The wavelength of a 100G SFP (Small Form-Factor Pluggable) transceiver module can vary depending on the specific type and standard. There are different variants of 100G SFP modules, each designed for specific applications and operating over different wavelengths. The most common types include:

1. 100GBASE-SR4:

• Wavelength: 850 nm (nanometers)

• Application: Short-Range (SR) applications, typically used for connections within a data center.

2. 100GBASE-LR4:

• Wavelength: 1310 nm

• Application: Long-Range (LR) applications, suitable for longer-distance connections in metro and enterprise networks.

3. 100GBASE-ER4:

• Wavelength: Multiple wavelengths around 1310 nm

• Application: Extended-Range (ER) applications, designed for even longer-distance connections.

4. 100GBASE-CWDM4:

• Wavelengths: Specific wavelengths in the CWDM (Coarse Wavelength Division Multiplexing) grid, typically from 1271 nm to 1331 nm.

• Application: CWDM applications, providing multiple channels for increased capacity.

5. 100GBASE-PSM4:

• Wavelengths: Multiple wavelengths around 1310 nm

• Application: Parallel Single-Mode (PSM) applications, used for short- to medium-distance connections in data centers.

It's important to note that these wavelength specifications are general guidelines, and the exact wavelengths may vary between different manufacturers and specific implementations. When selecting a 100G SFP module for a particular application, it's crucial to refer to the datasheets and documentation provided by the module manufacturer for accurate information on wavelength, reach, and compatibility.