development front, advances in 100 Gig metro coherent solutions were reported although products are coming to market later than first estimated. The client-side 100 Gig is transitioning to CFP2. Datacom participants agree that QSFP28 is the module but what goes inside will include both parallel single mode solutions and wavelength multiplexed ones.
Finisar’s 50 Gig transmission demonstration that used silicon photonics as the material choice surprised the market. Compared to last year, there were few multi-mode announcements. ECOC 2014 had little excitement and no one defining show event but there were many announcements showing the market’s direction.
There is one observation from the show, which while not particularly exciting or sexy, is important, and it seems to have gone unnoticed in my opinion. Source Photonics demonstrated the 100GBASE-LR4, the 10km 100 Gigabit Ethernet standard, in the QSFP28 form factor. This is not new as Source Photonics also demonstrated this module at OFC. What’s interesting is that no one else has duplicated this result.
There will be demand for a denser -LR4 solution that’s backward compatible with the CFP, CFP2, and CFP4 form factors. It is unlikely that the PSM4, CWDM4, or CLR4 will go 10km and they are not optically compatible with the -LR4. The market is on track to use the QSFP28 for all 100 Gig distances so it needs the supporting optics. The Source Photonics demonstration shows a path for 10km. We expect to see other solutions for longer distances over time.
One surprise at the show was Finisar's and STMicroelectronics's demonstration of 50 Gig non-return-to-zero transmission over 2.2km on standard single mode fiber. The transceiver was in the CFP4 form factor and uses heterogeneous silicon technologies inside. The results were presented in a post-deadline paper (PD.2.4). The work is exciting because it demonstrates a directly modulated laser operating above 28 Gig, the current state-of-the-art.
The use of silicon photonics is surprising because Finisar has been forced to defend its legacy technology against the threat of transceivers based on silicon photonics. These results point to one path forward for next-generation 100 Gig and 400 Gig solutions.
In the coming year, I’m looking for the dominant metro 100G solution to emerge. When will the CFP2 analogue coherent optical module become generally available? Multiple suppliers with this module will help unleash the 100 Gig line-side transmission market, drive revenue growth and the development for the next-generation solution.
Slow product development gives competing approaches like the digital CFP a chance to become the dominant solution. At present, there is one digital CFP vendor with a generally available product, Acacia Communications, with a second, Fujitsu Optical Components, having announced general availability in the first half of 2015.
Neal Neslusan, vice president of sales and marketing at fabless chip company, MultiPhy.
It was impressive to see Oclaro's analogue CFP2 for coherent applications on the show floor, albeit only in loopback mode. Equally impressive was seeing ClariPhy's DSP on the evaluation board behind the CFP2.
I saw a few of the motherboard-based optics solutions at the show. They looked very interesting and in questioning various folks in the business I learned that for certain data centre applications these optics are considered acceptable. Indeed, they represent an ability to extract much higher bandwidth from a given motherboard as compared to edge-of-the-board based optics, but they are not pluggable.
Traditionally, pluggable optics has been the mainstay of the datacom and enterprise segments and these motherboard-based optics have been relegated to supercomputing. This is just another example, in my opinion, of how the data centre market is becoming distinct from the datacom market.
Where there any surprises at the show? I was surprised and alarmed at the cost of the Martini drinks at the hotel across the street from the show, and they weren't even that good!
Regarding developments in the coming year, the 8x50 Gig versus 4x100 Gig fight in the IEEE is clearly a struggle I will follow. I think it will have a great impact on product development in our industry. If 8x50 Gig wins, it may be one of the few times in the history of our industry that a less advanced solution is chosen over a more advanced and future-proofed one.
The physical size of the next-generation Terabit Ethernet switch chips will have a much larger impact on the optics they connect to in the coming years, compared to the past. This work combined with the motherboard-based optics may create a significant change in the solutions brought to bear for high-performance communications.
John Lively, principal analyst at market research firm, LightCounting.
There were several developments that I noted at the show. ECOC helped cement the view that 100 Gig coherent is mainstream for metro networks. Also more and more system vendors are incorporating Raman/ remote optically pumped amplifier (ROPA) into their toolkit. ROPA is a Raman-based amplifier where the pump is located at one end of the link, not in some intermediate node. Another trend evident at ECOC is how the network boundary between terrestrial and submarine is blurring.
As for developments to watch, I intend to follow mobile fronthaul/ backhaul, higher speed transceiver developments, of course, and how the mega-data-centre operators are disrupting networks, equipment, and components.
For the ECOC reflections, final part, click here
OFC 2014 product round-up - Final part
The industry is moving at a clip to fill the void in 100 Gig IEEE standards for 100m to 2km links. Until now, the IEEE 10km 100GBASE-LR4 and the 10x10 MSA have been the interfaces used to address such spans.
But responding to data centre operators, optical players are busy developing less costly, mid-reach MSAs, as was evident at the OFC exhibition and conference, held in San Francisco in March.
Meanwhile, existing IEEE 100 Gigabit standards are skipping to the most compact CFP4 and QSFP28 form factors. The -LR4 standard was first announced in a CFP in 2010, and moved to the CFP2, half the size of the CFP, in 2013. Now, several companies have detailed CFP4 -LR4 products, while Source Photonics has gone one better, announcing the standard in a QSFP28.
The CFP4 is half the size of the CFP2, while the QSFP28 is marginally smaller than the CFP4 but has a lower power consumption: 3.5W compared to the CFP4's 6W.
Timeline of some pluggable announcements at recent OFCs. Source: Gazettabyte
The mid-reach landscape
Several interfaces for mid-reach interconnect were detailed at OFC. And since the show, two MSAs have been detailed: the CWDM4 and the CLR4 Alliance.
At OFC, the OpenOptics MSA backed by Mellanox Technologies and Ranovus, was announced. Skorpios Technologies demoed its CLR4 module that has since become the CLR4 Alliance. And vendors discussed the Parallel Single Mode (PSM4) initiative that was first detailed in January.
Switch vendor Mellanox Technologies and module start-up Ranovus announced the OpenOptics MSA at OFC. The QSFP-based MSA uses a single-mode fibre and WDM transmission around 1550nm to address data centre links up to 2km.
