# Wavefront shaping techniques in complex media

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- Category: Highlights
- Published on Monday, 13 May 2019 12:11

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## The Speckle-Correlation Transmission Matrix [highlight]

[K. Lee and Y. Park, Nat. Commun, 7 (2016)]

[Y. Baek, K. Lee and Y. Park, Phys. Rev. Appl., 7 (2016)]

Measuring the optical phase is an ubiquitous challenge in optique. Through a linear scattering medium, one can always links the output optical field to the input one using the transmission matrix. However, one still has to measure the phase of the complex output field. In [K. Lee and Y. Park, Nat. Commun, 7 (2016)] the authors introduce a technique to reconstruct a complex optical field using a thin diffuser. Once the matrix is calibrated, only an intensity measurement is required to reconstruct the amplitude and the phase of the complex optical field.

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- Category: PhD offers
- Published on Wednesday, 08 May 2019 07:56

## [job offer] Multiple PhD positions in optical communications and fiber imaging

### Center for Laser Physics, Atomes and Molecules (PhLAM), Lille, France

Optical communications: *Towards a better understanding of light scattering and mode coupling mechanisms in *few mode* optical fibers* - Link

Optical communications: *Multimodal photonics - dynamic characterization of the transmission channel of a few-mode optical fiber* - Link

Advanced THz photonics: *Beam manipulation with optical-RF antenna arrays at THz frequencies for point-to-point communication applications* - Link

Ultra-miniaturized endoscopes: *Specialty optical fiber for ultraminiaturized biomedical endoscopes - *Link

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- Category: Highlights
- Published on Monday, 15 April 2019 13:50

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## Wavefront shaping in complex media for analog computation [highlight]

[M. W. Matthès et al., Optica, 6 (2019)]

Performing linear operations using optical devices is a crucial building block in many fields ranging from telecommunications to optical analogue computation and machine learning. For many of these applications, key requirements are robustness to fabrication inaccuracies, reconfigurability and scalability. Traditionally, the conformation or the structure of the medium is optimized in order to perform a given desired operation. Since the advent of wavefront shaping, we know that the complexity of a given operation can be shifted toward the engineering of the wavefront, allowing, for example, to use any random medium as a lens.

In [M. W. Matthès et al., Optica, 6 (2019)], we propose to use this approach to use complex optical media such as multimode fibers or scattering media as a computational platform driven by wavefront shaping to perform analogue linear operations. Given a large random transmission matrix representing the light propagation in such a medium, we can extract any desired smaller linear operator by finding suitable input and output projectors. We demonstrate this concept by finding input wavefronts using a Spatial Light Modulator that cause the complex medium to act as a desired complex-valued linear operator on the optical field.

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- Category: Multimode fibers
- Published on Monday, 25 February 2019 16:20

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## [tutorial] pyMMF: Simulating Multimode Fibers in Python

## Part 1: Step Index Benchmark

I recently published a two-part tutorial on how to find the modes of an arbitrary multimode fiber without or with bending. Based on this tutorial, I published a (still experimental) version of a Python module to find the modes of multimode fibers and calculate their transmission matrix: pyMMF. The goal of this module is not to compete with commercial solutions in term of precision but to provide a way to easily simulate realistic fiber systems. To validate the approach, I use step-index multimode fibers as a benchmark test as the dispersion relation is analytically known (see my tutorial here) and for which the Linearly Polarized (LP) mode approximation yields good results. I focus my attention here on the precision of the numerically found propagation constants.

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- Category: Events
- Published on Monday, 18 February 2019 16:47

## Complex Nanophotonics Science Camp 2019

### Aug 11th - Aug 14th 2019

### Cumberland Lodge

### Windsor, United Kingdom

**Organizers: **Jacopo Bertolotti (University of Exeter, UK), Paloma Arroyo Huidobro (Imperial College London, UK), Giorgio Volpe (University College London, UK), Kevin Vynck (LP2N , Bordeaux, France)

## Link: here

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- Category: Events
- Published on Thursday, 14 February 2019 11:22