effective refractive index

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

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

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

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

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.