Saeid Aramideh of Ranovus says that the MSA using its laser and silicon photonics technologies will deliver significant cost, power and size advantages {add link}. "But the 1550nm WDM connection is open to any technology," says Aramideh, chief marketing and sales officer at Ranovus. "It does not have to be silicon photonics."
The first MSA product, a 100 Gig QSFP28, uses 4x25 Gig channels. "The channel spacing for the MSA is flexible to be 50GHz or more," says Aramideh. The MSA is scalable to 400 Gig and greater rates. The 100 Gig QSFP28 technology is several months away from sampling.
Skorpios Technologies demonstrated its QSFP28-CLR4 transceiver although the details of the MSA have yet to be detailed. Skorpios is a silicon photonics player and uses heterogenous integration where the lasers, modulators, detectors and optical multiplexer and de-multiplexer are monolithically integrated on one chip.
The PSM4 MSA is another initiative designed to tackle the gap between IEEE short and long reach standards. Backed by players such as Avago Technologies, Brocade, JDSU, Luxtera, Oclaro, and Panduit, the 100 Gig standard is defined to operate in the 1295-1325nm spectral window and will have a reach of at least 500m.
ColorChip demonstrated a 100 Gig (4x25 Gig) QSFP28 with a 2km reach at the show. The design uses uncooled directly modulated lasers to achieve the 3.5W power consumption. Since the show Colorchip is one of the member companies backing the CLR4 Alliance and the demoed QSFP matches the first details of the new MSA's spec.
100GBASE-LR4 moves to CFP4 and QSFP28
The IEEE 100GBASE-LR4 standard is transitioning to the smallest modules. At OFC, vendors detailed the first CFP4s while Source Photonics announced the -LR4 in a QSFP28.
Source Photonics says its transceiver consumes 3.5W. The QSFP28 form factor achieves up to a fourfold increase in face plate density compared to the CFP2: up to 48 modules compared to a dozen CFP2 modules, says the company, which expects first QSFP28 -LR4 samples in mid-2014.
Meanwhile, Avago Technologies, Finisar, Fujitsu Optical Components and JDSU all detailed their first CFP4 -LR4 modules.
JDSU says that when it developed the optics for its CFP2 -LR4, it was already eyeing the transition to the CFP4 and QSFP28 form factors. To achieve the -LR4 spec in the 6W CFP4, a key focus are the clock data recover (CDR), driver and trans-impedance amplifier chips. "A decent amount of the power consumption is wrapped up in the ICs that do the CDR and a variety of the digital functions behind the photonics," says Brandon Collings, JDSU's CTO for communications and commercial optical products. JDSU expects general availability of its CFP4 -LR4 later this year.
Finisar's -LR4 is its second CFP4 product; at ECOC 2013 it showcased a 100m, 100GBASE-SR4 CFP4. Finisar says its -LR4 uses distributed feedback (DFB) lasers and consumes 4.5W, well within the CFP4's 6W power profile. At OFC, the CFP4 was demonstrated working with CFP2 and CFP -LR4 modules. Finisar's CFP4 will sample later this year.
Avago announced availability of its -LR4 transmit optical subassembly (TOSA) and receive optical subassembly (ROSA) products for the CFP4, along with its CFP4 module which it says will be available next year. Fujitsu Optical Components also used OFC to demo its CFP4 -LR4.
40km Extended Reach Lite
Oclaro and Finisar detailed a tweak to the 100 Gig Extended Reach standard: the 40km, 100GBASE-ER4.
The IEEE standard uses a power-hungry semiconductor optical amplifier (SOA) prior to the PIN photodetector to achieve 40km. The module vendors have proposed replacing the SOA and PIN with an avalanche photo diode (APD) and external forward error correction to reduce the power consumption while maintaining the optical link budget. The changed spec is dubbed 100GBASE-ER4 Lite.
"Trying to achieve the power envelopes required for the CFP4 and QSFP28 using SOAs is going to be too hard," says Kevin Granucci, vice president of strategy and marketing at Oclaro.
Oclaro demonstrated a ER4-Lite in a CFP2. The module supports 100 Gigabit Ethernet and the Optical Transport Network (OTN) OTU-4 rates, and consumes less than 9W. "We are using the CFP2 as the first proof-of-concept," says Granucci. "For the 6W CFP4 and the 3.5W QSFP28, we think this is the only solution available."
At OFC Finisar demonstrated the link's feasibility, which it refers to as ER4f, using four 28 Gig lasers and four 28 Gig APDs.
Oclaro says it is seeing customer interest in the ER4 Lite, and points out that there are many 10 Gig 40km links deployed, especially in China. "The ER4 Lite will provide an update path to 100 Gig," says Granucci.
VCSELs: serial 40 Gig and the 400 Gig CDFP
Finisar showcased a VCSEL operating at 40 Gig at OFC. State-of-the-art VCSEL interfaces run up to 28 Gig. Finisar's VCSEL demonstration was to show the commercial viability of higher-speed VCSELs for single channel or parallel-array applications. "We believe that VCSELs have not run out of steam," says Rafik Ward, vice president of marketing at Finisar. The 40 Gig VCSEL demonstration used non-return-to-zero (NRZ) signalling, "no higher-order modulation is being used", says Ward.
IBM T.J.Watson Research Center has published an IEEE paper with Finisar involving a 56Gbps optical link based on an 850nm VCSEL.
Finisar also demonstrated an CDFP-based active optical cable. The CDFP is a 400 Gig MSA that uses 16 x 25 Gig VCSEL channels in each direction. Such an interface will address routing, high-performance computing and proprietary interface requirements, says Finisar. The demonstration showcased the technology; Finisar has yet to announce interface products or reaches.
Short reach 100G and 4x16 Gig Fibre QSFPs
Avago Technologies announced a 100GBASE-SR4 implemented using the QSFP28. Avago's I Hsing Tan, segment marketing manager for Ethernet and storage optical transceivers, says there has been a significant ramp in data centre demand for the 40GBASE-SR4 QSFP+ in the last year. "Moving to the next generation, the data centre operator would like to keep the same [switch] density as the QSFP+, and the QSFP28 MSA offers the same form factor," he says.
