40G QSFP+ optical modules are mainly divided into three types: QSFP+ 40G SR4, QSFP+ 40G LR4 and QSFP 40G PSM4, and their transmission rates are all 40G.
QSFP+ 40G SR4 optical module
QSFP+ 40G SR4 optical modules are often used with MPO/MTP connectors to connect to multi-mode optical fibers. The working wavelength is 850nm, and the longest transmission distance can reach 300m, which is suitable for short-distance transmission.
QSFP+ 40G LR4 optical module
The QSFP+ 40G LR4 optical module is often used by connecting 2 single-mode fibers with an LC duplex interface. The working wavelength is 1271 1291 1311 1331nm, and the transmission distance can reach up to 10km.
QSFP+ 40G PSM4 optical module
QSFP+ 40G PSM4 optical modules are often used with MPO/MTP connectors. The working principle is the same as SR4. The difference is that it connects 8 single-mode fibers and runs in parallel. The working wavelength is 1310nm and the maximum transmission distance is up to 10km.