Postdoctoral position at the Langevin Institute

Wavefront shaping and study of light propagation in disordered multimode fibers

We are recruiting a postdoc for 1+ year(s) to work on the study of light propagation in multimode fibers for telecommunication applications using wavefront shaping. Join un in Paris!

See our most recent publication: [Learning and avoiding disorder in multimode fibers, arxiv, 2020]

Contact: Sébastien Popoff - sebastien.popoff(at)espci.fr

More information here.

Making useless (but beautiful) gifs with fiber modes

Social media like (too) short content like pictures or quotes, but above all, people love gifs (probably way too much). Publish a link to a few pages long post you wrote about a paper, a physical concept, or a piece of code, and a few people will like your tweet/post. Publish a gif, and the number of people you will reach will increase dramatically. Is it a good thing? Well, that depends on what you do with it. I try to use gifs to draw attention to more in-depth content that I hope some people will read. Let's make one together.

DMD diffraction tool

I presented in this tutorial the diffraction effects occurring in a DMD setup. It corresponds to a blazed grating effect and depends on the wavelength \(\lambda\), the pixel pitch \(d\), the incident angle \(\alpha\), and the angle of the micro-mirrors \(\theta\). Here is a simple app (see source code on Github) to calculate the criterion for optimal diffraction efficiency and the aspect of the diffraction pattern in the far-field when illuminating the DMD with a plane wave of incident angle \(\alpha\) with respect to the normal of the surface.

How to generate macropixel patterns for SLMs/DMDs with the Layout module

In many wavefront shaping experiments, such as for optimization experiments, like the seminal work by I. Vellkoop and A. Mosk, or for measuring the transmission matrix, one needs to control the amplitude and/or the phase of the field on a given number of macropixels (i.e. groups of pixels). Using DMDs, amplitude, and phase modulation can be achieved using the Lee hologram method and then sending the binary images to the device using the for ALP4lib in Python for Vialux DMDs. I released here a module written by M. W. Matthès and myself to easily and efficiently generate such patterns. The code can be found on my Github account here as well as an amplitude and phase modulation example: layout_amplitude_phase_modulation.ipynb.