Can 850nm and 1310nm optical modules be used together?

I. Core Conclusion

• Wavelength mismatch The transmission wavelength of the optical module must match the receiving wavelength of the receiver. For example, if one end sends an 850nm signal, the other end must use an optical module that supports 850nm reception, and vice versa.
• Optical fiber type limitations 850nm is typically used for multi-mode fiber (MMF), while 1310nm is mostly used for single-mode fiber (SMF). Mixing wavelengths may result in excessive signal attenuation or inability to transmit.

• WDM technology Uses a multiplexer/demultiplexer to multiplex 850nm and 1310nm signals onto the same fiber, suitable for data center interconnection, etc.
• Tunable optical modules Supports optical modules that dynamically switch wavelengths (such as 25G Tunable DWDM), requiring a wavelength division multiplexer to achieve multi-wavelength transmission.

II. Detailed Analysis

1. Wavelength and fiber type compatibility

• Applicable scenarios Multi-mode fiber (OM1/OM2/OM3/OM4), shorter transmission distances (e.g., Gigabit multi-mode 550 meters, 10 Gigabit multi-mode 300 meters).
• Features Low cost, but severe modal dispersion, not suitable for long distances.

• Applicable scenarios Single-mode fiber (G.652), transmission distance can reach over 40 kilometers.
• Features Low dispersion, suitable for long-distance transmission, but higher cost.

• 850nm has extremely high attenuation in single-mode fiber (approximately 2.5-3.0dB/km) and cannot be effectively transmitted.
• Although 1310nm can be transmitted in multi-mode fiber, the bandwidth is limited, and practical applications are rare.

2. Obstacles to direct sharing

3. Indirect sharing technical solutions

• Principle Combines 850nm and 1310nm signals into the same fiber using a multiplexer, and a demultiplexer separates the signals at the receiving end.
• Application scenarios Short-distance interconnection in data centers (such as simultaneously transmitting 850nm and 1310nm in OM4 multi-mode fiber), 5G fronthaul, etc.
• Limitations Requires additional WDM equipment, higher cost, and limited multiplexing effect of 850nm and 1310nm in multi-mode fiber.

• Principle Supports optical modules that dynamically switch wavelengths (such as 25G Tunable DWDM), which can be adapted to different wavelengths through software configuration.
• Application scenarios Dynamic optical networks, metropolitan area networks, require a wavelength division multiplexer to achieve multi-wavelength transmission.
• Limitations High module cost and requires equipment to support wavelength auto-negotiation.

• Solution Uses two optical fibers to transmit 850nm and 1310nm signals separately, suitable for scenarios with sufficient fiber resources.
• Limitations Increases fiber usage and wiring costs.

III. Typical Scenario Examples

Scenario 1: Short-distance transmission over multi-mode fiber

• Requirements Two devices are connected via multi-mode fiber, one end using an 850nm optical module and the other end using a 1310nm optical module.
• Result Cannot communicate; needs to be replaced with optical modules of the same wavelength (e.g., both 850nm).

Scenario 2: Long-distance transmission over single-mode fiber

• Requirements Two devices are connected via single-mode fiber, one end using an 850nm optical module and the other end using a 1310nm optical module.
• Result The 850nm signal has excessive attenuation in single-mode fiber and cannot be transmitted; needs to be replaced with a 1310nm optical module.

Scenario 3: Multi-wavelength multiplexing in data centers

• Requirements Transmit 850nm (10 Gigabit Ethernet) and 1310nm (Gigabit Ethernet) signals simultaneously in OM4 multi-mode fiber.
• Solution Use a wavelength division multiplexer (such as CWDM) to multiplex the two wavelengths onto the same fiber. The devices at both ends are configured with corresponding optical modules and demultiplexers.
• Limitations Ensure that the optical modules support WDM wavelengths and that the total loss after multiplexing is within the receiving sensitivity range of the equipment.

Summary and Suggestions

• WDM technology Suitable for multi-wavelength multiplexing scenarios, but requires additional equipment.
• Tunable optical modules Suitable for dynamic networks, but higher cost.

• Prioritize Wavelength Matching Select optical modules with the corresponding wavelength based on the fiber type and transmission distance.
• Avoid Mixing If upgrading the network, it is recommended to uniformly replace them with optical modules of the same wavelength.
• Consult Equipment Manufacturers Confirm whether the switches, routers, and other equipment support WDM or tunable optical modules.