... Also another area of physics that is closely related to the laser is total internal reflection (TIR). This is where the laser is fired down the optical tube and is bounced along its length. This will be discussed later. The reason they use lasers is because laser are light that is of a very small and consistent wavelength. Also they are always in phase and move in parallel lines. Also it is quite easy to produces a very bright light therefore a very strong signal with lasers this covered in the next section. This therefore makes for a good source of a signal. The reason that TIR is needed is because it is by nature the only way possible for the light signal to get to the other end of the cable. There are no real direct ethical or social problems with what is done at Alcatel although after visiting the ...

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