400ZR will signal coherent’s entry into the datacom world

• 400ZR will have a reach of 80km and a target power consumption of 15W 
• The coherent interface will be available as a pluggable module that will link data-centre switches across sites    
• Huawei expects first modules to be available in the first half of 2020
• At OFC, Huawei announced its own 250km 400-gigabit single-wavelength coherent solution that is already being shipped to customers

Coherent optics will finally cross over into datacom with the advent of the 400ZR interface.  So claims Maxim Kuschnerov, senior R&D manager at Huawei.

Maxim Kuschnerov400ZR is an interoperable 400-gigabit single-wavelength coherent interface being developed by the Optical Internetworking Forum (OIF) {add link}.

The 400ZR will be available as a pluggable module and as on-board optics using the COBO specification {add link}. The IEEE is also considering a proposal to adopt the 400ZR specification, initially for the data-centre interconnect market. “Once coherent moves from the OIF to the IEEE, its impact in the marketplace will be multiplied,” says Kuschnerov. 

But developing a 400ZR pluggable represents a significant challenge for the industry. “Such interoperable coherent 16-QAM modules won’t happen easily,” says Kuschnerov. “Just look at the efforts of the industry to have PAM-4 interoperability, it is a tremendous step up from on-off keying.” 

Despite the challenges, 400ZR products are expected by the first half of 2020.

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Lumentum jolts the industry with Oclaro acquisition

Lumentum announced on Monday its plan to acquire Oclaro in a deal worth $1.8 billion.

The prospect of consolidation among optical component players has long been mooted yet the announcement provided the first big news jolt at the OFC show, being held in San Diego this week. 

Alan Lowe“Combined, we will be an industry leader in telecom transmission and transport as well as 3D sensing,” said Alan Lowe, president and CEO of Lumentum, on an analyst call discussing the deal.

Lumentum says their joint revenues totalled $1.7 billion with a 39% gross margin over the last year. And $60 million in synergies are forecast in the second year after the deal closes, which is expected to happen later this year. 

The $1.8 billion acquisition will comprise 56 percent cash and 44 percent Lumentum stock. Lumentum will also raise $550 million to help finance the deal.

“This is a big deal as it consolidates the telecom part of the component market,” says Daryl Inniss, business development manager at OFS Fitel and former market research analyst.

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Coherent gets a boost with probabilistic shaping

Nokia has detailed its next-generation PSE-3 digital signal processor (DSP) family for coherent optical transmission.

The PSE-3s is the industry’s first announced coherent DSP that supports probabilistic constellation shaping, claims Nokia.

Probabilistic shaping is the latest in a series of techniques adopted to improve coherent optical transmission performance. These techniques include higher-order modulation, soft-decision forward error correction (SD-FEC), multi-dimensional coding, Nyquist filtering and higher baud rates.

Kyle Hollasch

“There is an element here that the last big gains have now been had,” says Kyle Hollasch, director of product marketing for optical networks at Nokia.

Probabilistic shaping is a signal-processing technique that squeezes the last bit of capacity out of a fibre’s spectrum, approaching what is known as the non-linear Shannon Limit.

“We are not saying we absolutely hit the Shannon Limit but we are extremely close: tenths of a decibel whereas most modern systems are a couple of decibels away from the theoretical maximum,” says Hollasch.

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Acacia announces a 1.2 terabit coherent module

Acacia Communications has given first details of its AC1200 coherent optical module, capable of transmitting up to 1.2 terabits of data. The custom coherent transceiver is being aimed at applications ranging from linking data centres to long-haul and even sub-sea transmissions and was announced at the recent ECOC show held in Gothenburg.

Channel capacity and link margin can be maximised by using the fractional QAM scheme. Source: Acacia.

The company is facing increasing market competition. Ciena has teamed up with Lumentum, NeoPhotonics, and Oclaro, sharing its high-end coherent DSP expertise with the three optical module makers. Meanwhile, Inphi has started sampling its 16nm CMOS M200, a 100- and 200-gigabit coherent DSP suitable for CFP2-ACO, CFP-DCO, and CFP2-DCO module designs.

The AC1200 is Acacia’s response, extending its high-end module offering beyond a terabit to compete with the in-house system vendors and preserve its performance lead against the optical module makers.

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Has coherent optical transmission run its course?

Feature: Coherent's future

Three optical systems vendors share their thoughts about coherent technology and the scope for further improvement as they look two generations ahead to symbol rates approaching 100 gigabaud   

Optical transmission using coherent detection has made huge strides in the last decade. The latest coherent technology with transmitter-based digital signal processing delivers 25x the capacity-reach of 10-gigabit wavelengths using direct-detection, according to Infinera.

Since early 2016, the optical systems vendors Infinera, Ciena and Nokia have all announced new coherent digital signal processor (DSP) designs. Each new generation of coherent DSP improves the capacity that can be transmitted over an optical link. But given the effectiveness of the latest coherent systems, has most of the benefits already been achieved?

Source: Infinera

“It is getting harder and harder,” admits Kim Roberts, vice president, WaveLogic science at Ciena. “Unlike 10 years ago, there are no factors of 10 available for improvement.”

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The OIF’s 400ZR coherent interface starts to take shape

Part 2: Coherent developments

The Optical Internetworking Forum’s (OIF) group tasked with developing two styles of 400-gigabit coherent interface is now concentrating its efforts on one of the two.

When first announced last November, the 400ZR project planned to define a dense wavelength-division multiplexing (DWDM) 400-gigabit interface and a single wavelength one. Now the work is concentrating on the DWDM interface, with the single-channel interface deemed secondary. 

Karl Gass"It [the single channel] appears to be a very small percentage of what the fielded units would be,” says Karl Gass of Qorvo and the OIF Physical and Link Layer working group vice chair, optical, the group responsible for the 400ZR work.

The likelihood is that the resulting optical module will serve both applications. “Realistically, probably both [interfaces] will use a tunable laser because the goal is to have the same hardware,” says Gass.   

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DIMENSION tackles silicon photonics’ laser shortfall

Ambitious European project seeks to combine lasers, electronics and photonics, all on one chip

Several companies and research institutes, part of a European project, are developing a silicon photonics process that combines on-chip electronics and lasers. Dubbed Dimension (Directly Modulated Lasers on Silicon), the silicon photonics project is part of the European Commission’s Horizon 2020 research and innovation programme.

 The Dimension process showing the passive photonics, dielectric material, BiCMOS circuitry, and the on-chip lasers and modulators. The indium phosphide material is shown in red. Source: Dimension.

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