Data Center Why use AOC

The entire data center has begun global import 40G AOC, relative to 40G DAC copper, 40G AOC at 7 meters above data transmission environment with unparalleled advantages, including smaller, lighter, easier to bend and more easy management, signal transmission over longer distances and so on. AOC assemblies are full-duplex structure:
AOC system architecture diagram
AOC system architecture diagram
In the data center, if 40G SR4 optical modules can also obtain these goals.

Differences 40G AOC and SR4 module as follows:

1) Insert the return loss analysis: For the same distance, with the current technology and design, SR4 repeatability and interchangeability performance optical module interface inferior to 40G AOC. SR4 optical modules for different fiber jumpers plug the same module will have different insertion loss and return loss, this is basically a common problem. But insofar as the amount of change in line with the scope of the test and other related indicators of the eye will not be too significant change. And making good AOC this respect can be maintained basically stable, rocking performance better. SR4 repeatability test in the following table, showing the occurrence of a large volatility.
SR4 plug repeatability of test data
SR4 plug repeatability of test data

2) four-quadrant test: is the input voltage and signal amplitude measurements four combinations in order to ensure the lowest and highest voltage and temperature can maintain performance. AOC through a wide temperature range four quadrant tests to ensure the MPO connector and cable AOC will not melt at high temperatures. MPO interface itself changes in high and low temperature performance is to meet 0.3dB variation, materials used are also resistant to more than 120 degrees PEI material. As integrated molding products, integration tests to ensure product performance, this may appear to be more stable than using SR4 module optional uncertain performance of MPO jumpers. SR4 confirmed by mass relative to the optical eye diagram, AOC primarily by electric eye to judge the merits of indicators.

3) DDM monitor: SR4 have DDM monitoring function to see in real-time monitoring to determine the optimal size of the coupling receiving end ADC value when receiving coupling, so the reception sensitivity SR4 appear superior than some of the AOC. But SR4 optical modules and 40G AOC currently can not achieve real-time monitoring of optical power.

4) Transmission distance: not much difference between the two on OM3 fiber. But SR4 optical module can better control performance, if you want to achieve longer distances (> 300 m) of transport recommended SR4.

Summary: Based on the data within the data center connection, we recommend using active optical cable (AOC). The reason is that this AOC wiring consistency and repeatable, closed at both ends is easier to avoid environmental impact and vibration swing. If the failure can be directly replaced, without the need for on-site to do SR4 optical modules and MPO series termination jumper plug test cost savings.

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