A comprehensive guide on stepped index fiber optic

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Fiber optic cables differ in types, depending on their applications. Based on the refractive index, there are two types of fiber optic. One is step-index fiber optic, and the other is grade index fiber optic. Both have distinguishing features and work differently. This article will detail what step-index fibers are, how they operate and their applications. Go through and keep read this article to know about stepped index fiber optic.

What is step-index fiber optic?

A step-index fiber optic is the one that is characterized by the uniform refractive index inside the main core. The core-cladding interface experience a strident decrease in refractive index. The reduction in results in lower refractive index cladding. The light rays inside the step-index fiber propagate in a zig-zag manner. The fiber allows the rays to pass through it in a meridional way. Every single beam that moves along the fiber passes through the axis of the fiber. Moreover, the bandwidth of a step-index fiber cable is comparatively lower.

Types of step-index fiber:

Further exploring the term, a step-index fiber cable consists of two main types. One is mono-mode, and the other is multi-mode fiber. A brief breakdown of these two types is given in the lines to come.

1. Mono-mode step-index fiber:

·         A single-mode or mono mode step-index fiber is the one that experiences lower signal distortion. Due to the single mode, it is effective when compared with the multi-mode fiber.

  • The bandwidth for single-mode step-index fiber is more than 100 MHz.
  • There are no chances of intermodal dispersion since only one mode is transmitted.
  • The diameter of mono-mode fiber ranges between 2 microns to 10 microns.
  • It has a greater capacity to carry information across different mediums.
  • Single-mode fiber is more expensive since it requires a LASER diode as a directional source.

2. Multi-mode step-index fiber:

  • Multi-mode step-index fiber is the one that experiences a higher signal distortion. The sole reason for this signal distortion is high-angle rays.
  • When compared with single-mode fiber, the bandwidth of multi-mode fiber is lower that is 50 MHz.
  • It allows the propagation of a finite number of rays to pass through it. Unlikely, it will enable guided modes along the channel.
  • Since numerous modes enter it with different velocities, there are higher chances of dispersions.
  • Unlike the mono-mode step-index fiber, the capacity to carry information is lower due to increased dispersion.
  • LED can be used as a light source, hence making it affordable.

Step-index Profile:

In step-index fiber, the profiles are in the shape of steps. When compared with the index profile of graded-index fiber, they are in the form of a parabolic curve. Uniform refractive index is the point that mainly characterizes the index profile of the step-index. Fiber optic UAE companies mostly use this type of cable for short-distance communication since they have lower bandwidth. The refractive index (RI) is constant inside the core and is higher than inside the cladding. The simplest index profile is rectangular.

Signal Distortion in step-index fiber:

When it comes to signal distortion, the concepts vary. In the case of single-mode step-index fiber, the signal distortion is almost zero. In the case of multi-mode, the signal distortion is relatively higher. The reason is that high-angle rays enter the multi-mode fiber, causing the distortion.

How the light rays propagate through it?

The light rays inside a step-index fiber propagate in a zig-zag manner. Every single stream of light that moves along the fiber passes through the axis of it. On the other hand, rays propagate through the grade-index fiber in skew rays or helical rays. The rays in the graded-index do not pass through the axis of the fiber.

What is modal dispersion in step-index fiber?

Since the power source of fiber optic is light, there is a greater chance of modal dispersion. The phenomenon of scattering occurs when several light rays travel along with the fiber. They spread out and cause dispersion. This phenomenon is mostly found in multi-mode fiber, reducing their bandwidth. The dispersion also causes the modes to overlap each other, causing Inter-symbol Interference (ISI).

Applications of step-index fiber:

As discussed, the modal dispersion is high in multi-mode step-index fibers. Because of one mode in mono-mode cable, the chances of dispersion and signal distortion are relatively lower. Based on these characteristics, both of these types of fiber optics are used in different situations. Both work effectively in their respective areas.

·         Multi-mode fiber is used for short-distance communication systems (within a few kilometers). These cables are also used in communication systems where the speed is low (8MBPS or less).

·         Mono-mode fiber, due to its efficiency, is used in long-distance communication systems. The transmission distance does not affect the performance of the cable due to less dispersion. Fiber optic UAE companies use it for high-speed networking and communication systems.

Why hire professional experts to install these cables?

The installation of fiber optic cables requires some technical skills and knowledge. Without the assistance of these experts, the process could be difficult. Businesses and households need to take these professional companies on board for the successful installation of these cables.