The QSFP28 differs from the QSFP+ is that its electrical connector is upgraded to handle 28 Gigabit-per-lane data rates. Avago says the -SR4 module will be generally available next year.
Avago also announced a 4x16 Gigabit Fibre Channel QSFP+ transceiver. The industry is transitioning from 8 to 16 Gig Fibre Channel, says Avago, and this will be followed by 32 Gig serial and 4x32 Gig Fibre Channel modules.
The company has announced a 4x16 Gig QSFP+ to continue the increase in platform channel density while the industry transitions from 16 to 32 Gig Fibre Channel. "This solution is going to provide the switch vendor a 3x increase in density at half the power dissipation per channel for 16 Gig Fibre Channel, before the 32 bit Fibre Channel come to maturity in three to five years," says Tan.
Avago has just announced that it has shipped over half a million QSFP+ modules.
Optical engines
TE Connectivity announced its 25 Gig-per-channel optical engine technology. The Coolbit optical engine will be included in four TE Connectivity products planned for this year: 100 Gig QSFP28 active optical cables (AOCs), 100 Gig QSFP28 transceivers, 300 Gig mid-board optical modules, and 400 Gig CDFP AOCs.
Meanwhile, Avago's MiniPod and MicroPod optical engine products now have a reach of 550m when coupled with Corning's ClearCurve OM4 fibre.
"This allows customers in the data centre to go a little bit further and not have to go to single-mode fibre," says Sharon Hall, product line manager for embedded optics at Avago.
For Part 1, click here
Further reading:-
TE Connectivity White Paper: End-to-end Communications with Fiber Optic Technologies, click here
LightCounting: Reflections on OFC 2014: The industry is approaching a critical junction, click here
Ovum at OFC 2014, click here
LightWave OFC 2014 Podcast, click here
Ethernet Alliance Blog: OFC 2014 show and best in class, click here
OFC 2014 industry reflections - Part 2
The high cost of 100 Gigabit Ethernet client modules has been a major disappointment to me as it has slowed adoption
Joe Berthold, Ciena
Joe Berthold, vice president of network architecture at Ciena.
OFC 2014 was another great event, with interesting programmes, demonstrations and papers presented. A few topics that really grabbed my interest were discussions around silicon photonics, software-defined networking (SDN) and 400 Gigabit Ethernet (GbE).
The intense interest we saw at last year’s OFC around silicon photonics grew this year with lots of good papers and standing-room-only sessions. I look forward to future product announcements that deliver on the potential of this technology to significantly reduce cost of interconnecting systems over modest distances. The high cost of 100GbE client modules has been a major disappointment to me as it has slowed adoption.
Another area of interest at this year’s show was the great deal of experimental work around SDN, some more practical than others.
I particularly liked the reviews of the latest work under the DARPA-sponsored CORONET programme, whose Phase 3 focused on SDN control of multi-layer, multi-vendor, multi-data centre cloud networking across wide area networks.
In particular, there were talks from three companies I noted: Anne Von Lehman of Applied Communication Sciences, the prime contractor, provided a good program overview; Bob Doverspike of AT&T described a very extensive testbed using equipment of the type currently deployed in AT&T’s network, as well as two different processing and storage virtualisation platforms; and Doug Freimuth of IBM described its contributions to CORONET including an OpenStack virtualisation environment, as well as other IBM distributed cloud networking research.
All the action on rates above 100 Gig lies with the selection of client signals. 400 Gig seems to have the major mindshare but there are still calls for flexible rate clients and Terabit clients.
One thing I enjoyed about these talks was that they described an approach to SDN for distributed data centre networking that is pragmatic and could be realised soon.
I also really liked a workshop held on the Sunday on the question whether SDN will kill GMPLS. While there was broad consensus that GMPLS has failed in delivering on its original turn-of-the-century vision of IP routers control of multi-layer, multi-domain networks, most speakers recognised the value distributed control planes have in simplifying and speeding the control of single layer, single domain networks.
What I took away was that single layer distributed control planes are here to stay as important network control functions, but instead will work under the direction of an SDN network controller.
As we all know, 400 Gigabit dense wavelength division multiplexing (DWDM) is here from the technology perspective, but awaiting standardisation of the 400 Gig Ethernet signal from the IEEE, and follow-on work by the ITU-T on signal mapping to OTN. In fact, from the perspective of DWDM transmission systems, 1 Terabit-per-second systems can be had for the asking.
All the action on rates above 100 Gig lies with the selection of client signals. 400 Gig seems to have the major mindshare but there are still calls for flexible rate clients and Terabit clients.
One area that received a lot of attention, with many differing points of view, was the question of the 400GbE client. As the 400GbE project begins soon in the IEEE, it is time to take a lesson from the history of the 100 Gig client modules and do better.
Let us all agree that we don’t need 400 Gig clients until they can do better in cost, face plate density, and power dissipation than the best 100 Gig modules that will exist then.
The first 100 Gig DWDM transceivers were introduced in 2009. It is now 2014 and 100 Gig is the transmission rate of choice for virtually all high capacity DWDM network applications, with a strong economic value proposition versus 10 Gig. Yet the industry has not yet managed to achieve cost/bit parity between 100 Gig and 10 Gig clients - far from it!
Last year's OFC, we saw many show floor demonstrations of CFP2 modules. They promise lower costs, but evidence of their presence in shipping products is still lacking. At the exhibit this year we saw 100 Gig QSFP28 modules. While progress is slow, the cost of the 100 Gig client module continues to result in many operators favouring 10 Gig handoffs to their 100 Gig optical networking systems.
Let us all agree that we don’t need 400 Gig clients until they can do better in cost, face plate density, and power dissipation than the best 100 Gig modules that will exist then. At this juncture the 100 Gig benchmark we should be comparing 400 Gig to is a QSFP28 package.
Lastly, last year we heard about the launch of an OIF project to create a pluggable analogue coherent optical module. There were several talks that referenced this project, and discussed its implications for shrinking size and supporting higher transceiver card density.
Broad adoption of this component will help drive down costs of coherent transceivers, so I look forward to its hearing about its progress at OFC 2015.
Daryl Inniss, vice president and practice leader, Ovum.
There was no shortage of client-side announcements at OFC and I’ve spent time since the conference trying to organise them and understand what it all means.
