What wavelength should be chosen for multimode optical cables

For multimode optical fibers, the standard and most widely used wavelength is 850 nm, with some applications extending to 1300 nm for specific scenarios.

Optimal Wavelength Selection

850 nm is the primary wavelength for multimode fibers because it allows the use of low-cost light sources such as LEDs and vertical-cavity surface-emitting lasers (VCSELs), which are efficient for short- to medium-distance data transmission in enterprise networks and data centers . This wavelength also exhibits lower attenuation in multimode fibers, enabling longer transmission distances compared to other wavelengths within the multimode range . 1300 nm can also be used in multimode fibers, particularly for legacy systems or when slightly longer distances are required, but it is less common due to higher cost and reduced compatibility with modern VCSEL-based transceivers .

Fiber Type Considerations

• OM1 and OM2: Typically support 850 nm for short-distance applications (up to 33 meters for OM1 at 1 Gbps) and are compatible with LED sources .
• OM3 and OM4: Laser-optimized multimode fibers (LOMMF) designed for 850 nm VCSELs, supporting 10–100 Gbps over distances up to 300 m (OM3) and 550 m (OM4) in data centers .
• OM5: Supports short-wavelength division multiplexing (SWDM), allowing multiple wavelengths from 850 nm to 940 nm for higher data rates (40–400 Gbps), but standard 850 nm operation remains fully compatible .

Practical Guidance

• For most enterprise and data center applications, choose 850 nm as the operating wavelength.
• Use OM3 or OM4 fibers for high-speed networks (10–100 Gbps) to ensure compatibility with VCSEL transceivers and optimal distance performance.
• Consider OM5 only if planning to implement SWDM for multi-wavelength transmission; otherwise, standard 850 nm operation is sufficient.
• Avoid using multimode fibers for long-distance links where single-mode fiber with 1310 nm or 1550 nm would be more appropriate due to lower attenuation and higher bandwidth over long spans . In summary, 850 nm is the recommended wavelength for multimode optical cables, balancing cost, performance, and compatibility with modern network equipment, while 1300 nm is reserved for specific legacy or extended-distance scenarios.