Total Internal Reflection in Optical Fibres

Optical fibres are thin, long, and flexible strands of glass or plastic that are used to transmit light signals over long distances. They are widely used in telecommunications, medical equipment, and scientific instruments.

The phenomenon of total internal reflection plays a crucial role in the functioning of optical fibres. Let's understand how it works.

What is Total Internal Reflection?

Total internal reflection is a phenomenon that occurs when a light ray traveling inside a medium strikes the boundary with another medium at an angle greater than the critical angle. In such a case, instead of refracting or bending, the light ray gets reflected back into the same medium.

The critical angle is the angle of incidence at which the refracted angle becomes 90 degrees. If the angle of incidence is greater than the critical angle, then the refracted angle becomes greater than 90 degrees, which is not possible. Hence, the light ray undergoes total internal reflection.

How does Total Internal Reflection work in Optical Fibres?

In an optical fibre, the light signal is transmitted through a core, which is a thin strand of glass or plastic surrounded by cladding. The refractive index of the core is higher than that of the cladding, which causes the light to travel inside the core through total internal reflection.

The light is injected into one end of the fibre by a light source, and it travels through the core by undergoing multiple total internal reflections. As the light travels through the core, it gets attenuated due to absorption, scattering, and other losses.

However, the losses can be minimized by using high-quality materials, proper design, and careful handling of the fibres. In addition, the use of amplifiers and repeaters can boost the signal strength and compensate for the losses.

Advantages of Optical Fibres

Optical fibres offer several advantages over traditional copper wires and other transmission media. Some of the key advantages are:

1. High bandwidth: Optical fibres can transmit data at very high speeds, allowing for faster communication and data transfer.

2. Long-distance transmission: Optical fibres can transmit signals over much longer distances than copper wires, without significant signal degradation.

3. Immunity to electromagnetic interference: Optical fibres are immune to electromagnetic interference, making them ideal for use in environments with high electromagnetic noise.

4. Security: Optical fibres are difficult to tap or intercept, making them more secure than other transmission media.

Conclusion

In conclusion, total internal reflection is a crucial phenomenon that enables the transmission of light signals through optical fibres. By utilizing this phenomenon, optical fibres offer several advantages over other transmission media and have revolutionized the field of telecommunications and data transmission.