Talking markets: Oclaro on 100 gigabits and beyond
Oclaro’s chief commercial officer, Adam Carter, discusses the 100-gigabit market, optical module trends, silicon photonics, and why this is a good time to be an optical component maker.
Oclaro has started its first quarter 2017 fiscal results as it ended fiscal year 2016 with another record quarter. The company reported revenues of $136 million in the quarter ending in September, 8 percent sequential growth and the company's fifth consecutive quarter of 7 percent or greater revenue growth.
Adam CarterA large part of Oclaro’s growth was due to strong demand for 100 gigabits across the company’s optical module and component portfolio.
The company has been supplying 100-gigabit client-side optics using the CFP, CFP2 and CFP4 pluggable form factors for a while. “What we saw in June was the first real production ramp of our CFP2-ACO [coherent] module,” says Adam Carter, chief commercial officer at Oclaro. “We have transferred all that manufacturing over to Asia now.”
The CFP2-ACO is being used predominantly for data centre interconnect applications. But Oclaro has also seen first orders from system vendors that are supplying US communications service provider Verizon for its metro buildout.
The company is also seeing strong demand for components from China. “The China market for 100 gigabits has really grown in the last year and we expect it to be pretty stable going forward,” says Carter. LightCounting Market Research in its latest optical market forecast report highlights the importance of China’s 100-gigabit market. China’s massive deployments of FTTx and wireless front haul optics fuelled growth in 2011 to 2015, says LightCounting, but this year it is demand for 100-gigabit dense wavelength-division multiplexing and 100 Gigabit Ethernet optics that is increasing China’s share of the global market.
The China market for 100 gigabits has really grown in the last year and we expect it to be pretty stable going forward
QSFP28 modules
Oclaro is also providing 100-gigabit QSFP28 pluggables for the data centre, in particular, the 100-gigabit PSM4 parallel single-mode module and the 100-gigabit CWDM4 based on wavelength-division multiplexing technology.
2016 was expected to be the year these 100-gigabit optical modules for the data centre would take off. “It has not contributed a huge amount to date but it will start kicking in now,” says Carter. “We always signalled that it would pick up around June.”
One reason why it has taken time for the market for the 100-gigabit QSFP28 modules to take off is the investment needed to ramp manufacturing capacity to meet the demand. “The sheer volume of these modules that will be needed for one of these new big data centres is vast,” says Carter. “Everyone uses similar [manufacturing] equipment and goes to the same suppliers, so bringing in extra capacity has long lead times as well.”
Once a large-scale data centre is fully equipped and powered, it generates instant profit for an Internet content provider. “This is very rapid adoption; the instant monetisation of capital expenditure,” says Carter. “This is a very different scenario from where we were five to ten years ago with the telecom service providers."
Data centre servers and their increasing interface speed to leaf switches are what will drive module rates beyond 100 gigabits, says Carter. Ten Gigabit Ethernet links will be followed by 25 and 50 Gigabit Ethernet. “The lifecycle you have seen at the lower speeds [1 Gigabit and 10 Gigabit] is definitely being shrunk,” says Carter.
Such new speeds will spur 400-gigabit links between the data centre's leaf and spine switches, and between the spine switches. “Two hundred Gigabit Ethernet may be an intermediate step but I’m not sure if that is going to be a big volume or a niche for first movers,” says Carter.
400 gigabit CFP8
Oclaro showed a prototype 400-gigabit module in a CFP8 module at the recent ECOC show in September. The demonstrator is an 8-by-50 gigabit design using 25 gigabaud optics and PAM-4 modulation. The module implements the 400Gbase-LR8 10km standard using eight 1310nm distributed feedback lasers, each with an integrated electro-absorption modulator. The design also uses two 4-wide photo-detector arrays.
“We are using the four lasers we use for the CWDM4 100-gigabit design and we can show we have the other four [wavelength] lasers as well,” says Carter.
Carter says IP core routers will be the main application for the 400Gbase-LR8 module. The company is not yet saying when the 400-gigabit CFP8 module will be generally available.
We can definitely see the CFP2-ACO could support 400 gigabits and above
Coherent
Oclaro is already working with equipment customers to increase the line-side interface density on the front panel of their equipment.
The Optical Internetworking Forum (OIF) has already started work on the CFP8-ACO that will be able to support up to four wavelengths, each supporting up to 400 gigabits. But Carter says Oclaro is working with customers to see how the line-side capacity of the CFP2-ACO can be advanced. “We can definitely see the CFP2-ACO could support 400 gigabits and above,” says Carter. “We are working with customers as to what that looks like and what the schedule will be.”
And there are two other pluggable form factors smaller than the CFP2: the CFP4 and the QSFP28. “Will you get 400 gigabits in a QSFP28? Time will tell, although there is still more work to be done around the technology building blocks,” says Carter.
