• Overview
        With the development of technology, people's speed requirements for fiber optic communication are also increasing, and currently 100G optical modules are also applied in various scenarios. There are various packaging forms for 100G optical modules, including CFP, CFP2, CFP4, CXP, and QSFP28. Among these different packaging forms, QSFP28 optical modules have become the main packaging form for 100G optical modules due to their small size, high port density, and low cost advantages, and have been favored by various enterprises, operators, and data centers.
 • QSFP28 optical modules classification and application
1. QSFP28 SR4 optical module
        The QSFP28 SR4 optical module is based on the 100G Ethernet IEEE 802.3bm standard. This product provides four independent sending and receiving channels, each supporting 25G, with a total bandwidth of 100G. The center wavelength is 850nm and uses an MPO interface. It can transmit 70m on OM3 multimode fiber and 100m on OM4 multimode fiber, making it suitable for short distance transmission. Due to its characteristics, the QSFP28 SR4 optical module is often used in data centers, paired with multimode fiber optic for inter switch wiring within a distance of 100m.
2. QSFP28 LR4 optical module
        The QSFP28 LR4 optical module is based on the 100G Ethernet IEEE 802.3ba standard. Unlike the QSFP28 SR4, the QSFP28 LR4 optical module uses WDM technology, which multiplexes different wavelengths of four fiber channels onto a single fiber for transmission. The center wavelengths of the four LAN WDM channels are 1295.56, 1300.05, 1304.58, and 1309.14nm, respectively. The module uses dual LC interfaces and can transmit up to 10km in conjunction with single mode fiber. Suitable for medium to long distance transmission applications, mostly used in large data centers and enterprise parks.

QSFP28-SR4 and QSFP28-LR4 optical modules of Moduletek Limited
 

Figure 1 QSFP28-SR4 and QSFP28-LR4 optical modules of Moduletek Limited

3. QSFP28 PSM4 optical module
        The QSFP28 PSM4 optical module is similar to the QSFP28 SR4 in that it provides four independent transmission and reception channels and uses an MPO interface. However, the difference is that the center wavelength of the QSFP28 PSM4 optical module is 1310nm, and when used with single-mode fiber, the maximum transmission distance can reach 2km. It should be noted that the QSFP28 PSM4 optical module of Moduletek Limited uses an MPO socket with an 8-degree angle end face to minimize reflections caused by MPO connections. This product should use a female MPO connector with an 8-degree end face.
4. QSFP28 CWDM4 optical module
        The QSFP28 CWDM4 optical module is similar to the QSFP28 LR4 in that it uses WDM technology to convert four 25Gb/s electrical data input channels into four CWDM optical signals, and multiplexes them into a single channel to achieve 100Gb/s optical transmission. Similarly, at the receiving end, the module decomposes and multiplexes the 100Gb/s input light into four CWDM channel signals, and converts them into four channel output electrical data. The center wavelength of the four channels is 1271,1291,131,11331nm, using LC interface and combined with single mode optical fiber, it can transmit 2km.
5. QSFP28 ER4 Lite optical module
        The QSFP28 ER4 Lite optical module is based on the 100G Ethernet IEEE 802.3bm standard, similar in principle to the QSFP28 LR4 optical module. It converts four 25Gb/s electrical signals into four LAN-WDM wavelength optical signals, and couples them into a single fiber through an internal multiplexer (MUX) to complete 100Gb/s optical signal transmission. But the difference is that the QSFP28 ER4 Lite optical module uses an APD receiver, which is suitable for long-distance transmission. If the host used has FEC function, the QSFP28 ER4 Lite can transmit up to 40km on the single mode fiber of the optical module. If the host used does not have FEC function, the maximum transmission distance is 30km.
        Moduletek Limited provides the products involved in the above application guide, welcome everyone to choose.
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