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When deploying optical modules, selecting the appropriate patch cord is crucial. It directly impacts the stability, performance, and ease of future maintenance of the network link. We once encountered a customer who had purchased the correct optical modules but used the wrong patch cords — mixing single-mode and multi-mode — rendering the setup unusable. Therefore, this article will guide you through a systematic understanding of how to choose the correct patch cord type based on optical modules of different speeds (1G, 10G, 25G).
Key Selection Criteria of Fiber Patch Cables
- Fiber Type
- Single-mode Fiber (SMF): suitable for long-distance transmission, typical specifications for OS2, can support from 10km to more than 80km.
- Multimode Fiber (MMF): suitable for short-distance transmission, common specifications for OM1, OM2, OM3, OM4, OM5, of which OM3/OM4/OM5 support higher bandwidth and longer distance.
- Connector Type
- LC: The most common small duplex connector for 1G/10G/25G optical modules
- SC: Commonly used in early 1G optical module systems with a larger size.
- MPO/MTP: Suitable for high-density parallel transmission, such as 100G, 400G, and other modules.
- Application & Distance
- Data Center (Short-distance): Use multimode patch cable (OM2/OM3/OM4/OM5)
- Campus or Metro Networks(Long-distance): Use a single-mode patch cable(OS2)
Recommended Fiber Patch Cables by Speed
1G SFP Optical Module
| Transmission Distance | Recommended Patch Cord Type | Description |
| ≤ 5 meters | Direct Attach Cable (DAC) | Cost-effective, ideal for short direct links |
| ≤ 300 meters | Multimode OM2 / OM3 + LC-LC | Common in data centers for short-range high-bandwidth connections |
| > 300 meters | Singlemode OS2 + LC-LC | Suitable for campus networks, metro networks, and long-haul backbone links |
10G SFP+ Optical Module
| Transmission Distance | Recommended Patch Cord Type | Notes |
| ≤ 7 meters | DAC (Direct Attach Cable) | Ideal for short-range, cost-effective connections |
| ≤ 100 meters | Cat6a / Cat7 Ethernet Cable (for 10GBASE-T modules) | Standard twisted pair cables for 10GBASE-T |
| ≤ 300 meters | OM3 (up to 300m) / OM4 (up to 400m) Multimode + LC-LC | Suitable for short-distance optical links |
| > 300 meters | OS2 Singlemode + LC-LC (supports 10–80 km) | Recommended for long-distance transmission |
25G SFP28 Optical Module
| Transmission Distance | Recommended Patch Cord Type | Notes |
| ≤ 5 meters | DAC (Direct Attach Cable) | Cost-effective for very short, direct connections |
| ≤ 100 meters | OM4 (up to 100m) / OM3 (up to 70m) Multimode + LC-LC | Ideal for short-range optical links |
| > 100 meters | OS2 Singlemode + LC-LC (supports 10–40 km) | Suitable for long-distance, high-speed links |
Application Recommendations
- Data centers recommend OM4 fiber optical patch cables to improve stability.
- OS2 fiber optical patch cables are used for long-distance connections on campus.
- It is recommended to give priority to high-quality, low-loss optical fiber to ensure a controllable BER.
Summary
| Speed | Connector Type | Transmission Distance(<100m) | Transmission Distance(100~300m) | Transmission Distance(>300m) |
| 1G | LC | OM2 | OM3 | OS2 |
| 10G | LC | OM3/OM4 | – | OS2 |
| 25G | LC | OM4 | – | OS2 |
| all | DAC/AOC | ≤30m direct connection | – | – |
Pro Tips When Buying Patch Cables
- Ensure wavelength compatibility: Match fiber patch cable type to transceiver wavelength (e.g., 850nm for multimode, 1310nm for single-mode).
- Consider future scalability: Choose higher-spec fiber patch cables when possible (e.g., OM4 instead of OM3) to better support future network upgrades.
- Check vendor compatibility: Stick to trusted brands or verified compatible cables to prevent interoperability issues.
Can You Mix Single-mode and Multimode Fiber Patch Cables?
No. Even though LC connectors physically fit both, the optical characteristics differ:
| Attribute | Multimode Fiber | Singlemode Fiber |
| Core Diameter | Large (50/62.5μm) | Small (~9μm) |
| Light Source | VCSEL / LED | Laser (DFB/EML) |
| Wavelength | 850nm | 1310nm / 1550nm |
| Distance | <500m | Up to 100km+ |
Mismatching fiber types can lead to:
- The physical interface is compatible, but optical signals are not
LC connectors may look the same, but the transmission mechanisms are different. Mixing them can lead to severe signal loss or complete link failure. - Fiber core diameters don’t match
Multimode fibers have larger cores, while single-mode fibers have much smaller ones. Connecting a single-mode fiber to a multimode system causes significant signal scattering and attenuation. - Wavelength mismatch
Multimode modules typically operate at 850nm, while single-mode modules use 1310nm or 1550nm. These mismatched wavelengths lead to transmission errors or total signal loss. - Device compatibility issues
Even if you can physically connect the cables using a “compatible” patch cord, mismatched optical parameters prevent proper communication and may still cause the link to fail.
The Only Exception: Special Conversion Solutions
If communication between single-mode and multimode devices is necessary, you can use a multimode-to-single-mode converter (such as a media converter or duplex fiber transceiver). However, this adds cost and complexity to the network and is not recommended as a standard solution.
Conclusion
Multimode and single-mode fiber patch cables are not interchangeable; avoid the temptation to mix them—it may result in unstable connections, high error rates, or even damage to your transceivers. Don’t mix single-mode and multimode patch cables. When in doubt, send us your module model or SKU—we’re happy to help verify compatibility.
