Created by admin on 15/09/2020


Real-time shaping of entangled photons by classical control and feedback

[O. Lib, G. Hasson and Y. Bromberg, Sci. Adv. 6 (2020)]

Wavefront shaping offers the possibility to compensate for the effect of propagation through heterogeneous media. However, when using a single or a few photons, the feedback signal is typically too weak to allow real-time wavefront shaping applications, which limits applications for quantum communications using entangled photons. In this paper from the team of Yaron Bromberg at the Hebrew University of Jerusalem, the authors overcome this challenge by using as feedback the classical signal of the pump that follows the same path as the entangled photon. It allows adapting in real-time the pump wavefront to compensate for the aberrations/scattering introduced by a heterogeneous dynamic sample.

See full post
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.

See full post
Created by sebastien.popoff on 18/08/2020


Taking advantage of imperfections to focus light in photonic crystals inside the stop gap

[R. Uppu et al., arxiv, 2007.11104v1 (2020)]

Photonic crystals have the ability to forbid the entrance of light for certain ranges of frequencies, that is even the usual reason why we build them. Within the spatial frequency range for which the stop band of a given photonic crystal exists, modulation of the input wavefront should not dramatically modify the penetration of light, which exhibits an exponential decay. In this paper, R. Uppu and collaborators from the University of Twente demonstrate that it is indeed possible to drastically change the penetration properties of light inside a photonic crystal by optimizing the wavefront taking advantage of unavoidable sources of disorder. They experimentally show the focusing of light inside such crystal beyond the expected maximal penetration length - the Bragg length.

See full post
Created by sebastien.popoff on 12/06/2020

Talks Wavefront shaping

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.

See full post