I’m tempted to say that the market is once again developing too many options and not quickly agreeing on a common solution. But I’m reminded that this market works collaboratively and the client-side uncertainty we’re seeing today is a reflection of a lack of market clarity.
Let me describe three forces affecting suppliers:
The IEEE 100GBASE-xxx standards represent the best collective information that suppliers have. Not surprisingly, most vendors brought solutions to OFC supporting these standards. Vendors sharpened their products and focused on delivering solutions with smaller form factors and lower power consumption. Advances in optical components (lasers, TOSAs and ROSAs), integrated circuits (CDRs, TIAs, drivers), transceivers, active optical cables, and optical engines were all presented. A promising and robust supply base is emerging that should serve the market well.
A second driver is that hyperscale service providers want a cost-effective solution today that supports 500m to 2km. This is non-standard and suppliers have not agreed on the best approach. This is where the market becomes fragmented. The same vendors supporting the IEEE standard are also pushing non-standard solutions. There are at least four different approaches to support the hyperscale request:
- Parallel single mode (PSM4) where an MSA was established in January 2014
- Coarse wavelength division multiplexing—using uncooled directly modulated lasers and single mode fibre
- Dense wavelength division multiplexing—this one just emerged on the scene at OFC with Ranovus and Mellanox introducing the OpenOptics MSA
- Complex modulation—PAM-8 for example and carrier multi-tone.
Admittedly, the presence of this demand disrupts the traditional process. But I believe the suppliers’ behavior reflects their unhappiness with the standardisation solution.
The good news is these approaches are using established form factors like the QSFP. And silicon photonic products are starting to emerge. Suppliers will continue to innovate.
Ambiguity will persist but we believe that clarity will ultimately prevail.
The third issue lurking in the background is knowledge that 400 Gig and one Terabit will soon be needed. The best-case scenario is to use 100 Gig as a platform to support the next generation. Some argue for complex modulation as you reduce the number of optical components thereby lowering cost. That’s good but part of the price is higher power consumption, an issue that is to be determined.
Part of today’s uncertainty is whether the standard solution is suitable to support the market to the next generation. Sixteen channels at 25 Gig is doable but feels more like a stopgap measure than a long-term solution.
These forces leave suppliers innovating in search of the best path forward. The approaches and solutions differ for each vendor. Timing is an issue too with hyperscale looking for solutions today while the mass market may be years away.
We believe that servers with 25 Gig and/ or 40 Gig ports will be one of the catalysts to drive the mass market and this will not start until about 2016. Meanwhile, each vendor and the market will battle for the apparent best solution to meet the varying demands. Ambiguity will persist but we believe that clarity will ultimately prevail.
OFC 2014 product round-up - Part 1
Part 1: Line-side technologies
Technologies for 100 Gigabit were prominent at this year's OFC conference and exhibition held in San Francisco earlier this month.
The transition to smaller pluggable modules – client-side CFP2, CFP4 and QSFP28 interfaces - was one 100 Gig trend, another was the first 100 Gig pluggable modules for metro and metro-regional networks. Acacia Communications detailed its low-power AC-100 CFP, while Oclaro demonstrated coherent optics in the smaller CFP2 pluggable module.
To fit within the CFP2, Oclaro has developed a transmitter that combines two tunable lasers (one being for the coherent receiver) and an indium phosphide modulator, and a micro intradyne coherent receiver (micro ICR).
Having 100 Gig coherent optics in a CFP2 will enable equipment makers to double the 100 Gig line ports on their platforms. The optics will also support polarisation multiplexed, 16-quadrature amplitude modulation (PM-16-QAM) and hence 200 Gig transmission. However, given the CFP2's limited power profile, the coherent DSP-ASIC will need to reside on the line card, external to the module. Oclaro says samples of its 'analogue CFP2' will be with customers from the second quarter of the year.
The same coherent optics will also be used for Oclaro's 100 Gig coherent CFP module. "If you combine the [transmitter and micro ICR] optics, you get the CFP2, and the power target is 12W," says Robert Blum, director, product management, 40 and 100 Gig line-side modules at Oclaro. "Combining the optics with a [coherent] DSP in the CFP, the power target is 32W, the highest CFP [power] class."
Oclaro's 100 Gig CFP will be available by year-end, coinciding with a new generation of merchant coherent DSP-ASIC designs. ClariPhy Communications is sampling its LightSpeed-II devices, implemented using a 28nm CMOS process, while NTT Electronics (NEL) is developing its next-generation DSP-ASIC, expected to use an even more advanced CMOS process.
Integrating the DSP chip and optics in a CFP simplifies a line card design and adds flexibility: the same CFP port can be used for line-side or client-side modules. But given that the coherent optics consumes 12W, the next-generation DSP-ASIC must consume no more than 18W typically, with the remaining 2W to accommodate the physical layer ICs, if the CFP's maximum power profile is not to be exceeded.
Acacia Communications' AC-100 coherent CFP module uses the company's DSP-ASIC and photonic integrated circuit (PIC) implemented using silicon photonics. The resulting 100 Gig CFP consumes 24-26W, well within the CFP's maximum 32W.
Meanwhile, Fujitsu Optical Components demonstrated all the components needed to make a 100 Gig coherent CFP, using its indium phosphide modulator to generate a 100 Gig polarisation multiplexed, quadrature phase-shift keying (PM-QPSK) signal, and a micro ICR.
Considering that the 5x7-inch Optical Internetworking Forum (OIF) multi-source agreement (MSA) 100 Gig transponder for long-haul consumes some 80W, with the DSP-ASIC alone consuming over half that, the advent of the coherent CFP and analogue CFP2 highlights the industry’s recent progress in shrinking the size and power consumption of coherent optics.
"Our focus long term is the CFP2. It is where we think the market is going to go in the next two years."
Ferris Lipscomb, NeoPhotonics
Coherent components
NeoPhotonics detailed an integrated coherent transmitter that combines a narrow-linewidth tunable laser and a PM-QPSK modulator in one package. The device joins NeoPhotonics' micro Integrable Tunable Laser Assembly (ITLA) and micro ICR that have already been announced. "These are the next generation, smaller form factor coherent optical components," says Ferris Lipscomb, vice president of marketing at NeoPhotonics. The transmitter supports PM-QPSK and PM-16-QAM such that it can be used for 100, 200 and even as an element to enable 400 Gig transmission.
