For Transfer matrix operations -

    import PyTMM.transferMatrix as TMM

    a = TMM.TransferMatrix.layer(n, d, wavelength, theta, TMM.Polarization.s)
    R,T = TMM.solvePropagation(a)

For interfacing with the RefractiveIndex.Info databse-

    from refractiveIndex import *

    catalog = RefractiveIndex(path_to_database)
    si = catalog.getMaterial('main', 'Si', 'Aspnes')

    n = si.getRefractiveIndex(wavelength)