Spatiotemporal control of light

Joel A. Carpenter
May 2021

This tutorial investigates various techniques for spatial and/or temporal optical beam manipulation.

Learning and Avoiding Disorder in Multimode Fibers

Sébastien M. Popoff
July 2021

In this work, we demonstrate the existence of a set of spatial channels in multimode fibers that are robust to strong local perturbations. We show that, even for a high level of disorder, light propagation can be characterized by just a few key properties.

Related article: doi.org/10.1103/PhysRevX.11.021060

Time reversed optical waves by arbitrary vector spatiotemporal field generation

Mickael Mounaix, Nicolas K. Fontaine, David T. Neilson, Roland Ryf, Haoshuo Chen, Juan Carlos Alvarado-Zacarias and Joel Carpenter

This video published on J. Carpenter Youtube Channel explained the details of the experiment of this paper [Mounaix et al., arxiv, 1909.07003, (2019)]. The authors use spatial and spectral shaping with a spatial light modulator to achieve spatio-temporal focusing of light by time-reversal through a multimode fiber.

Wavefront Shaping in Complex Media for Linear Analog Computation

Sebastien M. Popoff

PR'19: Photorefractive Photonics and beyond (Gerardmer, France), June 21 2019

Abstract: Performing linear operations using optical devices is a crucial building block in many fields ranging from telecommunications to optical analog 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. 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 analog 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 causes the complex medium to act as a desired complex-valued linear operator on the optical field.