Why is it called coaxial optical cable

A coaxial optical cable is a hybrid transmission medium that combines the structural principles of coaxial cables with optical fiber technology to transmit light signals efficiently.

Overview

A coaxial optical cable merges the concentric layered design of a coaxial cable with the light-transmitting properties of optical fiber. Traditional coaxial cables consist of a central conductor, a dielectric insulator, a metallic shield, and an outer protective layer, designed to carry high-frequency electrical signals with minimal interference . In a coaxial optical cable, the central conductor is replaced or supplemented by an optical fiber core, which transmits data as light rather than electrical signals, while the surrounding layers provide mechanical protection and shielding from physical stress or electromagnetic interference.

Structure

1. Optical Core: The central fiber, usually made of glass or plastic, carries light signals.
2. Cladding Layer: Surrounds the core and has a lower refractive index to reflect light back into the core, ensuring efficient transmission .
3. Dielectric or Insulating Layer: Maintains spacing and protects the fiber from mechanical stress.
4. Metallic Shield (Optional): Provides additional protection against electromagnetic interference, similar to traditional coaxial cables .
5. Outer Jacket: A protective polymer layer that shields the cable from environmental damage.

Advantages

• High Bandwidth: Optical transmission allows for much higher data rates than electrical coaxial cables, supporting multiple channels simultaneously .
• Reduced Signal Loss: Light signals experience lower attenuation over long distances compared to electrical signals in standard coaxial cables .
• Mechanical Protection: The coaxial-like layers provide durability and resistance to bending or crushing, which is beneficial in harsh installation environments.

Applications

Coaxial optical cables are used in scenarios where high-speed data transmission is required along with robust physical protection, such as:

• Cable television and broadband internet backbones
• Telecommunications networks in urban or industrial areas
• Hybrid systems where optical fiber is integrated into existing coaxial infrastructure

Summary

While standard coaxial cables transmit electrical signals and optical fibers transmit light, a coaxial optical cable combines these technologies, offering the high bandwidth and low attenuation of optical fibers with the protective, layered structure of coaxial cables. This makes it suitable for high-performance, durable communication networks .