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effective refractive index

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(joined April 2014)
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Hi,

I need to calculate effective refractive index along a fiber taper in order to calculate the localize Brillouin scattering parameters along the fiber taper. Is FDTD the best program to use?

Responses (5):

    • #11249
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      zulfadzli yusoff
      Participant

      Hi,

      I need to calculate effective refractive index along a fiber taper in order to calculate the localize Brillouin scattering parameters along the fiber taper. Is FDTD the best program to use?

    • #11340
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      Lizzie Li
      Participant

      OptiFiber can calculate the effective refractive index of fiber taper. And you can define the taper you want to simulate.

    • #11365
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      saima buzdar
      Participant

      Hi
      Is the Modal index different from the effective refractive index ?
      if yes then what does show the modal index value like :Mode 1 ( 1.35890436, 0.00000283 )

      Thanks

    • #11369
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      Lizzie Li
      Participant

      Yes, mode index is different from the effective refractive index. After defining the fiber, you can get the effective refractive index by calculating modes.

    • #11382
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      saima buzdar
      Participant

      In OptiFDTD after modes calculation we get data like this:

      [ Modes ] [ Modal Index ] [ Polarization ]
      Mode 1 ( 1.35890436, 0.00000283 ) FVect TE
      Mode 2 ( 1.35909016, -0.00000458 ) FVect TM
      i want to know that what does modal index show?
      How Effective refractive index is calculated in FDTD ?

      Thanks

    • #11760
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      Steve Dods
      Participant

      The definition of Modal Index seems to be consistent and well defined. Modal index is the propagation constant of the mode divided by the free-space wavenumber, k ( k = 2 Pi / wavelength ). Since Modal Index is the quotient of two wave numbers it is dimensionless, like refractive index. Effective Index is sometimes used to mean Modal Index, but that is a bad choice of words because Effective Index is a term used for other things too. Effective Index sometimes means a number that will be useful in characterizing a material when a 2D simulation will be used to approximate propagation on a 3D structure. That is why I always use the term Modal Index when referring to a number that represents the propagation constant of a mode. Less confusing/ ambiguous. As for how Modal Index is calculated in OptiFDTD, well, that is a long story. You can find it in Optiwave OptiMode documentation.

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