Reason Analysis of Using AOC Active Optical Cable in Data Center Wiring

40G/100G AOC active optical cable has been globally introduced throughout the data center field. Compared to 40G DAC copper cable, 40G AOC active optical cable has unparalleled advantages in data transmission environment above 7 meters, including the smaller size, lighter weight, easier bending, easier management, longer signal transmission distance, etc. In the data center, the same goals can be achieved with a 40G SR4 optical transceiver. The differences between 40G AOC active optical cable and SR4 optical transceiver are analyzed as follows:

1. Insertion loss analysis of 40G AOC active optical cable and SR4 optical transceiver

With the same transmission distance, for SR4 optical transceiver, different optical fiber jumpers that are connected to the same module will produce different insertion loss and return loss, which is basically a common problem. However, as long as the variation is within the range, there will be no significant change in the eye map and other related indexes.

The AOC active optical cable which is well made is basically stable and has better rocking performance. The repeated test of the SR4 optical transceiver produced a large fluctuation.

2. Four-quadrant test of 40G AOC active optical cable and SR4 optical transceiver

It is measured at four combinations of input voltage and signal amplitude to ensure that the performance can be maintained at both the lowest and highest voltages and temperatures. AOC active optical cable is required to pass quadrant tests with a wide temperature range to ensure that the MPO interface and cable of AOC will not melt at high temperatures. The performance change of MPO interface itself at high and low temperatures can meet the change of 0.3 dB, and the materials used are PEI materials that can resist the temperature of above 120 degrees.

As an all-in-one product, the all-in-one test ensures the performance of the product, which may be more stable than SR4 optical transceiver that adopts MPO jumper with uncertain performance. Compared with SR4 optical transceiver that confirms the quality through optical eye diagram, AOC active optical cable mainly uses the eye diagram to judge the quality of indicators.

3. DDM monitoring of 40G AOC active optical cable and SR4 optical transceiver

QSFP+ SR4 optical transceiver has the DDM monitoring function. When receiving coupling, the ADC value of the receiver can be monitored in real time to determine the optimal coupling. Therefore, SR4 is more superior than AOC in terms of receiving sensitivity.

4. Transmission distance of 40G AOC active optical cable and SR4 optical transceiver

There is not much difference in the OM3 fibers, but the 40G QSFP+ SR4 optical transceiver provides better performance control. QSFP+SR4 is recommended if you want to achieve a longer distance (> 300 m) transmission.

Active fiber optical cable (AOC) is recommended based on the data connection in the data center, because it provides better wiring consistency and repeatability, and the closed ends are easier to avoid the effects of environmental and vibration oscillations. If there is a failure, it can be replaced directly without the need to carry out a series of end-to-plug tests of 40G QSFP+SR4 optical transceiver and MPO jumper on site, which is more beneficial to save costs.