A single-mode fiber optic cable can support data rates from 1 Gbps up to 100 Gbps or more, depending on distance and technology used.

Single-mode fiber (SMF) is designed with a very small core, typically 8–10 micrometers in diameter, allowing only a single light mode to propagate. This minimizes modal dispersion and enables high-speed transmission over long distances, often exceeding 40 km for 10 Gbps links and up to 80 km for 1 Gbps links without signal regeneration . Modern systems using Dense Wavelength Division Multiplexing (DWDM) can further increase capacity by transmitting multiple wavelengths simultaneously, effectively multiplying the total bandwidth .

Typical Data Rates

• 1 Gbps: Can reach distances up to 80 km without repeaters .
• 10 Gbps: Reliable over 40 km using standard single-mode fiber .
• 40–100 Gbps: Achievable over shorter distances (10 km) with advanced transceivers and DWDM technology .
• Beyond 100 Gbps: Cutting-edge systems in telecom and AI infrastructure can exceed 400 Gbps per fiber using multiple wavelengths and coherent modulation techniques .

Factors Affecting Bandwidth

1. Distance: Longer distances require higher-quality fiber and may need signal amplification or regeneration.
2. Wavelength: Single-mode fibers operate efficiently in the 1310 nm and 1550 nm windows, with lower attenuation at 1550 nm allowing longer reach .
3. Transceiver Technology: The type of laser and modulation method (e.g., NRZ, PAM4, coherent optics) directly impacts achievable data rates.
4. Multiplexing: DWDM allows multiple channels on a single fiber, dramatically increasing total throughput. In practical terms, a single-mode fiber does not have a fixed "megabit" limit; its capacity depends on the combination of distance, wavelength, and equipment. For example, a single fiber can carry 100 Gbps over 10 km, or multiple DWDM channels can push total throughput into terabits per second for backbone networks . This makes single-mode fiber the preferred choice for long-haul telecommunications, data center interconnects, and high-speed internet backbones.