Multimode fiber is thicker than single-mode fiber, with a larger core diameter that allows multiple light paths.

Core Diameter Differences

Single-mode fiber has a very small core, typically around 8–10 microns, which allows only a single light mode to propagate. This narrow core minimizes signal loss and supports long-distance, high-speed transmission, making it ideal for backbone networks and long-haul communication links . Multimode fiber, in contrast, has a significantly larger core, usually 50 or 62.5 microns, enabling multiple light modes to travel simultaneously. This larger core makes multimode fiber easier to connect and align, but it also introduces modal dispersion, which limits the effective transmission distance to shorter ranges, such as within buildings or data centers .

Implications of Thickness

• Installation and alignment: Multimode fiber's larger core simplifies installation and reduces the precision required for connectors and light sources.
• Distance and performance: Single-mode fiber's smaller core supports ultra-long distances with minimal signal degradation, while multimode fiber is optimized for short-range, high-bandwidth applications.
• Cost considerations: Multimode fiber is generally less expensive for short-distance networks, whereas single-mode fiber requires more precise components and laser-based transceivers, increasing cost .

Summary

In essence, multimode fiber is thicker than single-mode fiber due to its larger core diameter, which allows multiple light paths. Single-mode fiber, with its narrower core, is designed for long-distance, high-performance transmission, while multimode fiber is better suited for short-range, cost-effective network connections .