Vendors are seeking the highest aggregate front panel density, he says: “The higher aggregate bandwidth we are hearing about is 2 terabits but there is a need to potentially going to 3.2 and 4.8 terabits.”
Silicon photonics
Oclaro says it continues to watch closely silicon photonics and to question whether it is a technology that can be brought in-house. But issues remain. “This industry has always used different technologies and everything still needs light to work which means the basic III-V [compound semiconductor] lasers,” says Carter.
“Producing silicon photonics chips versus producing packaged products that meet various industry standards and specifications are still pretty challenging to do in high volume,” says Carter. And integration can be done using either silicon photonics or indium phosphide. “My feeling is that the technologies will co-exist,” says Carter.
600-gigabit channels on a fibre by 2017
NeoPhotonics has announced an integrated coherent receiver that will enable 600-gigabit optical transmission using a single wavelength. A transmission capacity of 48 terabits over the fibre’s C-band is then possible using 80 such channels.
NeoPhotonics’ micro integrated coherent receiver operates at 64 gigabaud, twice the symbol rate of deployed 100-gigabit optical transport systems and was detailed at the recent ECOC show.
Current 100 gigabit-per-second (Gbps) coherent systems use polarisation-multiplexing, quadrature phase-shift keying (PM-QPSK) modulation operating at 32 gigabaud. “That is how you get four bits [per symbol],” says Ferris Lipscomb, vice president of marketing at NeoPhotonics.
Optical designers have two approaches to increase the data transmitted on a wavelength: they can use increasingly complex modulation schemes - such as 16 quadrature amplitude modulation (16-QAM) or 64-QAM - and they can increase the baud rate. “You double the baud rate, you double the transmission capacity,” says Lipscomb. “And using 64-QAM and 64 gigabaud, you can go to 600 gigabit per channel; of course when you do that, you reduce the reach.”
The move to the higher 64 gigabaud symbol rate will help Internet content providers increase capacity between their large-scale data centres. Typical transmission distances between sites are relatively short, up to 100km.
Telcos too will benefit from the higher baud rate as it will enable them to use software-defined networking to adapt, on-the-fly, a line card’s data rate and reach depending on the link. Such a flexible rate coherent line card would allow 600Gbps on a single channel over 80km, 400 gigabit (16-QAM) over 400km, or 100 gigabit over thousands of kilometers.
Status
NeoPhotonics says it is now sampling its 64 gigabaud coherent receiver. It is still premature to discuss when the high-speed coherent receiver will be generally available, the company says, as it depends on the availability of other vendors’ components working at 64 gigabaud. These include the modulator, the trans-impedance amplifier and the coherent digital signal processor ASIC (DSP-ASIC).
Lipscomb says that a 64-gigabaud modulator in lithium niobate already exists but not in indium phosphide. The lithium niobate modulator is relatively large and will fit within a CFP module but the smaller CFP2 module will require a 64-gigabaud indium phosphide modulator.
“General availability will be timed based on when our customers are ready to go into production,” says Lipscomb. “Trials will happen in the first half of 2017 with volume shipments only happening in the second half of next year.”
Using 64-QAM and 64 gigabaud, you can go to 600 gigabit per channel
Challenges
A micro integrated coherent receiver has two inputs - the received optical signal and the local oscillator - and four balanced receiver outputs. Also included are two polarisation beam splitters and two 90-degree hybrid mixers.
Lipscomb says Neophotonics worked for over a year to develop its coherent receiver: “It is a complete design from the ground up.”
The slowest element sets the speed at which the receiver can operator such that the design not only involves the detector and trans-impedance amplifier but other elements such as the wirebonds and the packaging. “Everything has to be upgraded,” says Lipscomb. “It is not just a case of plopping in a faster detector and everything works.”
Nano-ICR and the CFP2-DCO
The industry is now working on a successor, smaller coherent detector dubbed the nano integrated coherent receiver (nano-ICR). “It has not all gelled yet but the nano-ICR would be suitable for the CFP2-DCO.”
The CFP2-DCO is a CFP2 Digital Coherent Optics pluggable module that integrates the coherent DSP-ASIC. In contrast, the CFP2 Analog Coherent Optics (CFP2-ACO) modules holds the optics and the DSP-ASIC resides on the line card.
“As the new DSPs come out using the next CMOS [process] nodes, they will be lower power and will be accommodated in the CFP2 form factor,” says Lipscomb. “Then the optics has to shrink yet again to make room for the DSP.”
Lipscomb sees the CFP2-ACO being used by system vendors that have already developed their own DSP-ASICs and will offer differentiated, higher-transmission performance. The CFP2-DCO will be favoured for more standard deployments and by end-customers that do not want to be locked into a single vendor and a proprietary DSP.
