Pluggable Coherent DWDM 10Gig

Phil Bedard bedard.phil at
Fri Apr 25 22:12:50 UTC 2014

What are you trying to do?  Why do you need the receive side to be tuned
to a specific narrowband wavelength?  Coherent doesn't really make sense
in 10G becaue 10G long-haul is still on/off keyed and doesn't care about
phase. Coherent detectors are needed where phase of the signal is
important like long-haul 100G where multiple analog photonic signals are
mixed on the transmit side.  It also requires DSPs to process the received
information. You aren't going to put a DSP inside a SFP+ cage.  With
CFP2/CFP4/QSFP28 the optics vendors would like people to start building
the DSP onto line cards, whether it be a router or transport shelf,
because there just isn't the packaging room to make it happen.

Terastream today doesn't use integrated router optics, they use Cisco's
nV-Optical solution. The connection between the router and transport shelf
is still gray optics, but the system is managed as a single logical
entity, with a 1:1 correlation between router port and transponder.  You
"tune" the wavelength on the router because of the 1:1 correlation.
Terastream just uses passive DWDM muxes/demuxes, also part of the same
Cisco transport solution, and Cisco VOAs/amps.


On 4/25/14, 2:59 PM, "Tim Durack" <tdurack at> wrote:

>On Mon, Apr 21, 2014 at 2:42 PM, Tim Durack <tdurack at> wrote:
>> Anyone know if pluggable coherent DWDM 10Gig optics exist? (I'm finding
>> such thing.)
>> How about narrow-band/filtered receive 10Gig optics? (Inline FBG filter
>> receive side might be doable?)
>> --
>> Tim:>
>> p.s. Before you ask, DTAG Terastream has got me thinking...
>As a follow up, there are lots of people willing to sell various flavours
>of DWDM optics, but as I suspected, there is no such thing as a
>coherent/tuned/filtered receive 10GigE DWDM optic. All 10GigE optics are
>wide-band receive. However, you can get inline optical filters, Santec
>OFM-15 for example. Investigating...

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