The CWDM8 MSA avoids PAM-4 to fast-track 400G

Another multi-source agreement (MSA) group has been created to speed up the market introduction of 400-gigabit client-side optical interfaces.

The CWDM8 MSA is described by its founding members as a pragmatic approach to provide 400-gigabit modules in time for the emergence of next-generation switches next year. The CWDM8 MSA was announced at the ECOC show held in Gothenburg last week.

Robert BlumThe eight-wavelength coarse wavelength-division multiplexing (CWDM) MSA is being promoted as a low-cost alternative to the IEEE 803.3bs 400 Gigabit Ethernet Task Force’s 400-gigabit eight-wavelength specifications, and less risky than the newly launched 100G Lambda MSA specifications based on four 100-gigabit wavelengths for 400 gigabit.

“The 100G Lambda has merits and we are also part of that MSA,” says Robert Blum, director of strategic marketing and business development at Intel’s silicon photonics product division. “We just feel the time to get to 100-gigabit-per-lambda is really when you get to 800 Gigabit Ethernet.”

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MultiPhy unveils 100G single-wavelength PAM-4 chip

A chip to enable 100-gigabit single-wavelength client-side optical modules has been unveiled by MultiPhy. The 100-gigabit 4-level pulse amplitude modulation (PAM-4) circuit will also be a key building block for 400 Gigabit Ethernet interfaces that use four wavelengths.

Source: MultiPhy

Dubbed the MPF3101, the 100-gigabit physical layer (PHY) chip is aimed at such applications as connecting switches within data centres and for 5G cloud radio access network (CRAN).

“The chip has already been sent out to customers and we are heading towards market introductions,” says Avi Shabtai, CEO of MultiPhy.

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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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New MSA to enable four-lambda 400-gigabit modules

A new 100-gigabit single-wavelength multi-source agreement (MSA) has been created to provide the industry with 2km and 10km 100-gigabit and 400-gigabit four-wavelength interfaces.

Mark NowellThe MSA is backed by 22 founding companies including Microsoft, Alibaba and Cisco Systems.

The initiative started work two months ago and a draft specification is expected before the year end.

“Twenty-two companies is a very large MSA at this stage, which shows the strong interest in this technology,” says Mark Nowell, distinguished engineer, data centre switching at Cisco Systems and co-chair of the 100G Lambda MSA. “It is clear this is going to be the workhorse technology for the industry for quite a while.”

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Inphi unveils a second 400G PAM-4 IC family

Inphi has announced the Vega family of 4-level, pulse-amplitude modulation (PAM-4) chips for 400-gigabit interfaces.

The 16nm CMOS Vega IC family is designed for enterprise line cards and is Inphi’s second family of 400-gigabit chips that support eight lanes of 50-gigabit PAM-4.

Its first 8x50-gigabit family, dubbed Polaris, is used within 400-gigabit optical modules and was announced at the OFC show held in Los Angeles in March.

“Polaris is a stripped-down low-power DSP targeted at optical module applications,” says Siddharth Sheth, senior vice president, networking interconnect at Inphi (pictured). “Vega, also eight by 50-gigabits, is aimed at enterprise OEMs for their line-card retimer and gearbox applications.”  

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