2x 100G DWDM Coherent Solution for Up to 200km Point-to-Point Interconnect

Background

Challenges

At a long-haul distance of 200km, how to achieve point-to-point (P2P) direct interconnection without adding relay optical amplifiers (OA)?

Solutions

To break out the bottleneck, the QSFPTEK IT engineer designed a 100G DWDM coherent solution for long distance 100G network.

● First, to meet customers’ requirements on traffic channels of at least two and potentially more in the future, a paired 40CH passive DWDM Mux/Demux (Model: DMD40-1U01-C2160-31M) is deployed at each data center. The DWDM Mux/Demux integrates the DWDM multiplexer and demultiplexer in one block and supports up to 40× 100G traffic transmission over dual SMF.

● Second, this solution requires ultra-long-distance transmission of up to 200km, which is out of reach for regular 100G QSFP28 transceivers. Hence we use 2CH 100G Transponder (Model: QT860-OTDT2) to convert 2 channels of 100G QSFP28 optical signal into 2 channels of 100G CFP2 coherent DWDM optical signal, making legacy 100G optical signals become 100G DWDM traffic for long-distance transmission. 

● Third, considering loss along the link, EDFA amplifiers are deployed to compensate for power. At each side, a BA is used at the transmitter sides behind the DWDM MUX/DEMUX to boost the output optical power of the system and a PA is used at the receiver sides before the DWDM MUX/DEMUX of the system to improve the input optical power.

● In addition, we reuse the idle variable optical attenuators (VOA) and Raman-off amplifiers the customers already own. The VOA makes it simple and efficient to adjust the input and output power of the system, simplifying operation complexity and saving time. The Raman amplifier significantly improves the line transmission performance. As it owns a low noise figure, the nonlinear effect will not obviously increase.

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Customer Benefits

100G coherent signals do not require a dispersion compensation module (DCM) for long-distance transmission and can achieve ultra-long-distance P2P interconnect of 200km via G.652 optical fiber without adding relay OA sites or signal regeneration. It also reduces the customer's system construction, operation and maintenance costs.

In this case, QSFPTEK technical team helps the client build up a cost-effective and easy-to-manage 100G DWDM coherent solution using QT860 series products, assuring high-performance bandwidth and link security.