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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Fujitsu Labs adds processing to boost optical reach

Fujitsu Labs has developed a compensation technique that tackles non-linear effects in a coherent receiver-based optical transmission system. The technique promises to boost the reach of 100 Gigabit-per-second (Gbps) and future higher speed systems.

“That is one of the virtues of the technology; it is not dependent on the modulation format or the bit rate”

Takeshi Hoshida, Fujitsu Labs

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