Created by sebastien.popoff on 01/09/2020

## Spatio-temporal shaping of light through a scattering medium

[A. Boniface et al., arxiv, 2007.09050 (2020)]

Controlling the spatial and temporal properties of a short pulse is already difficult in free space, and require a well-calibrated and specific setup. When the pulse propagates through a scattering medium, its temporal and spatial properties are randomized, leading to a spatio-temporal speckle. However, the effect of the medium can be described by means of the multi-spectral transmission matrix. In this paper, A. Boniface and his colleagues show that by measuring previously this matrix, and by only controlling the spatial input field using a spatial light modulator, they can modulate at will the spatio-temporal properties of the point spread function of a pulse traveling through a complex medium.

Created by sebastien.popoff on 25/08/2020

## Using prior information for speeding up the measurement of fiber transmission matrices

[S. Li et al., arxiv, 2007.15891, (2020)]

Due to disorder and dispersion, knowing the transmission matrix of a multimode fiber is usually required to reconstruct an input image for endoscopic applications. In the general case, its characterization for a fiber allowing $$N$$ guided modes requires at least $$N$$ complex measurements. However, we usually have additional information, the most common one being that the matrix is never totally random, and usually sparse, when expressed in the mode basis. In this study, the authors use such prior information to reduce drastically the number of measurements for the transmission matrix estimation using the framework of compressed sensing. They demonstrate the validity of such an approach for endoscopic imaging through multimode fibers.

Created by sebastien.popoff on 11/08/2020

## 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!

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