[rassibassi]

Not practical yet, the novelty is the frequency comb which allows +200 channels across wavelength with only a single laser, where before one required 200 lasers.

In an experiment like this, only the initial light source is modulated and therefore all channels carry the same data. The equipment for the transmitter and receiver chain is so expensive that university labs can barely afford one of each.

[cycomanic]

Almost correct. You typically need 2-4 transmitters to emulate the system. So you modulate one or two channels under test and modulate the rest of the band with a single modulator and use some decorrelation tricks to be realistic. Then you scan your channels under test through the whole band. This is in typically a lower bound of performance, i.e. a real system would likely perform better. As you said, using individual transmitters is economically unfeasible even for the best equipped industry labs.

[Dylan16807]

Does that mean "We experimentally demonstrate transmission of 1.84 Pbit s–1" in the paper abstract is a lie?

[henrikeh]

I worked on this project and cycomanic summarizes the practice well. I’ve written more on it here: https://news.ycombinator.com/item?id=33321506

[Dylan16807]

Well, the technology is just as impressive either way, but I think "we experimentally demonstrate transmission of 1.84 Pbit s–1" is misleading. The capacity was demonstrated piecewise but that data rate was not demonstrated.