We've already introduced you to the history of optical communications, but... what is fiber optics and how does it work? Fiber optics is a light waveguide, a thin and flexible cable.
Light has a dual nature, meaning it behaves as both a wave and a particle; within its wave behavior, it has certain characteristics such as frequency, amplitude, and wavelength. Wavelength and frequency are inversely proportional and allow us to classify light in an electromagnetic spectrum, which is shown in Figure 1. On the right side of this spectrum are the lower frequency and therefore longer wavelength energy classes. Fiber optics works in the infrared (IR) and visible light spectrum. Therefore, the operating wavelength of the fiber ranges from 850 nm to 1550 nm.
Figure 1. Preform
Optical fiber is composed of:
Core: Made of plastic or glass (silicon and germanium oxide), this is the medium through which light is guided.
Cladding: Made of plastic or glass, it is responsible for "trapping" light in the core through total internal reflection.
Coating: A plastic cover that protects the core and cladding from moisture and physical damage.
Figure 2. Fiber drawing
The physical phenomena of refraction and reflection are central to how fiber optics work. When a light beam strikes a boundary surface between two different transparent media, in this case, the core and cladding; part of the light is reflected, remaining in the first medium, as shown in Figure 3, and another part of the light is refracted, penetrating the second medium as shown in Figure 4.
Figure 3. Diameter inspection
Figure 4. Fiber with acrylate
To ensure that light is guided correctly, the core must have a higher refractive index than the cladding. The refractive index tells us how much the speed of light is reduced in the medium it strikes; air, water, quartz, diamonds, and glass each have a different index. Additionally, the angle at which the light strikes is important, as this will determine whether total reflection occurs or not. If total reflection is not achieved, the cladding will not be able to "trap" the light, meaning it will "escape" and we will experience loss of the information being transmitted.
Figure 5. Cables
Figure 5 shows an example of total internal reflection, where beam "a" achieves it without problem, and thus the light is guided correctly through the core. On the other hand, beam "b" does not have the appropriate angle of incidence and does not achieve total internal reflection, so the light "escapes."
Additionally, if the fiber suffers bends, cuts, or has dirt, total internal reflection will not be possible either, and we will lose information or experience service interruption. It is important to perform continuity tests on the network, clean connectors, and perform fiber splices with the necessary equipment and tools.
Remember that at Icoptiks, you can find all these tools, cables, customize your jumpers and pigtails, as well as cleaning supplies and everything necessary for network maintenance.
