Thursday, August 4, 2011

Application of total internal reflection

One of the applications of total internal refection is is the optical fibre.
It can be used in fibre-optic communication. Fiber-optic communication is a way of transmitting information from one location to another by sending light through an optical fiber.
Fiber-optic communication (The process):
1. Creating optical signal using a transmitter
2. Relaying the optical signal along the optical fibre
3. Ensuring that the optical signal does not become too weak
4. Receiving the optical signal
5. Converting the optical signal into an electrical signal

Underlying Theory
Total internal reflection
Total internal reflection happens when a ray of light strikes a medium’s surface at an angle larger than the critical angle of the medium. If the refractive index is lower on the other side of the surface, no light can pass through and all the light is reflected. The critical angle is the angle of incidence which the total internal reflection occurs.
Optical fibre
Optical fibre normally consists of a transparent glass core surrounded by a transparent coating with a lower refractive index. Light is kept in the glass core by total internal reflection. This causes the fiber to act as a waveguide.


1. Can be used over greater distances due to the low loss, high bandwidth properties
2. It can be used for 2km without the use of a repeater
3. Their light weight and small in size, which makes them ideal for applications where running copper wires would be impractical
4. Due to the fibres being non-conductive, it can be used where electrical isolation is needed
5. The fibres are do not pose a threat to its surroundings, such as in a chemical plant where a spark could cause an explosion.
6. For security reasons, as it is very hard to tap into a fibre cable to read data signals. 


Although there are many advantages there are a few disadvantages that would effect the installation of these cables these are:
1. It is much more costly than other cables to install
2. It is relatively difficult to install

Application: (Fiber-optic communication - Wikipedia)
Underlying Theory: (Total internal reflection - Wikipedia) (Optical Fiber - Wikipedia)
Advantages and Disadvantages: (Advantages and Disadvantages)
Picture: (Optical fiber cable image)

Done by: Tse Tzang, Christian, JingHeng

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