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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Ciena advances coherent technology on multiple fronts

• Ciena has unveiled the industry’s first coherent digital signal processor (DSP) to support 1.6-terabit wavelengths
• Ciena announced two WaveLogic 6 coherent DSPs: Extreme and Nano
• WaveLogic 6 Extreme operates at a symbol rate of up to 200 gigabaud (GBd) while the Nano, aimed at coherent pluggables, has a baud rate from 118-140GBd

Part 1: WaveLogic 6 coherent DSPs

Helen Xenos

Ciena has leapfrogged the competition by announcing the industry’s first coherent DSP operating at up to 200GBd.

The WaveLogic 6 chips are the first announced coherent DSPs implemented using a 3nm CMOS process.

Ciena’s competitors are - or will soon be - shipping 5nm CMOS coherent DSPs. In contrast, Ciena has chosen to skip 5nm and will ship WaveLogic 6 Extreme coherent modems in the first half of 2024.

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Nubis' bandwidth-packed tiny optical engine

• Nubis Communications has revealed its ambitions to be an optical input-output (I/O) solutions provider
• Its tiny 1.6-terabit optical engine measures 5mm x 7.5mm
• The optical engine has a power consumption of below 4 picojoule/bit (pJ/b) and a bandwidth density of 0.5 terabits per millimetre.
• “Future systems will be I/O with an ASIC dangling off it.”

Nubis Communications has ended its period of secrecy to unveil an optical engine targeted at systems with demanding data input-output requirements.

Dan HardingThe start-up claims its optical engine delivers unmatched bandwidth density measured in terabits per millimetre (T/mm) and power consumption performance metrics.

“In the timeframe of founding the company [in 2020], it became obvious that the solution space [for our product] was machine learning-artificial intelligence,” says Dan Harding, the CEO of Nubis.

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Teramount brings pluggability to co-packaged optics

Hesham Taha, the CEO and co-founder of Teramount, describes the last two years for his company as eventful.

"Many things have happened on many fronts," he says.

Teramount has developed a fibre assembly technology for designs integrating photonics and chips.

Hesham Taha

The start-up has raised $20 million in funding and has 30 staff. In addition, the company is recruiting staff experienced in manufacturing processes.

"The funding helps to support what we are working on today, which is manufacturing readiness," says Taha.

Taha also notes marketplace changes as when the rising interest in co-packaged caused some companies that had stepped out of silicon photonics to return.

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OFC 2023 show preview

• Sunday, March 5 marks the start of the Optical Fiber Communication (OFC) conference in San Diego, California
• The three General Chairs - Ramon Casellas, Chris Cole, and Ming-Jun Li - discuss the upcoming conference

OFC 2023 will be a show of multiple themes. That, at least, is the view of the team overseeing and coordinating this year's conference and exhibition.

General Chair Ming-Jun Li of Corning who is also the recipient of the 2023 John Tyndall Award (see profiles, bottom), begins by highlighting the 1,000 paper submissions, suggesting that OFC has returned to pre-pandemic levels.

Ramon Casellas, another General Chair, highlights this year's emphasis on the social aspects of technology. "We are trying not to forget what we are doing and why we are doing it," he says.

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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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How to shepherd a company’s technologies for growth

CTO interviews part 3: Dr Julie Eng

• Eng is four months into her new role as CTO of Coherent.
• Previously, she headed Finisar’s transceiver business and then the 3D sensing business, first at Finisar and then at II-VI. II-VI changed its name to Coherent in September 2022
• “CTO is one of these roles that has no universal definition,” says Eng

Dr Julie Eng

Julie Eng loved her previous role.

She had been heading II-VI’s (now Coherent’s) 3D sensing unit after being VP of engineering at Finisar’s transceiver business. II-VI bought Finisar in 2019.

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