The transmission distance of the optical module is divided into three types: short distance, medium distance and long distance. Optical Modules are categorized by their reach capabilities: Note: CWDM/DWDM modules enable longer distances through wavelength division multiplexing. These labels also hint at the typical. Optical module classification By package: 1*9, GBIC, SFF, SFP, XFP, SFP+, X2, XENPARK, 300pin, etc. By wavelength: conventional wavelength, CWDM, DWDM, etc. By mode: single-mode fiber (yellow), multi-mode fiber (orange-red). Its primary function is to achieve optoelectronic conversion by converting electrical signals into optical signals and vice versa.