The device is suited for line card, OIF MSA modules, and pluggable CFP and CFP2 designs. "Our focus long term is the CFP2," says Lipscomb. "It is where we think the market is going to go in the next two years." NeoPhotonics says its coherent devices has been sampling to customers and will be generally available in the second half of the year.
Oclaro announced that its micro ITLA, first detailed at ECOC 2013, now supports a flexible grid; the tunable laser's wavelength can be set independent of the ITU Grid spanning the C-band. Such a capability is required for advanced optical networks based on flexible-grid ROADMs and spectrally-efficient super-channels. "The flexible-grid micro ITLA gives peace of mind [to operators] even if it is not widely used yet," says Oclaro's Blum. The technology used for the micro ITLA is also used for Oclaro's CFP and CFP2 line side modules.
Fujitsu Optical Components announced a lithium niobate modulator that supports 100 Gig PM-QPSK and 400 Gig PM-xQAM signals. The new modulator has the same drive voltage as its existing 100 Gig lithium niobate modulator but is half the size. The company also announced an accompanying ICR that also supports 100 and 400 Gig transmissions in core networks. The company says both devices will be available from July.
Sumitomo Electric Industries detailed its micro ITLA at OFC. The micro ITLA uses a narrower line width laser and reduces power consumption by a fifth. The company also showcased a micro ICR that supports 100 and 200 Gig transmissions, and an indium phosphide based Mach-Zehnder modulator that is smaller and has lower power than a lithium niobate-based version.
Avago Technologies announced its micro ICR at OFC, a demonstration of Avago's broad component portfolio following its acquisition of CyOptics. Finisar was another company that showcased a new portfolio of high-speed optical components following its acquisition of u2t Photonics. These include indium phosphide-based Mach-Zehnder modulators and 100 Gig receivers and photodetectors.
Tunable SFP+
Both JDSU and Oclaro detailed their latest 10 Gigabit tunable SFP+ optical modules. Moving the tunable laser design from an XFP to the SFP+ has been a challenge, meeting the SFP+'s smaller dimensions and 1.5W power consumption.
Oclaro's latest tunable SFP+ now meets the 1.5W SFP+ specification. Oclaro says that to achieve the specification, it produced a more compact integrated laser Mach-Zehnder chip. Oclaro demonstrated the tunable SFP+ operating at 85oC. Beta samples of the tunable SFP+ are being shipped and the module will soon undergo qualification.
JDSU has had a tunable SFP+ product for over a year but its power consumption is 2W. The SFP+ length is also elongated by 4mm to fit the tunable laser. Now, JDSU has announced a revised design that no longer needs the extra 4mm and achieves a power consumption of 1.6W. "We will achieve the 1.5W specification in the near future," says Brandon Collings, JDSU's CTO for communications and commercial optical products.
"The reason why there is a lot of talk about hybrid EDFA-Raman in the industry is that it works very well with coherent."
Rafik Ward, Finisar
Pump lasers and hybrid amplifiers
JDSU also announced pump laser designs. The motivation for these latest pump products is the more demanding link budgets required for 100 Gig-and-greater transmission speeds while still achieving long-distance reaches.
JDSU announced Raman pump lasers for hybrid EDFA-Raman amplifiers. These are more power-efficient and cover the Raman pump wavelengths required, says JDSU: a 600mW output between 1425-1470nm and 550mW at 1470-1495nm. The company has also detailed higher-power 980nm pumps for EDFAs. "More power is almost always a good thing as it allows you a lot more design freedom and performance in your amp," says Collings.
Finisar demonstrated a hybrid EDFA-Raman amplifier for the first time. The hybrid amp is capable of spanning 220km and has a 44dB link loss. "The reason why there is a lot of talk about hybrid EDFA-Raman in the industry is that it works very well with coherent," says Rafik Ward, vice president of marketing at Finisar. Amplifier span distances of 80km are commonly used but the purpose of the demonstration was to showcase the product's capability, says Ward.
WSSes and multicast switches
NeoPhotonics has announced a modular multicast switch that allows an operator to grow a ROADM's node according to demand. The multicast switch is used to add colourless, directionless and contentionless (CDC) attributes to the ROADM. "You can have any wavelength [colourless] from any direction come out at any port [directionless]," says Lipscomb. "And if you have two identical wavelengths coming from different directions, you can drop them through the same switch [contentionless]."
Lipscomb cites as an example an 8-degree ROADM node, with each direction fibre carrying 100 dense WDM channels. Even if only a quarter of the channels are dropped, that is 200 channels, he says: "What we are announcing is a modular multicast switch; you can start with 4 channels and 4 drops and keep adding modular line cards as needed to add more drop ports and more directions."
NeoPhotonics modular multicast switches include such dimensions as 4x4, 4x16 and 8x16. "Carriers don't want to limit their future deployment but they also don't want to spend a lot of money now because they might want to drop 100 channels later," says Lipscomb.
JDSU announced its second-generation twin 1x20 wavelength-selective switch (WSS) that fits on a single-slot card. The twin WSS is used for advanced flexible-grid CDC-ROADM nodes.
The latest twin 1x20 WSS has the same functionality as JDSU's current twin 1x20 WSS that has been available for a year but which occupies two chassis slots. "It has the same capability but is considerably smaller," says Collings.
Indeed, the twin WSS is sufficiently compact that other functions can be added to the card such as amplification, optical power monitoring and optical service channels, communication channels between nodes used for such tasks as provisioning, power management and firmware updates.
For the OFC 2014 product round-up - Part 2, click here
ECOC 2013 review - Part 1
Gazettabyte surveys some of the notable product announcements made at the recent European Conference on Optical Communication (ECOC) held in London.
Part 1: Highlights
- First CFP4 module demonstration from Finisar
- Acacia Communications unveils first 100 Gig coherent CFP
- Oplink announces a 100 Gig direct detection CFP
- Second-generation coherent components take shape
100 Gigabit pluggables
Finisar used the ECOC exhibition to demonstrate the first CFP4 optical module, the smallest of the CFP MSA family of modules. The first CFP4 supports the 100GBASE-SR4 standard comprising four electrical and four optical channels, each at 25 Gigabit-per-second (Gbps).
