IF-DDA is a numerical tool for solving the electromagnetic scattering problem in three dimensions. IF-DDA is based on the DDA (discrete dipole approximation) which is a volume-integral equation method. The DDA (also referred to as the coupled dipole method) was originally proposed by by Purcell and Pennypacker where the object under study is discretized into a set of small subunits and the field at each subunit position is computed through a self consistent equation. Then the diffracted field can be computed easily. This method can be used to arbitrarily shaped, inhomogeneous, anisotropic particles. The radiation condition is automatically satisfied, because the Green's function satisfies the radiation condition. The computation is confined to the volume of the scatterer, hence this method does not need any PML (perfect matching layer). IF-DDA has a very friendly guide user interface where many particles (cuboid, sphere, ellipsoid, many spheres,...), beams (plane wave, Gaussian wave, multiple plane waves,...) are accessible with a drop-down menu. The studies are selected with the mouse:

• Cross section
• Poynting vector
• Microscopy (bright field, dark field, confocal, schieren,...
• Optical force
• Optical torque
• Near field

IF-DDAM is as IFDDA but the object can be placed in a multilayer that may support guided waves or plasmon. We have also strongly developed IFDDA to enable to study a wide range of microscope types. For details on the different possibilities of the DDA, please refer to:

1. P. C. Chaumet
   The Discrete Dipole Approximation : a review
   Mathematics 10, 3049 (2022).
2. P. C. Chaumet, P. Bon, G. Maire, A. Sentenac and G. Baffou
   Quantitative phase microscopies: accuracy comparison
   Light : Science & Applications 13, 288 (2024).
3. P. C. Chaumet, D. Sentenac, G. Maire, M. Rasedujjaman, T. Zhang and A. Sentenac
   IFDDA, an easy-to-use code for simulating the field scattered by 3D inhomogeneous objects in a stratified medium: tutorial
   J. Opt. Soc. Am. A 38, 1841 (2021).

List of my articles that use the ifdda software.

Examples of the GUI

The figure below shows how the beam and the object are selected. In the "Illumination Properties" section, the power and the waist (or diameter for the laser beam) are fixed, and then you can choose the beam type from the drop-down menu (linear or circular plane wave, Gaussian wave, antenna, multiple plane waves, etc., or an arbitrary beam). Next, in the "Object Properties" section, you can select the object from the drop-down menu (sphere, cuboid, cylinder, ellipsoid, inhomogeneous sphere, concentric spheres, multiple spheres, etc., or an arbitrary object). By clicking "Props" you can set the characteristics of the object (size), and with "epsilon" and "iso", you can choose the values for permittivity and specify whether it is anisotropic. The discretization option determines the number of layers used to represent the object In the part Study you choose the computation asked: in the present case Microscope for Holographic microscope, and optical force and field inside the object.



Then we can use matlab (with UI interface) or the graphical interface of the code (right side of the figure) to see the results.

To get more images you can use this link.

IF-DDA(M) has been developed by

P. C. Chaumet, A. Sentenac, Aix-Marseille University (France).
D. Sentenac, Università di Pisa (Italy).

User Guide.

The reader can find more details on the code with the user guide in English or in French.

	IF-DDA	IF-DDAM
User Guide in English	Userguide	Userguide
User Guide in French	Userguide	Userguide

How to download the code

	IF-DDA	IF-DDAM
Download the tgz file	IF-DDA (Qt5) IF-DDA (Qt6)	IF-DDAM (Qt5)
Download with gitlab	IF-DDA	IF-DDAM

The code use Qt5 for the version 0.x.x et Qt6 for the version 1.x.x

How to install the code

You should uncompressed the file with tar -xvzf cdm-x.x.x.tgz for IF-DDA or tar -xvzf cdmsurf-x.x.x.tgz for IF-DDAM. A readme or install is given in the tar file. Please read it to install the code on linux system. Note that the code can be installed on windows system (it can be tricky to install FFTW on the windows system, see www.fftw.org/install/windows for details.

How to cite the code

-If only the basic functions of the code are used:
P. C. Chaumet, D. Sentenac, G. Maire, M. Rasedujjaman, T. Zhang and A. Sentenac
IFDDA, an easy-to-use code for simulating the field scattered by 3D inhomogeneous objects in a stratified medium: tutorial
J. Opt. Soc. Am. A 38, 1841 (2021).

-If the microscopy is used:
S. Khadir, D. Andren, P. C. Chaumet, S. Monneret, N. Bonod, M. Käll, A. Sentenac and G. Baffou
Full optical characterization of single nanoparticles using quantitative phase imaging
Optica 7, 243 (2020). Supplementary Material.

-If the calculation of the optical forces is used, then:
P. C. Chaumet, A. Rahmani, A. Sentenac and G. W. Bryant
Efficient computation of optical forces with the coupled dipole method.
Phys. Rev. E 72, 046708 (2005).

-If the calculation of optical torque is used:
P. C. Chaumet and C. Billaudeau
Coupled dipole method to compute optical torque: Application to a micropropeller.
J. Appl. Phys. 101, 023106 (2007).

-If the rigorous Gaussian beam is used:
P. C. Chaumet
Fully vectorial highly non paraxial beam close to the waist.
J. Opt. Soc. Am. A 23, 3197 (2006).

Contact

email: patrick.chaumet@fresnel.fr, patrick.chaumet@univ-amu.fr

Licence

Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)
You are free to:

• Share, copy and redistribute the material in any medium or format
• Adapt, remix, transform, and build upon the material
• In addition, you undertake to include citation (see userguide) whenever you present or publish results that are based on it.
• Licensees may copy, distribute, display, and perform the work and make derivative works and remixes based on it only for non-commercial purposes.
• The CNRS makes no warranties of any kind on this software and shall in no event be liable for damages of any kind in connection with the use and exploitation of this technology.

The licensor cannot revoke these freedoms as long as you follow the license terms.