Wavelength of multimode optical modules

Standard multimode optical modules typically use one wavelength per channel, but OM5 modules can support multiple wavelengths simultaneously using SWDM. Standard Multimode Fibers (OM1–OM4)Traditional multimode fibers, including OM1, OM2, OM3, and OM4, are designed to operate primarily at 850 nm and 1300 nm wavelengths. Each multimode optical module generally transmits light at a single wavelength per channel, either from a VCSEL (Vertical-Cavity Surface-Emitting Laser) or an LED light source.

The 850 nm wavelength is most common for short-range, high-speed data transmission, while 1300 nm is used for slightly longer distances. These fibers allow multiple propagation modes within the core, but the module itself does not use multiple wavelengths simultaneously. OM5 and Short-Wave Division Multiplexing (SWDM)OM5 multimode fiber introduces short-wave division multiplexing (SWDM), which allows a single fiber strand to carry multiple wavelengths simultaneously.

Typically, OM5 supports four wavelengths in the 850–950 nm range, enabling higher aggregate data rates (e.g., 100G, 200G, or 400G) over short distances in data centers. Each wavelength is transmitted independently, effectively multiplying the fiber's capacity without requiring additional strands. This is a key difference from earlier multimode fibers, which are limited to a single wavelength per module.

SummaryOM1–OM4 multimode modules: Usually one wavelength per channel (850 nm or 1300 nm). OM5 multimode modules with SWDM: Can support multiple wavelengths simultaneously (commonly four), increasing data throughput on a single fiber strand. In conclusion, the number of wavelengths in a multimode optical module depends on the fiber type and technology: standard modules use a single wavelength, while OM5 modules can use multiple wavelengths concurrently for higher-capacity applications.