What is difference between single-mode and multimode fiber?

Difference Between Single-Mode and Multimode Fiber

Single-mode and multimode fibers are two primary types of fiber optic cables, each designed for specific applications and offering distinct advantages and limitations. The core difference lies in the mode of light propagation and the fiber's core diameter, affecting bandwidth, distance, and overall performance.

Core Diameter and Light Propagation

Single-mode fiber has a small core diameter, typically around 9 micrometers, allowing only one mode of light to propagate directly down the fiber. This design minimizes signal degradation over long distances, making it ideal for telecommunications and high-speed broadband networks.

Multimode fiber, on the other hand, has a larger core diameter, ranging from 50 to 62.5 micrometers, which supports multiple modes of light. This design enables light to travel through the core in different paths, leading to modal dispersion and a reduction in signal quality over long distances.

Bandwidth and Distance

Single-mode fiber offers a higher bandwidth and can transmit data over longer distances (up to 100 kilometers) without significant signal loss, thanks to its ability to prevent modal dispersion.

Multimode fiber is suited for shorter distances, typically up to 500 meters for data applications and up to 2 kilometers for less demanding applications, due to modal dispersion and lower bandwidth capabilities.

Applications

Single-mode fiber is primarily used in long-distance applications, such as long-haul telephony and cable television networks, where high bandwidth and minimal signal attenuation are required.

Multimode fiber is commonly used in short-distance applications, such as within buildings or on campuses, where high bandwidth and high-speed data transmission are needed over short distances.

Cost Considerations

While single-mode fiber has a higher initial cost due to its specialized equipment, it is more cost-effective for long-distance applications due to its superior performance and lower overall maintenance costs.

Multimode fiber is less expensive upfront and is preferred for short-range applications where the higher cost of single-mode fiber cannot be justified.