Optical fiber cables can transmit data from a few hundred meters up to tens of thousands of kilometers, depending on fiber type, network design, and amplification.

Practical Distances by Fiber Type

• Multimode Fiber (MMF): Typically used for short-range applications such as data centers and campus networks. Distances range from 300 meters to 2 kilometers, depending on the fiber grade and data rate. For example, OM2 fiber supports up to 550 meters at 1 Gbps, while OM3/OM4 fibers can reach 300–600 meters at 10 Gbps .

• Single-Mode Fiber (SMF): Designed for long-distance transmission, single-mode fiber can carry signals over 100 kilometers without amplification. With dispersion compensation and amplification, distances can extend to 200 kilometers or more in terrestrial networks, and thousands of kilometers in submarine cables .

Long-Haul and Submarine Applications

• Terrestrial Long-Haul Networks: Using Erbium-doped fiber amplifiers (EDFAs), single-mode fiber can span 240+ kilometers unamplified, with total unregenerated distances reaching up to 2,000 kilometers .

• Submarine Cables: Fiber pairs in undersea cables typically have 50–100 kilometer repeater spacing, enabling intercontinental connectivity over 10,000 kilometers or more .

Factors Affecting Distance

1. Attenuation: Signal loss over distance, measured in dB/km. Lower attenuation allows longer spans. Modern low-loss fibers can achieve 0.16–0.5 dB/km at 1550 nm .
2. Dispersion: Modal and chromatic dispersion can limit high-speed transmission, especially in multimode fibers .
3. Amplification and Regeneration: Use of EDFAs or repeaters extends practical distances significantly .
4. Connectors and Splices: Each connection introduces minor signal loss, affecting maximum reach .

Summary

• Short-range: Multimode fiber, up to 2 km.
• Medium-range: Single-mode fiber, 100–200 km without amplification.
• Long-haul: Single-mode fiber with amplification, 2,000 km or more.
• Submarine/Intercontinental: Single-mode fiber with repeaters, 10,000 km+.

The actual distance achievable depends on fiber type, data rate, network design, and use of amplification technologies, making single-mode fiber the preferred choice for long-distance and high-speed communication networks .