There is also the CFP2-DCO’s ease of deployment. In China, currently undertaking large-scale 100-gigabit optical transport deployments, operators want a module that can be deployed in the field by a relatively unskilled technician. “The ACOs with the analogue interface tend to require a lot of calibration,” says Lipscomb. “You can’t just plug it in and it works; you have to run it in, calibrate it and bring it up to get it to work properly.”
The CFP2-DCO module is expected in 2018 as the DSP-ASICs will require an advanced 12nm or even 7nm CMOS process.
Ranovus shows 200 gigabit direct detection at ECOC
Ranovus has announced it first direct-detection optical products for applications including data centre interconnect.
Saeid AramidehThe start-up has announced two products to coincide with this week’s ECOC show being held in Dusseldorf, Germany.
One product is a 200 gigabit-per-second (Gbps) dense wavelength-division multiplexing (WDM) CFP2 pluggable optical module that spans distances up to 130km. Ranovus will also sell the 200Gbps transmitter and receiver optical engines that can be integrated by vendors onto a host line card.
The dense WDM direct-detection solution from Ranovus is being positioned as a cheaper, lower-power alternative to coherent optics used for high-capacity metro and long-haul optical transport. Using such technology, service providers can link their data centre buildings distributed across a metro area.
The cost [of the CFP2 direct detection] proves in much better than coherent
“The power consumption [of the direct-detection design] is well within the envelope of what the CFP2 power budget is,” says Saeid Aramideh, a Ranovus co-founder and chief marketing. The CFP2 module's power envelop is rated at 12W and while there are pluggable CFP2-ACO modules now available, a coherent DSP-ASIC is required to work alongside the module.
“The cost [of the CFP2 direct detection] proves in much better than coherent does,” says Aramideh, although he points out that for distances greater than 120km, the economics change.
The 200Gbps CFP2 module uses four wavelengths, each at 50Gbps. Ranovus is using 25Gbps optics with 4-level pulse-amplitude modulation (PAM-4) technology provided by fabless chip company Broadcom to achieve the 50Gbps channels. Up to 96, 50 Gbps channels can be fitted in the C-band to achieve a total transmission bandwidth of 4.8 terabits.
Ranovus is demonstrating at ECOC eight wavelengths being sent over 100km of fibre. The link uses a standard erbium-doped fibre amplifier and the forward-error correction scheme built into PAM-4.
Technologies
Ranovus has developed several key technologies for its proprietary optical interconnect products. These include a multi-wavelength quantum dot laser, a silicon photonics based ring-resonator modulator, an optical receiver, and the associated driver and receiver electronics.
The quantum dot technology implements what is known as a comb laser, producing multiple laser outputs at wavelengths and grid spacings that are defined during fabrication. For the CFP2, the laser produces four wavelengths spaced 50GHz apart.
For the 200Gbps optical engine transmitter, the laser outputs are fed to four silicon photonics ring-resonator modulators to produce the four output wavelengths, while at the receiver there is an equivalent bank of tuned ring resonators that delivers the wavelengths to the photo-detectors. Ranovus has developed several receiver designs, with the lower channel count version being silicon photonics based.
The quantum dot technology implements what is known as a comb laser, producing multiple laser outputs at wavelengths and grid spacings that are defined during fabrication.
The use of ring resonators - effectively filters - at the receiver means that no multiplexer or demultiplexer is needed within the optical module.
“At some point before you go to the fibre, there is a multiplexer because you are multiplexing up to 96 channels in the C-band,” says Aramideh. “But that multiplexer is not needed inside the module.”
Company plans
The startup has raised $35 million in investment funding to date. Aramideh says the start-up is not seeking a further funding round but he does not rule it out.
The most recent funding round, for $24 million, was in 2014. At the time the company was planning to release its first product - a QSFP28 100-Gigabit OpenOptics module - in 2015. Ranovus along with Mellanox Technologies are co-founders of the dense WDM OpenOptics multi-source agreement that supports client side interface speeds at 100Gbps, 400Gbps and terabit speeds.
However, the company realised that 100-gigabit links within the data centre were being served by the coarse WDM CWDM4 and CLR4 module standards, and it chose instead to focus on the data centre interconnect market using its direct detection technology.
Ranovus has also been working with ADVA Optical Networking with it data centre interconnect technology. Last year, ADVA Optical Networking announced its FSP 3000 CloudConnect data centre interconnect platform that can span both the C- and L-bands.
Also planned by Ranovus is a 400-gigabit CFP8 module - which could be a four or eight channel design - for the data centre interconnect market.
Meanwhile, the CFP2 direct-detection module and the optical engine will be generally available from December.