optical circulator as a bidirectional one fiber solution

Jared Mauch jared at puck.nether.net
Mon Aug 13 22:43:56 UTC 2018

> On Aug 13, 2018, at 5:56 PM, Eric Kuhnke <eric.kuhnke at gmail.com> wrote:
> For 1 and 10Gbps OOK modulation yes, but not for something like a ITU DWDM grid channelized or tunable coherent optic. In which the (QPSK, 8PSK, 16QAM) signal has a specific THz width and frequency not unlike a radio operating in a very, very narrow waveguide.

There are some DCO 100G coherent optics on the market, but I think this thread is more about why there’s not much in the way of 40/100g transmission speed, but it really is about how 10G was one of the last walls where OOK was a thing.  Once you went 40G/100G you went to parallel signals, either in CDWDM form or parallel signals on parallel fibers (eg: those MPT/MPO cables we all get to enjoy).

If you talk to the optics folks you can get customized tx/rx optics, and in theory you could get an optimized 100G-LR4 or 100G-ER4-Lite optic, but even those the reach is quite limited to around 25Km while in the 10G space you can get up to 80-120km with a filter and a bunch of pluggable fixed channel (or tunable) optics.

You can get decent 100G OEO solutions for a fair price per channel but you’re still looking at $$ compared to just building a 40x10G system due to the cost differences.

Without more details like your link budget, etc.. it’s hard to suggest options other than get at least 2 fibers :-)

I know some vendors are working on some creative 1 fiber solutions due to the way the dark fiber is taxed in Europe, so you should be talking to the usual suspects..

- Jared

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