What about 100Ghz ITU spacing on the tx, are the rx optics broad enough to take the off-band input?
-Ben > On Aug 13, 2018, at 3:19 PM, Jameson, Daniel <[email protected]> > wrote: > > You would still need to frequency shift TX and RX. They are travelling > opposite directions on the same piece of glass; as the traffic rate > increases the likelihood of collisions increases and you’ll start to get > errors. The collision would either cancel the ‘bit’ or act like OBI and get > erroneous bits and checksum errors or missing chunks from the constellation. > There are BIDI 100G transceivers for Multi-mode available today based on the > Foxconn optics, I’d imagine we’ll see BIDI for the O and C bands in the next > 18 months. > > From: NANOG [mailto:[email protected]] On Behalf Of Eric Kuhnke > Sent: Monday, August 13, 2018 3:56 PM > To: [email protected]; [email protected] list > Subject: Re: optical circulator as a bidirectional one fiber solution > > 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 <[email protected]> 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 <[email protected]> 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 <[email protected]> wrote: > On 8/7/2018 15:46:03, "Baldur Norddahl" <[email protected]> > 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.