The CFP4 is a quarter of the width of the CFP while the CFP2 is about a half the CFP's width. The CFP4 thus promises to quadruple the faceplate port density compared to using the CFP. Finisar says the CFP4 does even better, supporting line cards with 3.6 Terabits of capacity.
"It is not just the [CFP4's] width but the length and height that are shorter," says Rafik Ward, vice president of marketing at Finisar. The CFP4s can be aligned in two columns - belly-to-belly - on the card, achieving 3.6Tbps, each row comprising 18 CFP4 modules.
We see the CFP4 as a necessity to continue to grow the 100 Gigabit Ethernet market
The CFP4 was always scheduled to follow quickly the launch of the CFP2, says Ward. But the availability of the CFP4 will be important for the MSA. Data centre switch vendor Arista Networks has said that the CFP2 was late to market, while Cisco Systems has developed the CPAK, its own CFP2 alternative. "We see it [the CFP4] as a necessity to continue to grow the 100 Gigabit Ethernet market," says Ward.
Other 100 Gigabit Ethernet (GbE) variants will follow in the CFP4 form factor such as the LR4 and SR10 and the 10x10GbE breakout variant. This raises the interesting prospect of requiring an “inverse gearbox” chip that will translate between the CFP4's four electrical channels and the SR10's 10 optical channels. "We are going to see a lot of design activity around CFP4 in 2014," says Ward.
Meanwhile, Acacia Communications unveiled the AC-100, the first 100 Gig coherent CFP module for metro and regional networks, that includes a digital signal processor (DSP) system-on-chip.
"The DSP can be programmed for different performance and power levels to achieve a range of distances," says Daryl Inniss, vice president and practice leader components at market research firm, Ovum.
Acacia Communications says a CFP-based coherent design provides carriers and content providers with a 100 Gig metro solution that is more economical than 10 Gig.
Oplink Communications announced a direct detection 100 Gig metro CFP at ECOC. The 4x28Gbps CFP uses MultiPhy's maximum likelihood sequence estimation (MLSE) algorithm implemented using its MP1100Q and MP1101Q ICs. The devices enhance the reach of the module and allows 10 Gig optical components to be used for the receive and transmit paths. "Oplink’s CFP is the first module to come to market with our devices inside," says Neal Neslusan, vice president of marketing and sales at MultiPhy.
There are now at least three vendors selling direct-detection 100Gbps modules, says Neslusan, with Oplink and Menara Networks, which has also announced a CFP product, joining Finisar.
MultiPhy is working with several additional companies and that one system vendor will come to market with a product using the company's chips in the coming months. The company is also working on a second-generation direct detection IC design. "We believe there is a compelling roadmap story for direct detection," says Neslusan.
Oclaro announced it is now shipping in volume its 10km 100GBASE-LR4 CFP2 supporting 100GbE and OTU4 (OTN) rates. Oclaro has demonstrated the CFP2 working with a Xilinx Virtex 7 FPGA. "If customers choose that combination of technology, we have already tested it for them and they can rely on those rates [100GbE and OTU4] working," says Per Hansen, vice president of product marketing, optical networks solutions at Oclaro.
JDSU also said that its CFP2 LR4 is nearing completion. "We are getting pretty close to releasing it," says Brandon Collings, chief technology officer, communications and commercial optical products at JDSU.
Ed Murphy, JDSU
The integrated transmit and receive optical sub-assembly (TOSA/ ROSA) designs for the CFP2 LR4 use hybrid integration.
"In this case it is not monolithic integration as it is in the case of the indium phosphide line side modules but hybrid integration taking advantage of our PLC (planar lightwave circuit) technology in combination with arrays of photo detectors or high speed EMLs (externally modulated lasers)," says Murphy.
JDSU has based its module roadmap on the CFP2 TOSA and ROSA designs. The designs are sufficiently integrated to also fit within the QSFP28 and CFP4 modules.
There may be tweaks to the chips to lower the power dissipation, says Murphy, but these will be minor variants on existing parts.
Coherent components
Several component makers discussed their latest compact designs for next-generation coherent transmission line cards and modules.
NeoPhotonics detailed its micro-ITLA narrow linewidth tunable laser (micro-ITLA) that occupies less than a third of the area of the existing ITLA design. The company also announced a small form factor intradyne coherent receiver (SFF-ICR), less than half the size of existing integrated coherent receivers (ICRs).
NeoPhotonics supplies components to module and system vendors, and says customer interest in the second-generation coherent components is for higher port count line cards. "Instead of 100 Gig on a line card, you can have 200 or 400 Gigabit on a line card," says Ferris Lipscomb, vice president of marketing at NeoPhotonics. Moving to pluggable module designs will be a follow-on development, but for now, the market is not quite ready, he says.
An integrated coherent transmitter for metro, combining a tunable laser and integrated indium phosphide modulator in a compact package is also offered by NeoPhotonics.
The laser has two outputs - one output is modulated for the transmission while the second output is a local oscillator source feeding the coherent receiver. About half of all 100Gbps designs use such a split laser source, says Lipscomb, rather than two separate lasers, one each for the transmitter and the receiver. "That means that one transponder can only transmit and receive the same wavelength and is a little less flexible but for cost reduction that is what people are doing," says Lipscomb.
Oclaro is now sampling to customers its next-generation indium phosphide-based coherent components. The company, also a supplier of coherent modules, says the components will enable CFP and CFP2 pluggable coherent transceivers. The pluggable modules are suited for use in metro and metro regional networks.
Oclaro's components include an integrated transmitter comprising an indium phosphide laser and modulator, and the SFF-ICR. Oclaro's micro-ITLA is in volume production and has an output power high enough to perform both the transmit and the local oscillator functions. The micro-ITLA is used for line cards, 5x7-inch and 4x5-inch MSAs module and CFP designs.
u2t Photonics is another company that is developing a SFF-ICR. The company gave a private demonstration at ECOC to its customers of its indium phosphide modulator for use with CFP and CFP2 modules. "We demonstrated technical feasibility; it is a prototype which shows the capability of indium phosphide technology," says Jens Fiedler, executive vice president sales and marketing at u2t Photonics.
u2t Photonics and Finisar both licensed 100Gbps coherent indium phosphide modulator technology developed at the Fraunhofer Heinrich-Hertz-Institute.
