optical circulator as a bidirectional one fiber solution

Mon Aug 13 21:56:04 UTC 2018

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.

On Mon, Aug 13, 2018 at 1:57 PM Ben Cannon <ben at 6by7.net> wrote:

> Good news about almost all optics, their Rx window is pretty wide. Meaning
> a 1550nm optic will activate the receiver on a 1560nm optic just fine (and
> probably anything in the 1500nm band).  Careful use of specialized single
> strand DWDM muxes (FS.com) can yield great bidi-like results with
> increased channel count.
>
> -Ben
>
> On Aug 13, 2018, at 10:49 AM, Eric Kuhnke <eric.kuhnke at gmail.com> wrote:
>
> Something that is broadly the same as a coherent 100G QPSK single
> wavelength optical module, but in two different frequencies, and a passive
> CWDM mux/demux prism at each end might work. The limitation would be
> availability of optics for a modern 100G MSA that are both coherent and
> Tx/Rx at two different THz frequencies.
>
> Or with some box and vendor equipment in between, such as:
>
>
> http://cdn.extranet.coriant.com/resources/Application-Notes/AN_Groove_Bidirectional_Fiber_74C0169.pdf?mtime=20180206023321
>
> On Tue, Aug 7, 2018 at 1:00 PM Daniel Corbe <dcorbe at hammerfiber.com>
> wrote:
>
>> On 8/7/2018 15:46:03, "Baldur Norddahl" <baldur.norddahl at gmail.com>
>> wrote:
>>
>> >Hello
>> >
>> >There is a lack of bidirectional one fiber (BIDI) options for 40G and
>> >100G optics. Usually BIDI is implemented using two CWDM wavelengths,
>> >one for tx and one for rx. However there is also a lack of CWDM and
>> >DWDM options for 40G and 100G.
>> >
>> >Would it be possible to use an optical circulator like this one
>> >(customized to 1310 nm)?
>> >
>> >https://www.fs.com/de/en/products/33364.html
>> >
>> >Combined with a traditional two fiber 1310 nm 10 km 40G QSFP module
>> >like this: https://www.fs.com/de/en/products/24422.html
>> >
>> >The link distance would be 5 km.
>> >
>> >The optical circulator separates tx and rx by the direction the light
>> >travels in. It would work even though both directions use the same
>> >wavelength. There will likely be some reflection but hopefully
>> >attenuated enough that it is regarded as background noise.
>> >
>> >Has anyone done this? Any reason it would not work?
>> >
>> >Regards,
>> >
>> >Baldur
>> >
>>
>> The main issue you're going to run into (especially trying to plug
>> anything into a DWDM shelf) is 40G and 100G transceivers usually emit 4
>> lanes of traffic instead of a single lane like 10 and 1G optics do.
>>
>> I'd imagine that's why there are so few solutions that don't involve
>> things like OTN.
>>
>>
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