Why can't the optical cable be twisted or bent

Optical fibers are the backbone of modern telecommunication and data transmission networks. They transmit data over long distances by using light signals, and are known for their high bandwidth and low signal attenuation. However, optical fibers are also fragile, and care must be taken to avoid bending or twisting them. In this article, we will discuss the reasons why optical cables should not be twisted or bent, and the consequences of doing so.

Optical fibers are made of glass or plastic, and are designed to transmit light signals through their core. The core is surrounded by a cladding layer, which has a lower refractive index than the core. This creates a boundary that reflects the light signals back into the core, allowing them to travel long distances without significant loss of signal strength.

When an optical cable is bent or twisted, the fibers inside the cable can be damaged. This damage can take several forms, including micro-bending, macro-bending, and stress-induced attenuation.

Micro-bending occurs when the fiber is bent at a small radius, typically less than a few millimeters. This can occur during installation, when the cable is being pulled through tight spaces or around corners. Micro-bending can cause small deformations in the fiber's cladding layer, which can scatter the light signals and cause signal attenuation.

Macro-bending occurs when the fiber is bent at a larger radius, typically several centimeters or more. This can occur when the cable is coiled or bent around a large object. Macro-bending can cause the fiber's cladding layer to deform even more, which can result in significant signal attenuation.

Stress-induced attenuation occurs when the fiber is subjected to tensile or compressive stress. This can occur when the cable is pulled too tight or when it is stepped on or crushed. Stress-induced attenuation can cause the fiber's core to deform, which can lead to significant signal loss.

The consequences of bending or twisting an optical cable can be severe. The most obvious consequence is signal loss. The light signals can be scattered or absorbed by the damaged fiber, reducing the strength of the signal and potentially causing data errors or transmission failure. In addition, the damage to the fiber can be cumulative, meaning that the signal attenuation will increase over time.

Another consequence of bending or twisting an optical cable is increased cable loss. When the cable is bent or twisted, the fibers can move inside the cable, which can create small gaps or spaces between the fibers. These gaps can cause light signals to leak out of the cable, reducing the overall signal strength and potentially causing interference with other devices or cables.

To avoid damaging optical fibers, it is important to handle optical cables carefully and follow best practices for installation and maintenance. Some common best practices include:

Avoid sharp bends or twists in the cable. The minimum bend radius for most optical cables is typically several times the diameter of the cable. Check the manufacturer's specifications for specific guidance.

Use cable ties or clamps to secure the cable and prevent it from moving or vibrating.

Use protective conduit or tubing to shield the cable from sharp edges or other hazards.

Follow recommended installation procedures, such as using proper tools and techniques for cable pulling and termination.

Avoid exposing the cable to excessive tension or compression. Use proper cable supports and avoid stepping on or crushing the cable.

In summary, optical fibers are fragile and must be handled carefully to avoid damage. Bending or twisting an optical cable can cause signal loss, cable loss, and potential data errors or transmission failure. By following best practices for cable handling and installation, it is possible to maintain the integrity and reliability of optical cables and ensure optimal performance over their lifetime.