1. QSFP28 SR4 optical module
QSFP28 SR4 optical module adopts MTP interface (8-core), which is suitable for short distance transmission. It belongs to parallel 100G optical module, and has advantages of high port density and low cost.
2. QSFP28 LR4 optical module
QSFP28 LR4 optical module introduces WDM technology and adopts duplex LC interface. When it is used together with single-mode optical fiber, the transmission distance can reach 10km, which provides a solution for the demand of increasing transmission distance for super large data center.
3. QSFP28 PSM4 optical module
QSFP28 PSM4 optical module has the shape of hot swappable QSFP, built-in digital diagnosis function, with the advantages of high speed, low power consumption, mainly used for medium and long-distance transmission applications, using MTP interface.
4. QSFP28 CWDM4 optical module
QSFP28 CWDM4 optical module is mainly used in calculation, high-frequency trading and other fields. WDM technology is also introduced and LC duplex interface is adopted. When used together with single-mode fiber, the transmission distance can reach 2km.
Four common QSFP28 optical module differences
1. Different transmission modes
The QSFP28 SR4 optical module and QSFP28 PSM4 optical module both use 12 channels of MTP interface, and realize the bidirectional 100G transmission of 8 channels of optical fiber.
QSFP28 LR4 optical module and QSFP28 CWDM4 optical module transmit 100G through four independent wavelength channels, and use wavelength division multiplexing technology to multiplex four wavelength signals to a single-mode fiber for transmission.
2. Different transmission medium and transmission distance
QSFP28 SR4 optical module is usually used with MTP multimode fiber. When used with OM3 fiber, the maximum transmission distance is 70m, and when used with OM4 fiber, the maximum transmission distance is 100m.
QSFP28 LR4 optical module is usually used with LC duplex single-mode fiber, and the maximum transmission distance can reach 10km.
QSFP28 PSM4 optical module is usually used with MTP single-mode optical fiber, with transmission distance up to 500m.
QSFP28 CWDM4 optical module is usually used with LC duplex single-mode fiber, and the transmission distance can reach 2km.
3. Different wiring structure
The operation of QSFP28 PSM4 optical module is in single-mode fiber, while QSFP28 SR4 optical module is in multimode fiber.
QSFP28 LR4 optical module and QSFP28 CWDM4 optical module are usually used together with LC duplex single-mode optical fiber patch cord, adopting the dual-pass dual fiber SMF wiring structure.
4. Different working principles
The principle of QSFP28 SR4 optical module and PSM4 optical module is basically the same, the former is on multimode fiber, the latter is on single-mode fiber.
The principle of QSFP28 LR4 optical module and QSFP28 CWDM4 optical module is the same. They convert four 25G electrical signals into four LAN WDM optical signals, and then multiplex them into a single channel to realize 100G optical transmission.
