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What is the difference between 25G LWDM and 25G MWDM optical modules?
Knowledge Base + 2024.01.25

For WDM wavelength division multiplexing technology, we generally common CWDM coarse wavelength division multiplexing and DWDM dense wavelength division multiplexing, so the CWDM optical module and DWDM optical module is also more familiar with the most commonly used.

25G SFP28 LWDM Optical Module

25G SFP28 LWDM optical module adopts LWDM (LAN WDM) thin WDM technology (O-band), with 12 wavelengths, eight of which are standard wavelengths in accordance with the 800GHz division of the O-band spectrum, and the remaining four wavelengths are multiplexed with the four wavelengths of the 25G CWDM module, which are 1269.23nm, 1332.41nm, 1332.41nm, 1332.41nm, 1332.41nm, 1332.41nm, 1332.41nm, 1332.41nm, 1332.41nm and 1332.41nm. The wavelength spacing is 4 nm, which is much narrower than that of the 25G CWDM optical module, and thus generates a large wavelength offset. There is another influencing factor regarding the wavelength offset. Under normal circumstances, the operating temperature of SFP28 LWDM optical module is -40℃ to 85℃, and the transmission distance is 10KM-40KM.

The LWDM optical module is also capable of multiple signal transmission on a single fiber like other 25G WDM optical modules, and it costs less, mainly in its structural design. Compared with SFP28 CWDM optical module, the wavelength of SFP28 LWDM optical module is located in the low dispersion region, and only a PIN receiver can be used at the receiving end to meet the transmission requirements; compared with SFP28 DWDM optical module, SFP28 LWDM optical module is not necessarily an EML laser, and a relatively inexpensive DML laser can be used.

25G SFP28 MWDM Optical Module

25G SFP28 MWDM optical module adopts MWDM (Metro WDM) medium wavelength division multiplexing (MWDM) technology, on the basis of using the first 6 waves of SFP28 CWDM, the center wavelength is shifted by 3.5nm, 12 wavelengths are realized by using DFB laser (with TEC), the light-emitting power ranges from 0-6dBm, and the receiving end has a sensitivity of -14dBm, and the maximum power consumption is less than 2W. With a maximum power consumption of less than 2W, it can realize a transmission distance of 10KM to meet industrial-grade scenarios.

It is worth mentioning that SFP28 MWDM optical module combines optical layer topping technology, realizes OAM mechanism, and has functions such as remote optical protection, communication fault location, service performance detection, etc., which can effectively improve the efficiency of network system management and operation and maintenance. At the same time, there are two types of receiver configuration options, APD and PIN, which can meet the user to increase the optical path protection inversion or a larger link language segment under the circumstances of the application needs.

Additional Learning Hub Resources 

SFP Optical Module Wiki 

CSFP Optical Module Wiki 

QSFP-DD Optical Module Wiki 

QSFP28 Optical Module Wiki 

QSFP Optical Module Wiki 

Tunable SFP+ Transceiver Wiki 

10G BIDI SFP+ Optical Modules Wiki 

DWDM SFP+ 10G Optical Module Wiki 

CWDM SFP+ 10G Optical Module Wiki 

Video SFP Optical Module Wiki 

BIDI-SFP Optical Module Wiki 

DWDM SFP Optical Module Wiki