Question

What is the maximum distance for fiber-optic cable?

Answer 1

The maximum distance for a fiber-optic cable depends on several factors, such as the type of fiber, the data transmission speed, and whether any signal amplification or regeneration is used. Here's a general idea:

1. Single-mode fiber:
   

   - Maximum distance: 40-80 kilometers (km) without repeaters or amplifiers for high-speed transmission (like 10 Gbps or higher).
   - With the use of optical amplifiers (like erbium-doped fiber amplifiers), the distance can reach up to 100 km or more.
   - Single-mode fiber is ideal for long-distance communication as it uses a single light path, minimizing loss and distortion.

1. Multi-mode fiber:
   

   - Maximum distance: Typically, around 300 meters to 2 km, depending on the transmission speed (higher speeds result in shorter distances).
   - Multi-mode fiber is used for shorter distances due to higher signal loss compared to single-mode fiber. It uses multiple light paths, which causes greater dispersion and reduces the effective transmission distance.

Factors affecting the maximum distance:

1. Signal loss (attenuation): Over long distances, the signal weakens. The type of fiber and the wavelength of light used (e.g., 850 nm, 1310 nm, or 1550 nm) influence how much the signal weakens.
   

1. Dispersion: In multi-mode fiber, signal dispersion increases with distance, which can degrade signal quality.
   

1. Amplifiers: Using optical amplifiers can extend the range of the signal by boosting its strength over long distances.
   

In practical scenarios, fiber optic networks are often designed with repeaters or amplifiers to ensure the signal stays strong over very long distances.