The same objective can be got if uses 40G SR4 optical module in data center.

1. Analysis on insertion and return loss: for the same transmission distance, the repeatability and interchangeability of 40G AOC is better than SR4 optical module interface based on the current techniques and design. For SR4 optical module, insert the same module into different fiber cable or jumper, the insertion and return loss will be different. However, there is no obvious change of eye diagram and other related indicators as long as within the scope of compliance, and well-produced AOC is basically able to maintain stability in this aspect, the swing performance is also better. The following figure is the repeatability test of SR4 that shows the greater volatility.

2. Four-quadrant test: measure the 4 kinds of combinations of input voltage and signal amplitude to ensure that can maintain performance under the environment of lowest and highest voltage and temperature. AOC need to pass the four-quadrant test of wide temperature range to guarantee that MPO interface of AOC and optical cable will not melt at high temperatures. Generally the changes of MPO interface itself can meet the 0.3dB in high and low temperature performance, the material used is PEI which capable of more than 120 degrees. As an integrated molding product, the integrated test ensures product performance, which may be more reliable than adopts SR4 to select MPO jumper that has uncertain performance. Compared with SR4 which uses optical eye diagram to confirm quality, AOC mainly uses electrical eye diagram to judge the performance of indicators.

3. DDM monitoring: the function of DDM monitoring of SR4 that to real-time monitor the ADC value at the end of receiver when receiving and coupling, so that to determine the best coupling, so SR4 has a better performance on receiving sensitivity than AOC. However, now SR4 optical module and 40G AOC are still unable to achieve real-time optical power monitoring. 

4. Transmission distance: there is no obvious difference between SR4 and 40G AOC in OM3 fiber cable. But SR4 optical module could better control of performance, we suggest that adopts SR4 if need to achieve long-distance (>300 meters) transmission.

The data connection based on the internal data center suggested that adopts active optical cable because of AOC has a better performance on cabling consistency and repeatability, closed ends are easier to avoid the effects of the environment and vibration swing. It can be directly replaced if a failure occurs instead of doing a series of pluggable test for SR4 optical module and MPO jumper, so that the cost can be saved.