What does mm mean in optical module

"MM" in an optical module stands for Multi-Mode, indicating that the module is designed to work with multi-mode optical fiber, which supports multiple light paths simultaneously.Definition and CharacteristicsIn optical modules, MM refers to multi-mode fiber, which has a larger core diameter (typically 50 or 62.5 microns) compared to single-mode fiber (around 9 microns) and allows multiple modes, or paths, of light to propagate at the same time . This design enables the transmission of optical signals over shorter distances with high data rates, making MM fibers suitable for local area networks (LANs), data centers, and short-haul telecom links .Core and TransmissionThe larger core of MM fiber permits multiple light modes, which can lead to modal dispersion over long distances, limiting the effective transmission range . MM optical modules are typically used with 850 nm wavelength light, whereas single-mode (SM) modules use longer wavelengths like 1310 nm or 1550 nm . MM modules are marked as MLM, while SM modules are marked as SLM to indicate compatibility with the corresponding fiber type .ApplicationsMulti-mode optical modules are commonly used in:Ethernet networks and fiber-to-the-home (FTTH) systemsCampus or building backbone networksAudio/video transmission linksShort-distance high-bandwidth applications MM fibers are cost-effective and easier to connect than single-mode fibers, making them ideal for environments where high-speed data transmission over moderate distances is required .Key TakeawayWhen you see "MM" on an optical module, it indicates that the module is designed for multi-mode fiber, which supports multiple light paths, has a larger core, and is optimized for short-distance, high-bandwidth communication. It is important to match MM modules with MM fiber to ensure proper signal transmission and avoid compatibility issues .