How to choose fiber type for data-center links — reach, cost trade-offs, jacket colors and why the fiber must match the module.
Updated October 2026 · AltoChip team · General reference — project specifics are confirmed in each quotation.
Multimode modules (SR family) run on multimode fiber; single-mode modules (DR, FR, LR) run on single-mode fiber. Mixing them does not work reliably even if the connector fits. If you already have structured cabling, the installed fiber type usually decides the module family.
| Grade | Type | Typical jacket color | Notes |
|---|---|---|---|
| OM3 | Multimode 50/125 | Aqua | Shorter SR reach |
| OM4 | Multimode 50/125 | Aqua or violet | Most common for new SR links |
| OM5 | Multimode 50/125, wideband | Lime green | Designed for shortwave WDM optics |
| OS2 | Single-mode 9/125 | Yellow | DR / FR / LR, longest reach |
Jacket colors are industry conventions, not guarantees — check the print on the cable.
Many AI and spine fabrics now standardize on single-mode (DR/FR) for flexibility as speeds rise; multimode SR optics remain cost-effective for short in-row links. We quote either — the decision follows your distance, existing cabling and roadmap.