Several ways to classify optical modules

Optical modules can be classified by data rate, form factor, transmission distance, wavelength, modulation format, interface type, and WDM support.1. Classification by Data RateOptical modules are often categorized based on the maximum transmission rate of a single port. Common rates include 1.25Gbps (1GE), 10Gbps (10GE), 25/28Gbps, 40Gbps, 100Gbps, 200Gbps, 400Gbps, 800Gbps, 1.6Tbps, and higher for emerging standards. The single-pair differential rate multiplied by the number of sending or receiving pairs determines the total port bandwidth .2. Classification by Form FactorForm factor refers to the physical size and interface of the module, affecting compatibility with network equipment. Common types include:SFP (Small Form-factor Pluggable): up to 1 GbpsSFP+: up to 10 GbpsSFP28: 25 GbpsQSFP/QSFP+: 40 GbpsQSFP28: 100 GbpsQSFP-DD: 400–800 GbpsCFP/CFP2/CFP4: 40–400 GbpsOSFP/OSFP-XD: 800 Gbps–1.6Tbps Older modules include GBIC for lower rates .3. Classification by Transmission DistanceModules are also classified by reach:Short-range (SR): typically multi-mode fiber, up to 300 metersLong-range (LR): single-mode fiber, several kilometersExtended-range (ER/XR): tens of kilometersUltra-long-range (ZR): 80–120 km or more Wavelength division multiplexing (WDM) modules, such as CWDM and DWDM, enable longer distances by transmitting multiple signals over a single fiber .4. Classification by Wavelength and ModulationWavelength: Modules can operate at different wavelengths (e.g., 850nm, 1310nm, 1550nm) depending on fiber type and distance.Modulation format: NRZ, PAM4, CWDM, DWDM, and PSM. PAM4 reduces laser and detector costs but requires more complex signal processing .5. Classification by Interface and Transmission ModeTOSA/ROSA: Transmitting and receiving optical sub-assembliesBOSA (Bi-Directional Optical Sub-Assembly): Combines TOSA and ROSA for single-fiber bidirectional transmissionSingle-fiber bidirectional (BiDi): One fiber supports simultaneous transmission and reception, reducing fiber usage .6. Classification by Additional FeaturesDigital Diagnostic Monitoring (DDM): Monitors voltage, temperature, optical power, and laser bias currentOperating temperature: Commercial, industrial, or extended temperature rangesPurpose: Enterprise, data center, metro, or long-haul networks . By considering these classification criteria, network designers can select optical modules that optimize performance, cost, and compatibility for specific applications.