Multilayers with incoherent propagation

[iliarasskazov]

It would be nice to have an example script for calculating light propagation in stacks with optically thick layers. It looks like you have implemented such a capability [Katsidis 2002], yet the demonstration is not presented.

[bahremsd]

Hi! 👋

We actually included a thick layer example in the README to illustrate the handling of optically thick films, but if you think a more detailed demonstration would be helpful, we can definitely add a more comprehensive example under the examples/ directory.

For instance, the following script demonstrates how light propagation can be simulated through a multilayer stack:

import jax.numpy as jnp
from tmmax.tmm import tmm

# Define multilayer structure and simulation parameters
material_list = ["Air", "Y2O3", "TiO2", "Y2O3", "TiO2", "Y2O3", "TiO2", "SiO2"]
thickness_list = jnp.array([2000e-9, 100e-9, 2000e-9, 100e-9, 2000e-9, 100e-9])
coherency_list = jnp.array([1, 0, 1, 0, 1, 0])
wavelength_arr = jnp.linspace(500e-9, 700e-9, 1000)
angle_of_incidences = jnp.linspace(0, (70 * jnp.pi / 180), 1000)

# s-polarization
R_s, T_s = tmm(
    material_list=material_list,
    thickness_list=thickness_list,
    wavelength_arr=wavelength_arr,
    angle_of_incidences=angle_of_incidences,
    coherency_list=coherency_list,
    polarization='s'
)

# p-polarization
R_p, T_p = tmm(
    material_list=material_list,
    thickness_list=thickness_list,
    wavelength_arr=wavelength_arr,
    angle_of_incidences=angle_of_incidences,
    coherency_list=coherency_list,
    polarization='p'
)

[iliarasskazov]

A separate example in examples/ directory will be much better, especially comparing the spectra where all the layers are treated as coherent, and the spectra where optically thick layers have proper incoherence.

On a side note, I would recommend either to rename the variable coherency_list to incoherency_list, or to switch ones with zeros, because current representation creates an impression that 1 corresponds to a coherent layer as the name of the variable suggests.

[bahremsd]

Sure, we will add an example for this in the examples/ directory.

As you suggested, we have noted the idea of renaming the coherency_list variable. In a future version, together with the refractive index implementation, this change will be included. However, since I am currently the only developer for tmmax, I plan to complete this update in about two months. FYI