Fiber Optic Cables: Definition, How It Works, and Its Structure

What Are Fiber Optic Cables

Fiber optics is a technology that transmits information in the form of light signals through very thin and transparent optical fibers. These optical fibers consist of a small core surrounded by a protective layer known as cladding. Typically, these fibers are made of glass or specialized plastic with a high refractive index, which allows light to be trapped and propagate through the fiber.

How Fiber Optic Technology Works

The operation of optical fiber relies on a principle of physics known as “total internal reflection.” When light enters an optical fiber at a specific angle, it reflects within the fiber at the same or a smaller angle, allowing the light to continue moving forward with minimal energy loss.

The data signal is encoded as light pulses or variations in light intensity, which are then transmitted through the optical fiber. This light can travel at high speeds and carry substantial amounts of data, making optical fiber ideal for long-distance telecommunications, including telephone networks, the internet, cable television, and computer networks.

Structure of Fiber Optic Cables

Image of a fiber optic cable

A typical fiber optic cable consists of three main layers: Core, Cladding, and Coating.

• Core: The core is the innermost part of a fiber optic cable, where light propagates and reflects. It is often made of special glass or plastic with a high refractive index. In single-mode cables, the core has a very small diameter, while in multi-mode cables, it has a larger diameter. The refractive index of the core is greater than that of the cladding, ensuring that light remains reflected within the core, thus minimizing data signal loss during transmission.

• Cladding: The cladding is the middle layer of the fiber optic cable that surrounds the core. Its primary function is to reflect light back into the core using the principle of total internal reflection, ensuring that light remains concentrated in the core and does not scatter. The cladding has a different refractive index than the core.

• Coating: The coating is the outer layer that protects the core and cladding from physical damage and environmental factors. This protective layer is made from durable materials that resist pressure, moisture, and mechanical damage. It is often composed of plastic or Kevlar fiber, providing additional strength.

Functions of Optical Fiber

Fiber optic cables serve various functions across multiple industries, including:

• Telecommunications: The primary function of fiber optic cables is to act as a transmission medium for telecommunications. They are used in telephone networks, internet connections, cable television, and other data communication networks, enabling the transmission of large amounts of data at high speeds for efficient long-distance communication.

• Computer Networks: Fiber optic cables connect network devices such as switches, routers, and servers, facilitating high-speed and reliable data transmission.

• Broadcasting Industry: In broadcasting, fiber optics transmit audio, video, and data signals between production centers and television or radio stations. They provide high quality and reliability, allowing for high-resolution (HD) and ultra-high-definition (UHD) broadcasting.

• Sensing Applications: Optical fibers are utilized in various sensing applications, including pressure, temperature, and speed sensors. They act as sensitive elements in these sensors, with changes in light within the fiber used to detect and measure physical parameters.

• Lighting: Fiber optics are employed in decorative and architectural lighting. Optical fibers, known as beam optical fibers, deliver light from a central source to illuminate specific areas, such as gardens or buildings, creating interesting light effects and design flexibility.

• Medical Applications: In the medical field, fiber optics are used for procedures such as endoscopy and minimally invasive surgery. Flexible optical fibers transmit light into a patient’s body, allowing doctors to visualize and perform medical procedures with high accuracy.

In addition to these applications, optical fibers are also used in security, industrial control systems, measurements, oil and gas drilling, and the manufacture of sensors and other optical devices. The functions and applications of fiber optics cables continue to evolve with technological advancements and the growing demand for fast and reliable data transmission.

Advantages and Disadvantages of Fiber Optic Cables

Advantages:

• High Speed: Fiber optic cables can transmit data at extremely high speeds, with large bandwidth capacity, allowing for gigabit or terabit speeds per second. This speed facilitates fast and responsive data transfer in telecommunications and computer networks.

• High Capacity: Fiber optics have a significantly greater capacity than conventional copper cables. A single optical fiber can accommodate multiple communication channels simultaneously, enabling denser data transmission and reducing the need for extensive physical infrastructure.

• Long Transmission Distance: Fiber optics excel in long-distance transmission capabilities. Light signals in optical fibers experience less energy loss compared to electrical signals in copper cables, allowing signals to be transmitted over thousands of kilometers without quality or speed degradation. This makes them ideal for long-distance telecommunications networks, including undersea routes.

Disadvantages:

• High Initial Installation Costs: The installation costs for fiber optic cables are higher than those for conventional copper cables. Fiber optics require specialized equipment and technical expertise for installation and splicing, leading to increased initial costs, especially for large-scale installations.

• Susceptibility to Mechanical Damage: While fiber optics are resistant to pressure and pulling, they can be damaged if bent or pulled excessively. Construction work or accidents, such as unauthorized excavation, can lead to damage, resulting in data transmission failures and additional repair costs.

• Difficult Maintenance: Repairing damaged optical fibers typically requires specialized technical expertise. The splicing and testing processes necessitate special equipment and training, which can prolong repair times and increase maintenance costs.

Types of Fiber Optic Cables

There are several types of optical fibers commonly used in various applications:

• Single-mode (SM) Optical Fiber: Designed to transmit light in a single mode or path, with a very small core diameter (around 9 microns). This type is ideal for long-distance and high-speed signal transmission, such as in telecommunications networks.

• Multi-mode (MM) Optical Fiber: Designed to transmit light in multiple modes or paths, with a larger core diameter (ranging from 50 to 62.5 microns). Multi-mode fibers are used for short to medium distances, such as in Local Area Networks (LANs) and broadcasting systems.

• Step-index Optical Fiber: Characterized by a sharp refractive index difference between the core and cladding, allowing light to propagate by reflecting at the boundary. This type is suitable for short to medium distances and can be used for both single-mode and multi-mode applications.

• Graded-index Optical Fiber: Features a gradually varying refractive index from the center of the core to the cladding, resulting in smoother light propagation and reduced signal distortion. This type is typically used for short to medium distances in data communications.

• Plastic Optical Fiber (POF): Utilizes optical fibers made of special plastic instead of glass. POF has a larger core and uses infrared light as a source. It is commonly used in short-range applications, such as local networks, automotive systems, and decorative lighting.

Additionally, there are variations and modifications of optical fibers, such as Polarization-Maintaining Fiber (PMF), which maintains the polarization of light, Double-Clad Fiber for laser applications, and Hollow-Core Fiber, which transmits light through air or gas. Each type of optical fiber has unique characteristics and applications tailored to specific needs

Source :

https://www.techtarget.com/searchnetworking/definition/fiber-optics-optical-fiber

Author: Hassan Rizky Putra S | Editor : Meilina Eka Ayuningtyas