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I shine laser line in front of one side of multimode optical fibre.Light coming out of other side is projected into wall.Whether the intensity pattern seen on wall is same as the mode of propagation of light pattern drawn on text books?

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    $\begingroup$ Welcome! Could you clarify the last sentence? $\endgroup$ – Volker Siegel Aug 4 '14 at 23:43
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I am assuming that you are asking how to reproduce an interference pattern: The total electric field distribution anywhere in a multimode fiber is a superposition of contributions from the different modes. The intensity profile depends not only on the optical powers in all the modes, but also on the relative phases, and there can be constructive or destructive interference of different modes at particular locations in the fiber. Both the powers and optical phases are initially determined by the launching conditions, and the relative phases (and thus the interference conditions) evolve further due to the mode-dependent propagation constants. Therefore, the more or less complicated intensity pattern changes all the time, typically with significant changes occurring within a propagation length of well below 1 mm. Also, the relative phases changes with any modifications of the launching conditions, bending or stretching of the fiber, changes of the wavelength or temperature, etc.

PhotonicsEncyclopedia:Multimode-Fibers

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