OIF starts work on a terabit-plus CFP8-ACO module

The Optical Internetworking Forum (OIF) has started a new analogue coherent optics (ACO) specification based on the CFP8 pluggable module.

The CFP8 is the latest is a series of optical modules specified by the CFP Multi-Source Agreement and will support the emerging 400 Gigabit Ethernet standard.

Karl GassAn ACO module used for optical transport integrates the optics and driver electronics while the accompanying coherent DSP-ASIC residing on the line card.

Systems vendors can thus use their own DSP-ASIC, or a merchant one if they don’t have an in-house design, while choosing the coherent optics from various module makers. The optics and the DSP-ASIC communicate via a high-speed electrical connector on the line card.

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NeoPhotonics showcases a CFP2-ACO roadmap to 400G

NeoPhotonics has begun sampling its CFP2-ACO, a pluggable module for metro and long-haul optical transport. 

The company demonstrated the CFP2-ACO module transmitting at 100 gigabit using polarisation multiplexed, quadrature phase-shift keying (PM-QPSK) modulation at the recent OFC show. The line-side module is capable of transmitting over 1,000km and also supports PM-16QAM that doubles capacity over metro network distances.

Ferris LipscombThe CFP2-ACO is a Class 3 design: the control electronics for the modulator and laser reside on the board, alongside the coherent DSP-ASIC chip.

At OFC, NeoPhotonics also demonstrated single-wavelength 400-gigabit transmission using more advanced modulation and a higher symbol rate, and a short-reach 100-gigabit link for inside the data centre using 4-level pulse-amplitude modulation (PAM4) signalling. 

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OIF document aims to spur line-side innovation

The Optical Internetworking Forum (OIF) has completed defining the CFP2-ACO (analogue coherent optics) module, used for coherent-based optical transmission. The industry body's CFP2-ACO Implementation Agreement document has been developed to help optical component vendors bring innovative line-side products to market more quickly.

The CFP2-ACO. Source: OIF

The pluggable CFP2-ACO houses the coherent optics, known as the analogue front end. The components include the tuneable lasers, modulation, coherent receiver, and the associated electronics - the drivers and the trans-impedance amplifier. The Implementation Agreement also includes the CFP2-ACO's high-speed electrical interface connecting the optics to the coherent DSP chip that sits on the line card.

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Arista adds coherent CFP2 modules to its 7500 switch

Arista Networks has developed a coherent optical transport line card for its 7500 high-end switch series. The line card hosts six 100 gigabit CFP2-ACO (analogue coherent optics) and has a reach of up to 5,000 km.

Martin Hull

Several optical equipment makers have announced ‘stackable’ platforms specifically to link data centres in the last year.

Infinera’s Cloud Xpress was the first while Coriant recently detailed its Groove G30 platform. Arista’s announcement offers data centre managers an alternative to such data centre interconnect platforms by adding dense wavelength-division multiplexing (DWDM) optics directly onto its switch. 

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COBO looks inside and beyond the data centre

The Consortium of On-Board Optics is working on 400 gigabit optics for the data centre and also for longer-distance links. COBO is a Microsoft-led initiative tasked with standardising a form factor for embedded optics.

Established in March 2015, the consortium already has over 50 members and expects to have early specifications next year and first hardware by late 2017.

Brad Booth

Brad Booth, the chair of COBO and principal architect for Microsoft’s Azure Global Networking Services, says Microsoft plans to deploy 100 gigabit in its data centres next year and that when the company started looking at 400 gigabit, it became concerned about the size of the proposed pluggable modules, and the interface speeds needed between the switch silicon and the pluggable module.

“What jumped out at us is that we might be running into an issue here,” says Booth.

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Micro QSFP module to boost equipment port densities

Twelve companies are developing a compact Quad Small-Form-Factor Pluggable (QSFP) module. Dubbed the Micro QSFP (μQSFP), the multi-source agreement (MSA) will improve by a third the port count on a platform's face plate compared to the current QSFP.

Nathan Tracy

The μQSFP will support both copper and optical cabling, and will have an improved thermal performance, benefitting interfaces and platforms.

“There is always a quest for greater port density or aggregate bandwidth,” says Nathan Tracy, technologist at TE Connectivity and chair of the μQSFP MSA.

The challenge for the module makers is to provide denser form factors to increase overall system traffic. “As we go to higher densities, we are also increasing the thermal load,” says Tracy. “And so now it is a mechanical and a thermal [design] problem, and both need to be solved jointly.”

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Altera unveils its optical FPGA prototype

Altera has been showcasing a field-programmable gate array (FPGA) chip with optical interfaces. The 'optical FPGA' prototype makes use of parallel optical interfaces from Avago Technologies.

Combining the FPGA with optics extends the reach of the chip's transceivers to up to 100m. Such a device, once commercially available, will be used to connect high-speed electronics on a line card without requiring exotic printed circuit board (PCB) materials. An optical FPGA will also be used to link equipment such as Ethernet switches in the data centre.

"It is solving a problem the industry is going to face," says Craig Davis, product marketing manager at Altera. "As you go to faster bit-rate transceivers, the losses on the PCB become huge."

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