Download Coherent Alien Waves over a DCM-compensated DWDM

Coherent Alien Waves over a DCM-compensated DWDM network
Performance measurements of 100Gb/s Coherent Alien Waves over a Dispersion
Compensating Module-compensated optical transmission infrastructure
P.Bolletta, M.Carboni, G.Vuagnin
Consortium GARR
The Italian Research and Education Network
The optical network operated by GARR is based on two infrastructures that are separate, and employ
different technologies. GARR-X, deployed in Central and Northern Italy since 2011, is optimized for
Intensity Modulation with Direct Detection (IM-DD), 10Gb/s channels, where DCMs (Dispersion
Compensating Modules) are used to compensate for chromatic dispersion. In Southern Italy, in the
network called “GARR-X Progress”, a more innovative technology has been deployed operationally
since the beginning of 2015. This GARR-X Progress infrastructure is DCM-free and is used for the
transmission of coherent optical super-channels at 500Gb/s.
The existence of these two different chromatic dispersion compensation techniques, and, for the near
future, the need to potentially support only a small number of 100Gb/s client services on the original
GARR-X infrastructure has led to plan a study of the performance, and possible limitations, of
deploying coherent “alien” wavelengths over a DCM-based network.
Our aim is to test the coexistence of native 10Gb/s IM-DD optical channels and coherent alien
wavelengths of higher bit rate on the GARR-X infrastructure. This is equipped with Huawei OptiX
platform that includes ROADM nodes, add/drop modules able to support up to 80 channels (with 50GHz
spacing) in the C-band, OTN switching matrices, amplification sites with EDFA or Raman amplifiers,
and DCM modules for the chromatic dispersion correction.
For the 100Gb/s coherent signals we will use the same equipment deployed in GARR-X Progress, which
is the Infinera DTN-X. This platform is able to transmit 500Gb/s super-channels, based on optical
carriers which can be enabled and managed individually with QPSK and/or BPSK modulation, allowing
a flexible use of the available spectrum, and an optimal balance between reach and capacity.
The study is designed to test the performances of native IM-DD channels and alien coherent
wavelengths which are transported simultaneously on the DCM-based infrastructure. We will test a
range of scenarios that differ in the use of guard bands between channels of different technology, and for
different coherent modulation schemes. The final goal is to determine if a smooth migration of the
optical network in GARR-X towards the coherent model implemented in GARR-X Progress is feasible.