Comparison of the differences between 25G LWDM and 25G MWDM optical modules

For WDM wavelength division multiplexing technology, CWDM coarse wavelength division multiplexing and DWDM dense wavelength division multiplexing are commonly used, so CWDM optical modules and DWDM optical modules are also familiar and most commonly used. In this article, ETU-LINK will talk about the relatively rare 25G LWDM optical modules and 25G MWDM optical modules.

The 25G SFP28 LWDM optical module adopts LWDM (LAN WDM) fine wavelength division multiplexing technology (O-band), and has 12 wavelengths, of which eight wavelengths are standard wavelengths that divide the O-band spectrum according to 800GHz, and the remaining four The wavelength is multiplexed with four wavelengths of the 25G CWDM optical module, which are 1269.23nm, 1332.41nm, 1313.73nm and 1291.10nm. The wavelength interval is 4nm, which is much narrower than that of the 25G CWDM optical module, so there will be a large wavelength shift. Regarding the wavelength shift, there is another factor. Under normal circumstances, the operating temperature of the SFP28 LWDM optical module is -40°C to 85°C, and the transmission distance is 10KM-40KM.

Like other 25G WDM optical modules, LWDM optical modules can also realize multiple signal transmission on one optical fiber, and its cost is lower, mainly in its structural design. Compared with the SFP28 CWDM optical module, the wavelength of the SFP28 LWDM optical module is located in the low dispersion area, and only the PIN receiver can be used at the receiving end to meet the transmission requirements; compared with the SFP28 DWDM optical module, the SFP28 LWDM optical module does not have to use EML. For lasers, relatively inexpensive DML lasers can be used.

The 25G SFP28 MWDM optical module adopts MWDM (Metro WDM) medium wavelength division multiplexing technology. On the basis of using the first 6 waves of SFP28 CWDM, the center wavelength is shifted left and right by 3.5nm, and the DFB laser (with TEC) is used to achieve 12 wavelengths. The luminous power range is 0-6dBm, the receiving end sensitivity is -14dBm, the maximum power consumption is less than 2W, and the transmission distance is 10KM, which meets the application of industrial-grade scenarios.

It is worth mentioning that the SFP28 MWDM optical module combines the optical layer top adjustment technology to realize the OAM mechanism, and has functions such as remote optical path protection, communication fault location, service performance detection, etc., which can effectively improve the efficiency of network system management, operation and maintenance. At the same time, there are two receiver configuration options of APD and PIN, which can meet the application requirements of users when adding optical path protection switching or larger link segments.