Few mode fiber

[Abeer yehia]

Hello,
i need help please .
I am working on project and need to use few mode fiber and cannot get the s-parameters file of it .

[Steve Dods]

OptiFiber does not calculate S parameters, it calculates modes and modal fields. Modes are orthogonal, so off-diagonal S matrix parameters will all be zero in this space. The diagonal elements of the S matrix will have unit value. They are phases that can be found from the modal index of each mode and the length of the fibre.

[Abeer yehia]

Thanks,but i didn’t understand well,i am using optiSystem so i wanna add s-parameter file of few mode fiber because i did’t find it .
another point, how can use multi mode fiber to act like few mode fiber by controlling the number of modes, what i will need to do that?
note , i need to use 3 mode only of multi mode fiber.

[Steve Dods]

S parameters for a straight length of fibre are only phases. This is because in each mode during propagation there is only delay, no loss and no coupling. The phase delay in each mode is the modal index times the length of the fibre times wavenumber. OptiFiber calculates modal index of each mode, so the S parameters are available from OptiFiber simulations.

The number of modes is determined by the fibre design and the wavelength. Nothing else. a few experiments with OptiFiber will show you that.

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