Open Eye MSA offers an alternative to PAM-4 DSPs

A group of companies, led by Macom and Semtech, have launched a multi-source agreement (MSA) to offer an alternative to using a digital signal processor (DSP) in high-speed client-side optical modules. 

The Open Eye MSA is developing a set of specifications for optical modules that use 50-gigabit 4-level pulse-amplitude modulation (PAM-4) signals whereby only analogue clock and data recovery (CDR) circuitry is required at the receiver.  

By using the CDR instead of a PAM-4 DSP, the optical module will consume less power, have lower latency and be less costly to make, says the MSA.

To ensure interoperability, however, module makers using a PAM-4 DSP will need to meet the new MSA specification. 

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Ciena to sell its own coherent modules

The systems vendor is expanding its offerings to include WaveLogic modem chips and coherent optical modules.

Ciena is developing its own coherent modules to sell to the telecom and datacom markets. 

The system vendor has set up the Optical Microsystems Division business unit to promote its WaveLogic coherent modem technology to the marketplace. Until now it has licensed its WaveLogic Ai digital signal processor (DSP) to module makers Lumentum, NeoPhotonics and Oclaro. But now it is planning to sell its own coherent modules.

In a job advert for a head of sales channel development, Ciena says the Optical Microsystems Division's goal is ‘to develop and productize electro-optic components and modules for sale to global systems integrator customers to be incorporated in their products for sale to telecom and data network customers’.

And at the recent European Conference on Optical Communication (ECOC) held in Rome, a network equipment manufacturer said it was approached by Ciena enquiring if it was interested in buying coherent modules from the company.

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Optical module trends: A conversation with Finisar

Finisar demonstrated recently a raft of new products that address emerging optical module developments. These include: 

• A compact coherent integrated tunable transmitter and receiver assembly 
• 400GBASE-FR8 and -LR8 QSFP-DD pluggable modules and a QSFP-DD active optical cable 
• A QSFP28 100-gigabit serial FR interface 
• 50-gigabit SFP56 SR and LR modules

Rafik Ward, Finisar’s general manager of optical interconnects, explains the technologies and their uses.

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COBO issues industry’s first on-board optics specification

• COBO modules supports 400-gigabit and 800-gigabit data rates   
• Two electrical interfaces have been specified: 8 and 16 lanes of 50-gigabit PAM-4 signals. 
• There are three module classes to support designs ranging from client-slide multi-mode to line-side coherent optics. 
• COBO on-board optics will be able to support 800 gigabits and 1.6 terabits once 100-gigabit PAM-4 electrical signals are specified. 

Source: COBO

Interoperable on-board optics has moved a step closer with the publication of the industry’s first specification by the Consortium for On-Board Optics (COBO).

COBO has specified modules capable of 400-gigabits and 800-gigabits rates. The designs will also support 800-gigabit and 1.6-terabit rates with the advent of 100-gigabit single-lane electrical signals. 

“Four hundred gigabits can be solved using pluggable optics,” says Brad Booth, chair of COBO and principal network architect for Microsoft’s Azure Infrastructure. “But if I have to solve 1.6 terabits in a module, there is nothing out there but COBO, and we are ready.”

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DustPhotonics reveals its optical transceiver play

A start-up that has been active for a year has dropped its state of secrecy to reveal it is already shipping its first optical transceiver product.

The company, DustPhotonics, is backed by private investors and recently received an undisclosed round of funding that will secure the company’s future for the next two years.  

Product plans

DustPhotonics' first product is the multi-mode 100m-reach 100GBASE-SR4 QSFP28. The company will launch its first 400-gigabit optical modules later this year. 

Ben Rubovitch

“We probably are going to be one of the first to market with [400-gigabit] QSFP-DD and OSFP multi-mode solutions,” says Ben Rubovitch, CEO of DustPhotonics.

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Finisar's 10 Gig bi-directional DWDM architecture

Finisar has developed a bi-directional 10-gigabit SFP+ module for the metro-access market. The dense wavelength-division multiplexing (DWDM) module is designed to expand capacity at locations where fibre is scarce. And being tunable, the SFP+ also simplifies network planning for the operators.

Finisar demonstrated the module working at the recent ECOC 2017 show held in Gothenburg.

Market applications

Interest is growing in using WDM optics for wireless, metro-access and cable networks that are undergoing upgrades. The interest in WDM at the network edge is due to a need to use fibre resources more efficiently. “We are seeing that globally, more and more dark fibre is being used up,” says Leo Lin, director of product line management at Finisar.

Leo LinGiven the cost of leasing and installing fibre, operators are keen to make the best use of their existing fibre and are willing to pay more for WDM optics.

According to Finisar, leasing a fibre can cost $250-$2,000 per fibre annually while the cost of installing fibre can be $500,000 per 10km. “Using WDM optics, you can get payback in less than a year,” says Lin.

LightCounting Market Research's latest forecast estimates that the global wireless transceiver market for 10 gigabit WDM will be approximately $400 million in 2022.

Finisar’s bi-directional 10-gigabit SFP+ product is also being aimed at two emerging ITU Telecom standards: G.metro and NG-PON2. 

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The many paths to 400 gigabits

The race is on to deliver 400-gigabit optical interfaces in time for the next-generation of data centre switches expected in late 2018.

The industry largely agrees that a four-wavelength 400-gigabit optical interface is most desirable yet alternative designs are also being developed.

Optical module makers must consider such factors as technical risk, time-to-market and cost when choosing which design to back.

Rafik Ward, FinisarUntil now, the industry has sought a consensus on interfaces, making use of such standards bodies as the IEEE to serve the telecom operators.

Now, the volumes of modules used by the internet giants are such that they dictate their own solutions. And the business case for module makers is sufficiently attractive that they are willing to comply.

Another challenge at 400 gigabits is that there is no consensus regarding what pluggable form factor to use. 

“There is probably more technical risk in 400 gigabits than any of the historical data-rate jumps we have seen,” says Rafik Ward, vice president of marketing at Finisar.

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