We should have a group index function sip.n_g(....)
We don't need a separate derivative function. We can just use 2nd order finite difference.
But it's important to check what happens with finite difference when we have 0.1nm spacing vs 5nm spacing in wavelength. We should check if there is a big difference in n_g, due to the spline interpolation to 0.1nm. Best way to do that is to compare the two on the same plot.
We should have a group index function
sip.n_g(....)We don't need a separate derivative function. We can just use 2nd order finite difference.
But it's important to check what happens with finite difference when we have 0.1nm spacing vs 5nm spacing in wavelength. We should check if there is a big difference in
n_g, due to the spline interpolation to 0.1nm. Best way to do that is to compare the two on the same plot.