Existing and emerging network technologies are driving the need for high-density optical connectivity solutions to address the trends to optimized cable management and data center real estate usage. In order to satisfy the demands of higher bandwidth and more applications in a variety of cloud computing environments, active optical cable (AOC) has emerged. This article will introduce a very popular type of AOC —40G QSFP+ AOC in data center applications.
40G AOC, is a type of active optical cable for 40GbE applications that is terminated with 40GBASE-QSFP+ on one end, while on the other end, in addition to QSFP+ connector, it can be terminated with SFP+ connector, LC, SC, FC, and ST connector etc. The 40G QSFP+ AOC is a parallel 40Gbps quad small form factor pluggable (QSFP+) active optical cable, which supplies higher port density and total system cost. The QSFP+ optical modules provide four full-duplex independent transmit and receive channels, each are able of 10Gbps operation 40Gbps aggregate bandwidth of at least 100m multimode fiber. Most DAC assemblies have one module on each end of the cable. But there is a special kind of DAC assembly which may have 3 or 4 modules on one end of the cable. For instance, Cisco QSFP-4X10G-AOC5M compatible QSFP+ to 4SFP+ breakout AOC from Fiberstore has a single QSFP+ module rated for 40-Gbps on one end and four SFP+ modules, each rated for 10-Gbps, on the other end.
Active Optical Cable (AOC) is used for short-range multi-lane data communication and interconnect applications. It uses electrical-to-optical conversion on the cable ends to improve speed and distance performance of the cable without sacrificing compatibility with standard electrical interfaces. The 40G QSFP+ AOC is a high performance, low power consumption integrated cable for short-range multi-lane data communication and interconnect applications, supporting 40G Ethernet, fiber channel and PCIE. It is compliant with the QSFP MSA and IEEE P802.3ba 40GBASE-SR4. It integrates four data lanes in each direction with 40 Gb/s aggregate bandwidth. Each lane is capable of transmitting data at rates up to 10Gb/s with lengths ranging from one to 100 m. With its benefits, 40G QSFP+ AOC is widely used in many fields as well as promoting the traditional data center to step into optical interconnection.
- Cost: 40G AOCs cost lower than SR4 modules and do not need to use with extra fiber patch cables. For instance, HP 720205-B21 compatible QSFP+ to QSFP+ active optical cables are suitable for very short distances and offer a very cost-effective way to establish a 40-gigabit link between QSFP ports of HP switches within racks and across adjacent racks. Besides, when using 40G AOC, there are no cleanliness issues in optical connector and there is no need to do termination plug and test when troubleshooting, which can help user save more time and money.
- Insertion Loss & Return Loss: Under the same case of transmission distance, the repeatability and interchangeability performances of SR4 module interface are not good as 40G AOC. What’s more, when different fiber optic patch cables plug into the module, it will have the different insertion loss and return loss. Even for the same module, this issue is existed. Of course, the related metrics such as the testing eye pattern will have no significant changes so long as the variation in and conformed to the scope. In contrast, an AOC with good performance is more stable and has better swing performance than SR4 modules in this situation.
Fiberstore’s AOCs achieve high data rates over long reaches which are the best solutions for high-performance computing and storage applications. We supply AOC products such as 10G SFP+ AOCs, 40G QSFP+ AOCs, QSFP+ to 4 SFP+ AOCs, QSFP+ to 8 x LC AOCs and 120G CXP AOCs etc. In addition, custom cables are also available in various lengths. Recently, Fiberstore has cut the price of its direct attach cable (DAC) products in order to offer a more cost-effective high speed transmission solution for the old and new customers.