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Showing posts with the label Optical Fibre

### Attenuation of optical signal in optical fibre

Attenuation in Optical Fibre: The difference in the power of the input optical signals and output optical output signals in optical fibre is known as attenuation in the optical fibre. It is measured in decibels per kilometer $(\frac{dB}{Km})$ and caused by the absorption and scattering of the optical signal in optical fibre. The optical signal strength is reduced when the signal travels in optical fibre over a long distance. The expression for the attenuation of optical signal in optical fibre: $\alpha = - \frac{10}{x(Km)} log \left[ \frac{P_{x}}{P_{\circ}} \right]$ Where $P_{x} \rightarrow$ Power of optical signal at a position $x$ from origin $P_{\circ} \rightarrow$ Power of optical signal at origin The Losses in optical fibre are wavelength-dependent and the attenuation factor depends on the fibre material and manufacturing tolerance. A.) Absorption of optical signal in optical fibre: The absorption of optical signals in optical fibre depends on the a

### Principle of optical fibre communication

Optical Fibre Communication: Optical fibre communication is a method of communication in which an optical wave passes through optical fibre by the total internal reflection principle. This optical signal consists of the electrical signal (Also known as information) and the laser beam i.e. a carrier wave. The optical fibre is used as a waveguide or transmission medium in optical fibre communication. Principle of optical fibre communication: In the optical fibre communication principle, the information (such as voice) is first converted into an electrical signal. Then it is modulated onto the laser beam (Also known as a carrier wave). In the modulation process, The electrical signal is superimposed onto the laser beam and the frequency of laser light changes with the frequency of the electrical signal. The optical fibre communication uses the pulse code modulation (PCM) for transmitting the optical signal. Now modulated optical signal passes through the optical fibre or waveguide