The OIF's coherent optics work gets a ZR+ rating

The OIF has started work on a 1600ZR+ standard to enable the sending of 1.6 terabits of data across hundreds of kilometres of optical fibre. 

The initiative follows the OIF's announcement last September that it had kicked off 1600ZR. ZR refers to an extended reach standard, sending 1.6 terabits over an 80-120km point-to-point link. 

1600ZR follows the OIF's previous work standardising the 400-gigabit 400ZR and the 800-gigabit 800ZR coherent pluggable optics.      

The decision to address a 'ZR+' standard is a first for the OIF. Until now, only the OpenZR+ Multi-Source Agreement (MSA) and the OpenROADM MSA developed interoperable ZR+ optics.

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Optical networking's future

Shown is Professor Polina Bayvel in her lab at University College London. Bayvel gave the opening plenary talk at ECOC.

Should the industry do more to support universities undertaking optical networking research? Professor Polina Bayvel thinks so and addressed the issue in her plenary talk at the ECOC conference and exhibition held in Glasgow, Scotland, earlier this month.

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How DSP smarts continue to improve optical transport

• Kim Roberts explains the signal processing techniques Ciena is using for its WaveLogic 6 coherent DSP.
• Roberts explains how the techniques squeeze, on average, a 15 per cent improvement in spectral efficiency.
• The WaveLogic 6 Extreme chip can execute 1,600 trillion (1.6 x 10¹⁵) operations per second and uses the equivalent of 4km of on-chip copper interconnect.

Part 2: WaveLogic 6's digital signal processing toolkit

Kim Roberts, Ciena’s vice president of WaveLogic Science and winner of the 2019 John Tyndall Award

Bumping into Kim Roberts on the way to the conference centre at OFC, held in San Diego in March, I told him how, on the Ciena briefing about its latest WaveLogic 6 coherent digital signal processor (DSP), there had been insufficient time to dive deeply into the signal processing techniques used.

“What are you doing now?” said Roberts.

“I’m off to the plenary session to catch the keynotes.”

Chatting some more, I realised I was turning down a golden opportunity to sit down with a leading DSP and coherent modem architect.

“Is that offer still open?” I asked.

He nodded.

We grabbed a table at a nearby cafe and started what would prove to be an hour-long conversation.

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Do optical DACs have a role in future coherent modems?

• A proposed optical digital-to-analogue converter (oDAC) concept offers several system benefits, including better signal performance, higher bit rates and lower power consumption.
• The oDAC design benefits coherent optics but can also be used in direct-detect designs. This article focusses on coherent optics.
• Coherent system vendors are aware of oDAC technology but it is not part of their current roadmaps. 

A 256-QAM constellation using a conventional coherent transmitter (left) and using the oDAC. Note there is no modulator loss (the full area is used) nor any optical warping using the oDAC. Source: Tomkos and Nazarathy.

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Nokia jumps a class with its PSE-6s coherent modem

• The 130 gigabaud (GBd) PSE-6s coherent modem is Nokia's first in-house design for high-end optical transport systems 
• The PSE-6s can send an 800 gigabit Ethernet (800GbE) payload over 2,000km and 1.2 terabits of data over 100km.
• Two PSE-6s DSPs can send three 800GbE signals over two 1.2-terabit wavelengths

Nokia has unveiled its latest coherent modem, the super coherent Photonic Service Engine 6s (PSE-6s) that will power its optical transport platforms in the coming years.

The PSE-6s comes three years after Nokia announced its current generation of coherent digital signal processors (DSPs): the PSE-Vs DSP for the long-haul and the compact PSE-Vc for the coherent pluggable market.

Nokia is only detailing the PSE-6s; its next-generation coherent modem for pluggables will be a future announcement.

Nokia will demonstrate the PSE-6s at the upcoming OFC show in March while field trials involving systems using the PSE-6s will start in the year's second half. 

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Effect Photonics buys the coherent DSP team of Viasat

Effect Photonics has completed the acquisition of Viasat’s staff specialising in coherent digital signal processing and forward error correction (FEC) technologies and the associated intellectual property.

Harald Graber

The company also announced a deal with Jabil Photonics - a business unit of manufacturing services firm Jabil - to co-develop coherent optical modules that the two companies will sell.

The deals enable Effect Photonics to combine Viasat’s coherent IP with its indium phosphide laser and photonic integrated circuit (PIC) expertise to build coherent optical designs and bring them to market.

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Huawei sets transmission record with new modulator

Coherent discourse: Part 1

A paper from Huawei and Sun Yat-Sen University in the January issue of the Optica journal describes a thin-film lithium niobate modulator. The modulator enabled a world-record coherent optical transmission, sending nearly 2 terabits of data over a single wavelength.

Maxim Kuschnerov

Much of the industry’s focus in recent years has been to fit coherent optical technology within a pluggable module.

Such pluggables allow 400-gigabit coherent interfaces to be added to IP routers and switches, serving the needs of the data centre operators and telecom operators.

But research labs of the leading optical transport vendors continue to advance high-end coherent systems beyond 800-gigabit-per-wavelength transmissions.

Optical transport systems from Ciena, Infinera and Huawei can send 800-gigabit wavelengths using a symbol rate of 96-100 gigabaud (GBd).

Acacia Communications, part of Cisco, detailed late last year the first 1.2-terabit single-wavelength coherent pluggable transceiver that will operate at 140GBd, twice the symbol rate of 400-gigabit modules such as 400ZR. 

Now Huawei has demonstrated in the lab a thin-film lithium niobate modulator that supports a symbol rate of 220GBd and beyond.

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