Single-Mode vs Multi-Mode Optical Fiber: How to Choose? Clarify the Core Differences in One Article

In optical cable selection, the choice between single-mode and multi-mode optical fibers is one of the core decisions. There are significant differences between the two in terms of transmission distance, bandwidth and cost. Wrong selection will not only affect network performance but also may lead to difficulties in later upgrades. Many users will fall into the misunderstanding that "single-mode is better" or "multi-mode is cheaper". In fact, the key is to match the actual application needs.

The core diameter of single-mode optical fiber is only 9µm, with extremely long transmission distance and almost unlimited bandwidth, making it the only choice for park backbones and long-distance communication. Among them, B6.a (G.657.A2) bend-insensitive single-mode optical fiber has become the default recommendation for new projects due to its adaptation to complex wiring environments. The core diameter of multi-mode optical fiber is 50/62.5µm, with short transmission distance, but the cost of optical modules is low. It is only suitable for intra-cabinet or short-distance intra-building connections in data centers. The current mainstream models are OM4 and OM5, which support higher rate transmission. Three principles can be followed when selecting: prioritize single-mode if the transmission distance exceeds 500 meters, and consider multi-mode if it is less than 300 meters; choose single-mode for high-bandwidth requirements (10G/100G+), and mid-to-high-end multi-mode for medium-to-low bandwidth (1G/10G); from the perspective of total cost of ownership, the long-term cost of single-mode systems may be lower, and multi-mode is more suitable for scenarios sensitive to initial investment.

There is no absolute advantage or disadvantage between single-mode and multi-mode. Only by comprehensively judging the transmission distance, bandwidth requirements and cost budget can the optimal choice be made.