Graphene Sheath Modulates Fiber-Optic Transmission At 200 GHz

An anonymous reader writes "Researchers in China have shown that a graphene sheath can modulate light transmission through an optical fiber at 200 GHz. The graphene, even crudely draped over the optic fiber on a microscope slide, absorbed some of the light passing through the fiber. But a preceding short-wavelength light pulse could temporarily disable the effect, enabling an all-optical infrared fiber-optic switch. Recovery was fast enough to enable modulation of transmitted light at 200 GHz using conventional fiber-optic communication wavelengths and thinned commercial telecommunications fibers. The findings could have use in telecommunications industry and future high-speed on-chip optical interconnects."

Comments

And on the far end?

[Shatrat]

It sounds like this is just very high speed On Off Keying, which is not only limited by modulation but also by the ability to clearly receive that signal on the far end.
This could be an alternative to coherent phase shift keying as a short range 100G+ interconnect though, where dispersion and noise aren't an issue.

Re:And on the far end?

[kaiser423]

It's modulation depth (per the abstract) is only 38%, so it's not quite a broad-band as on-off-keying. More like a non-optimal AM modulation. Still, if you can do it at those speeds that's head and shoulders above and beyond what we have now.

Another key benefit would be the simplification of encoding/decoding hardware. Using coherent PSK, QAM and other schemes there's quite a bit of effort put into determining the channel, etc to be able to know your current place in the constellation which can be a problem in the presence of noise sources. There's the well-known algorithms, tons of proprietary ones and new research papers every day on ways to betermine estimate the transmission channel to allow for more points (bits) in a constellation. Some of the QAM's, after disruption take over 100,000 symbols to re-lock to the bit stream. But that's the price you pay to shove more data down the pipe. If this works well though, you can get rid of all of that logic, stringent requirements on the transmission media and improve immunity to noise because with a simple AM, it only takes one symbol to re-lock onto the bit stream. They're dead simple to implement and robust as can be.

I can definitely see some really big uses for this if all goes well.