optical-field-transfer-matrix

Transfer-matrix method to calculate reflectance, transmittance and the electric field strength across an optical multilayer. For a thorough derivation of the method see, for instance: C. C. Katsidis, D. I. Siapkas. Applied Optics, 41, 3978 (2002), https://doi.org/10.1364/AO.41.003978.

Installation

$ git clone https://github.com/andibarg/optical-field-transfer-matrix.git
$ cd optical-field-transfer-matrix

This repository includes implementations both in Matlab (.m files) and in Python (.py file).

Usage (Matlab)

The function 'tmm.m' takes as inputs the wavelength, layer refractive indices n_i and layer widths w_i. It returns the amplitude reflection coefficient r and the transmission coefficient t, as well as arrays to plot the electric field strength E vs position x.

As an example, the script 'example_dbr.m' calculates the field in a lossless dielectric mirror on a glass substrate, where the coating materials are magnesium fluoride (n_MgF2 = 1.38) and zinc sulfide (n_ZnS = 2.32). The following figure shows the normalized electric field strength across 8 alternating layers, each with a thickness of n_i w_i = λ/4, where λ = 1 μm is the wavelength.

For the same mirror the following figure shows the reflectance as a function of wavelengths.