Ciena sends a 1.6T optical lambda over a 470km link

• Ciena details its first live trial result using its latest WaveLogic 6 Extreme coherent modem.
• The modem will be generally available at the end of the month.  

Ciena has detailed its newest coherent modem's first optical networking performance: sending 1.6 terabits of data over a 470km fibre link.   

Helen Xenos

The field trial used Ciena's WaveLogic 6 Extreme coherent modem in telecom operator Arelion's live network.

The link connects an Equinix data centre in Ashburn to a Telxius submarine cable landing station also in Virginia. 

"The fact that we are achieving 1.6-terabit wavelengths across close to 500 kilometres is a testament to the performance and integrity of the design," says Helen Xenos, senior director of portfolio marketing at Ciena.

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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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