Optical module type

Several common types of optical modules and several important factors that should be paid attention to when purchasing optical modules, hope to be helpful to everyone.

Common Optical Module Types

Before discussing how to choose an optical module, it is necessary for us to have a basic understanding of common packaged optical modules. This part will introduce the optical modules in SFP, SFP+, QSFP+ and QSFP28 packages respectively. As for the optical modules in GBIC, XFP and CFP packages, they will not be described in detail here.

SFP optical module

The SFP optical module is a mini version of the GBIC optical module. The functions of the two are roughly the same, but the size of the SFP optical module is much smaller than that of the GBIC optical module. It is generally used in SONET/SDH networks, 100M/Gigabit Ethernet and other high-speed transmission applications.

10G SFP+ optical module

The 10G SFP+ optical module is an upgraded version of the SFP optical module. The physical package of the two is the same, but the SFP+ optical module can support a transmission rate of 10Gbps. Compared with other 10G optical modules (such as Xenpak and XFP optical modules), the SFP+ optical module has the smallest volume and is most suitable for high-density port applications. Now it has become the most popular 10G optical module.

40G QSFP/QSFP+ optical module

The 40G QSFP/QSFP+ optical module complies with Ethernet, Fiber Channel, InfiniBand and SONET/SDH standards. The 40G QSFP optical module uses four 4Gbit/s transmission channels to transmit data, and the 40G QSFP+ optical module uses four 10Gbit/s transmission channels to transmit data. data.

QSFP28 optical module

QSFP28 optical module is mainly used in 100G Ethernet and EDR InfiniBand applications, it uses four 25Gbit/s transmission channels to transmit data. Sometimes this optical module is also called QSFP100 or 100G QSFP optical module.

Factors to consider when purchasing optical modules

When purchasing an optical module, the following five points are important considerations:

Transmission distance

The transmission distance supported by different optical modules is different. Generally speaking, the transmission distance of a multi-mode optical module is much shorter than that of a single-mode optical module, and the price is also cheaper. For example, a 10GBASE-SR SFP+ optical module The farthest transmission distance can only reach 400m, but the transmission distance of a 10GBASE-LR SFP+ optical module can reach 10km, so it is very important to figure out the transmission distance you want to achieve. In addition, considering the attenuation and dispersion of the optical signal during transmission, it is recommended that you use an optical module whose transmission distance is slightly greater than the actual requirement. For short-distance connections between devices in the rack, it is recommended that you use high-speed cables that are cheaper than optical modules.

transfer mode

Optical modules mainly have three data transmission methods: simplex, half-duplex and full-duplex. Simplex transmission only supports data transmission in one direction; half-duplex transmission allows data transmission in two directions, but at a certain moment Only data transmission in one direction is allowed; full-duplex transmission allows data transmission in both directions simultaneously. It is best to choose an optical module that supports full-duplex transmission.

Transmission medium

Copper cable and optical cable are the two most widely used transmission media at present. Therefore, some optical modules are designed with electrical ports, and some optical modules are designed with optical ports. Generally speaking, optical port optical modules are commonly used in 10G and 40G Ethernet transmission applications, while electrical port optical modules are used in 100M and Gigabit Ethernet applications, and the transmission distance of optical port optical modules is generally longer than that of electrical port optical modules. Far.

heat resistance

The temperature of the working environment of the optical module should not be too high. If the temperature exceeds the temperature that the optical module can withstand, link failure is likely to occur. Therefore, optical modules with good heat resistance should be selected.

The above points are just the factors that often need to be considered when purchasing optical modules. In addition, the working wavelength, working speed, manufacturer's brand and other aspects also need to be considered.