At present, the global network traffic is rising, and users need more bandwidth to meet the application requirements, which promotes the wide application of 400G Ethernet in large data centers. As the key hardware equipment of optical network interconnection in data center, 400G optical module also has a good development prospect. More and more network communication equipment manufacturers, cloud service providers and optical device suppliers have joined the 400G army. In order to keep up with the trend of the times, ETU link has also entered the research and development stage of 400G products. In the next few years, a large number of 400G products will appear in the market to meet different network requirements, such as 400G QSFP-DD optical module, 400G QSFP-DD DAC direct attach cable, 400G QSFP-DD AOC active optical cable, etc.

The promulgation of the 200G/400G Ethernet standard has brought new optical module packages to the industry, such as QSFP-DD, OSFP and CFP8 defined by the IEEE and MSA groups. The optical interfaces of these packages use 16*25Gb/s NRZ or 8* 53Gb/s PAM4.

Although the use of PAM4 modulation technology can indeed greatly improve throughput, it also brings some problems to 400G, such as the physical structure becomes more complicated, and signal transmission is prone to errors. Therefore, complex 400G test projects have brought many new challenges to optical module suppliers. In order to ensure that the optical modules received by users are of good quality, optical module manufacturers must adopt more professional optical module testing equipment, and need to have a higher detection level and R&D technology. At the same time, it can ensure that 400G optical modules are compatible with existing ones. Network infrastructure equipment connection upgrade. In addition to the factors affecting the testing technology, the R&D/manufacturing/testing costs of 400G optical modules are also issues that manufacturers need to solve.

Although the 400G Ethernet standard has been approved for a long time, the entire industry (including OEMs, network operators, etc.) is still solving basic connection problems, such as trying to solve the problems of optical module transmission frame errors, data packet loss, etc., to ensure that the optical module Accuracy and reliability of transmission. For optical module manufacturers, product quality inspection is an important part of building customer trust.

The main test items of 400G optical modules include: extinction ratio and optical modulation amplitude test, forwarding performance test, eye pattern test, jitter test, bit error rate test, etc. However, although the complex 400G optical module testing technology has yet to be perfected, 400G Ethernet will flourish under the impetus of 5G, artificial intelligence, virtual reality (VR), cloud computing and other applications. At present, some manufacturers have begun to provide 400G solutions to the market, such as Cisco, Arista, etc. In the face of this situation, some smaller optical module suppliers regard 400G optical module testing as an important factor in their choice, because the quality and supply speed of 400G products determine their profitability.