The difference of 100G CWDM4 and 100G PSM4

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The 100G PSM4 standard was developed by the MSA (Multi-Source Agreement) group, which defines a low-cost solution for transmitting four 25Gbps wavelengths over single-mode fiber in addition to the IEEE 100G Ethernet specification, enabling long-distance data centers. The interconnection is specially designed for network applications with a transmission distance of 500M and 2KM. The purpose is to provide a parallel single-mode infrastructure for the service requirements of the next-generation data center.

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100G QSFP28 PSM4 optical module is usually used with an MPO single-mode OS2 fiber patch cord, and the transmission distance can reach 500M or 2KM.

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1.The optional transmission distance of the two is different. 100G QSFP28 PSM4 has 500m, 2km, and 10km transmission distance optional, while the transmission distance of 100G QSFP28 CWDM4 is only up to 2km.

2. The fiber types used by the two are different. 100G QSFP28 PSM4 needs to use ribbon single-mode MPO fiber jumpers (8 cores) for connection, while 100G QSFP28 CWDM4 uses duplex single-mode LC fiber jumpers for connection.

3. The optical fiber connectors of the two are different, 100G QSFP28 CWDM4 is a duplex LC interface, and 100G QSFP28 PSM4 is an MPO interface.

4. The center wavelengths of the two are different. The center wavelength of 100G QSFP28 CWDM4 is 1271, 1291, 1311, and 1331nm, while the center wavelength of 100G QSFP28 PSM4 is 1310nm.

5. The laser devices used by the two are different. The optical transmitter of 100G QSFP28 PSM4 is composed of four integrated silicon photonic modulators and a distributed feedback laser, while the optical transmitter of 100G QSFP28 CWDM4 is four CWDM uncooled DFB lasers. .

6. 100G QSFP28 CWDM4 requires a 4-wavelength CWDM multiplexer/demultiplexer, while 100G QSFP28 PSM4 does not.

7. The working principles of the two are different. The 100G QSFP28 CWDM4 adopts the coarse wavelength division multiplexing technology to multiplex 4 different wavelengths into a single-mode fiber for transmission, while the 100G QSFP28 PSM4 adopts the parallel transmission technology. The same wavelength is transmitted using 4 separate single-mode fibers.

8. The cost of the two is different. The structure of 100G QSFP28 CWDM4 is more complicated than that of 100G QSFP28 PSM4, and the manufacturing cost is higher, so the price is relatively high.