There are new coherent DSP chips coming out early next year
Also showcased was u2t's gallium arsenide modulator technology implementing 16-QAM (quadrature amplitude modulation) at ECOC, but the company has yet to announce a product.
JDSU also gave an update on its line side coherent components. It is developing an integrated transmitter - a laser with nested modulators - for coherent applications. "This work is underway as a technology for line side CFP and CFP2 modules," says Ed Murphy, senior director, communications and commercial optical products at JDSU.
The difference between the CFP and CFP2 coherent modules is that the DSP system-on-chip is integrated within the CFP. Acacia's AC-100 CFP is the first example of such a product. For the smaller CFP2, the DSP will reside on the line card.
"There are new DSP [chips] coming out early next year," says Robert Blum, director of product marketing for Oclaro's photonic components. The DSPs will require a power consumption no greater than 20W if the complete design - the DSP and optics - is to comply with the CFP's maximum power rating of 32W.
Pluggable coherent modules promise greater port densities per line card. The modules can also be deployed with traffic demand and, in the case of a fault, can be individually swapped rather than having to replace the line card, says Blum.
JDSU says two factors are driving the metro coherent market. One is the need for lower cost designs to meet metro's cost-sensitive requirements. The second is that the metro distances can use essentially the same devices for 16-QAM to support 200Gbps links as well as 100Gbps. "It is the same modulator structure; maybe a few of the specs are a bit tighter but you can think of it as the same device," says Murphy.
System vendors have trialled 200Gbps links but deployments are expected to start from 2014. The deployments will likely use lithium niobate modulators, says Murphy, but will be followed quickly by indium phosphide designs.
NeoPhotonics used ECOC to declare that it has now integrated the semiconductor optical component arm of Lapis Semiconductor which it acquired for $35.2 million in March 2013.
Ferris Lipscomb
The unit, known as NeoPhotonics Semiconductor GK, makes drivers and externally modulated lasers. "These are key technologies for high-speed 100 Gig and 400 Gig transmissions, both on the line side and on the client side," says Lipscomb.
NeoPhotonics, previously a customer of Lapis, decided to acquire the unit and benefit from vertical integration as it expands its 100 Gig and higher-speed coherent portfolio.
Owning the technology has cost and optical performance benefits, says Lipscomb. It enables the integration of a design on one chip, thereby avoiding interfacing issues.
Further reading:
Part 2, click here
Hybrid integration specialist Kaiam acquires Gemfire
Kaiam Corp. has secured US $16M in C-round funding and completed the acquisition of Gemfire.
"We have a micro-machine technology that allows us to use standard pick-and-place electronic assembly tools, and with our micro-machine, we achieve sub-micron alignment tolerances suitable for single-mode applications"
Byron Trop, Kaiam
With the acquisition, Kaiam gains planar lightwave circuit (PLC) technology and Gemfire's 8-inch wafer fab in Scotland. This is important for the start-up given there are few remaining independent suppliers of PLC technology.
Working with Oplink Communications, Kaiam has also demonstrated recently a 100 Gigabit 10x10 MSA 40km CFP module.
Hybrid integration technology
Kaiam has developed hybrid integration technology that achieves sub-micron alignment yet only requires standard electronic assembly tools.
"With single-mode optics, it is very, very difficult to couple light between components," says Byron Trop, vice president of marketing and sales at Kaiam. "Most of the cost in our industry is associated with aligning components, testing them and making sure everything works."
The company has developed a micro-machine-operated lens that is used to couple optical components. The position of the lens is adjustable such that standard 'pick-and-place' manufacturing equipment with a placement accuracy of 20 microns can be used. "If you set everything [optical components] up in a transceiver with a 20-micron accuracy, nothing would work," says Trop.
Components are added to a silicon breadboard and the micro-machine enables the lens to be moved in three dimensions to achieve sub-micron alignment. "We have the ability to use coarse tools to manipulate the machine, and at the far end of that machine we have a lens that is positioned to sub-micron levels," says Trop. Photo-diodes on a PLC provide the feedback during the active alignment.
Another advantage of the technique is that any movement when soldering the micro-machine in position has little impact on the lens alignment. "Any movement that happens following soldering is dampened over the distance to the lens," says Trop. "Therefore, movement during the soldering process has negligible impact on the lens position."
Kaiam buys its lasers and photo-detector components, while a fab make its micro-machine. Hybrid integration is used to combine the components for its transmitter optical sub-assembly (TOSA) and receiver optical sub-assembly (ROSA) designs, and these are made by contract manufacturers. Kaiam has a strategic partnership with contract manufacturer, Sanmina-SCI.
The company believes that by simplifying alignment, module and systems companies have greater freedom in the channel count designs they can adopt. "Hybrid integration, this micro-alignment of optical components, is no longer a big deal," says Trop. "You can start thinking differently."
"We will also do more custom optical modules where somebody is trying to solve a particular problem; maybe they want 16 or 20 lanes of traffic"
For 100 Gigabit modules, companies have adopted 10x10 Gigabit-per-second (Gbps) and 4x28Gbps designs. The QSFP28 module, for example, has enabled vendors to revert back to four channels because of the difficulties in assembly.
"Our message is not more lanes is better," says Trop. "Rather, what is the application and don't consider yourself limited because the alignment of sub-components is a challenge."
With the Gemfire acquisition, Kaiam has its own PLC technology for multiplexing and de-multiplexing multiple 10Gbps and, in future, 25Gbps lanes. "Our belief is that PLC is the best way to go and allows you to expand into larger lane counts," says Trop.
Gemfire also owned intellectual property in the areas of polymer waveguides and semiconductor optical amplifiers.
Products and roadmap
Kaiam sells 40Gbps QSFP TOSAs and ROSAs for 2km, 10km and 40km reaches. The company is now selling its 40km 10x10 MSA TOSA and ROSA demonstrated at the recent OFC/NFOEC show. Trop says that the 40km 10x10 CFP MSA module is of great interest to Internet exchange operators that want low cost, point-to-point links.
"Low cost, highly efficient optical interconnect is going to be important and it is not all at 40km reaches," says Trop. "Much of it is much shorter distances and we believe we have a technology that will enable that."
The company is looking to apply its technology to next-generation optical modules such as the CFP2, CFP4 and QSFP28. "We will also do more custom optical modules where somebody is trying to solve a particular problem; maybe they want 16 or 20 lanes of traffic," says Trop.
Luxtera's interconnect strategy
Part 1: Optical interconnect
Luxtera demonstrated a 100 Gigabit QSFP optical module at the OFC/NFOEC 2013 exhibition.
"We're in discussions with a lot of memory vendors, switch vendors and different ASIC providers"
Chris Bergey, Luxtera
The silicon photonics-based QSFP pluggable transceiver was part of the Optical Internetworking Forum's (OIF) multi-vendor demonstration of the 4x25 Gigabit chip-to-module interface, defined by the CEI-28G-VSR Implementation Agreement.
The OIF demonstration involved several optical module and chip companies and included CFP2 modules running the 100GBASE-LR4 10km standard alongside Luxtera's 4x28 Gigabit-per-second (Gbps) silicon photonics-based QSFP28.
Kotura also previewed a 100Gbps QSFP at OFC/NFOEC but its silicon photonics design uses two chips and wavelength-division multiplexing (WDM).
The Luxtera QSFP28 is being aimed at data centre applications and has a 500m reach although Luxtera says up to 2km is possible. The QSFP28 is sampling to initial customers and will be in production next year.
100 Gigabit modules
Current 100GBASE-LR4 client-side interfaces are available in the CFP form factor. OFC/NFOEC 2013 saw the announcement of two smaller pluggable form factors at 100Gbps: the CFP2, the next pluggable on the CFP MSA roadmap, and Cisco Systems' in-house CPAK.
Now silicon photonics player Luxtera is coming to market with a QSFP-based 100 Gigabit interface, more compact than the CFP2 and CPAK.
The QSFP is already available as a 40Gbps interface. The 40Gbps QSFP also supports four independent 10Gbps interfaces. The QSFP form factor, along with the SFP+, are widely used on the front panels of data centre switches.
"The QSFP is an inside-the-data-centre connector while the CFP/CFP2 is an edge of the data centre, and for telecom, an edge router connector," says Chris Bergey, vice president of marketing at Luxtera. "These are different markets in terms of their power consumption and cost."
Bergey says the big 'Web 2.0' data centre operators like the reach and density offered by the 100Gbps QSFP as their data centres are physically large and use flatter, less tiered switch architectures.
"If you are a big systems company and you are betting on your flagship chip, you better have multiple sources"
The content service providers also buy transceivers in large volumes and like that the Luxtera QSFP works over single-mode fibre which is cheaper than multi-mode fibre. "All these factors lead to where we think silicon photonics plays in a big way," says Bergey.
The 100Gbps QSFP must deliver a lower cost-per-bit compared to the 40Gbps QSFP if it is to be adopted widely. Luxtera estimates that the QSFP28 will cost less than US $1,000 and could be as low as $250.
Optical interconnect
Luxtera says its focus is on low-cost, high-density interconnect rather than optical transceivers. "We want to be a chip company," says Bergey.
The company defines optical interconnect as covering active optical cable and transceivers, optical engines used as board-mounted optics placed next to chips, and ASICs with optical SerDes (serialiser/ deserialisers) rather than copper ones.
Optical interconnect, it argues, will have a three-stage evolution: starting with face-plate transceivers, moving to mid-board optics and then ASICS with optical interfaces. Such optical interconnect developments promise lower cost high-speed designs and new ways to architect systems.
Currently optics are largely confined to transceivers on a system׳s front panel. The exceptions are high-end supercomputer systems and emerging novel designs such as Compass-EOS's IP core router.
"The problem with the front panel is the density you can achieve is somewhat limited," says Bergey. Leading switch IC suppliers using a 40nm CMOS process are capable of a Terabit of switching. "That matches really well if you put a ton of QSFPs on the front panel," says Bergey.
But once switch IC vendors use the next CMOS process node, the switching capacity will rise to several Terabits. This becomes far more challenging to meet using front panel optics and will be more costly compared to putting board-mounted optics alongside the chip.
"When we build [silicon photonics] chips, we can package them in QSFPs for the front panel, or we can package them for mid-board optics," says Bergey.
"If it [silicon photonics] is viewed as exotic, it is never going to hit the volumes we aspire to."
The use of mid-board optics by system vendors is the second stage in the evolution of optical interconnect. "It [mid-board optics] is an intermediate step between how you move from copper I/O [input/output] to optical I/O," says Bergey.
The use of mid-board optics requires less power, especially when using 25Gbps signals, says Bergey: “You dont need as many [signal] retimers.” It also saves power consumed by the SerDes - from 2W for each SerDes to 1W, since the mid-board optics are closer and signals need not be driven all the way to the front panel. "You are saving 2W per 100 Gig and if you are doing several Terabits, that adds up," says Bergey.
The end game is optical I/O. This will be required wherever there are dense I/O requirements and where a lot of traffic is aggregated.
Luxtera, as a silicon photonics player, is pursuing an approach to integrate optics with VLSI devices. "We're in discussions with a lot of memory vendors, switch vendors and different ASIC providers," says Bergey.
Silicon photonics fab
Last year STMicroelectronics (ST) and Luxtera announced they would create a 300mm wafer silicon photonics process at ST's facility in Crolles, France.
Luxtera expects that line to be qualified, ramped and in production in 2014. Before then, devices need to be built, qualified and tested for their reliability.
"If you are a big systems company and you are betting on your flagship chip, you better have multiple sources," says Bergey. "That is what we are doing with ST: it drastically expands the total available market of silicon photonics and it is something that ST and Luxtera can benefit from.”
Having multiple sources is important, says Bergey: "If it [silicon photonics] is viewed as exotic, it is never going to hit the volumes we aspire to."
Part 2: Bell Labs on silicon photonics click here
Part 3: Is silicon photonics an industry game-changer? click here