Abstract
The memory effect in disordered systems is a key physical phenomenon that has been employed for optical imaging, metrology, and communication through opaque media. Under the conventional memory effect, when the incident beam is tilted slightly, the transmitted pattern tilts in the same direction. However, the “memory” is limited in its angular range and tilt direction. Here, we present a general approach to customize the memory effect by introducing an angular memory operator. Its eigenstates possess perfect correlation for tilt angles and directions that can be arbitrarily chosen separately for the incident and transmitted waves, and can be readily realized with wave front shaping. This work reveals the power of wave front shaping in creating any desired memory for applications of classical and quantum waves in complex systems.
- Received 5 November 2020
- Accepted 11 May 2021
DOI:https://doi.org/10.1103/PhysRevX.11.031010
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
To see through an opaque medium, researchers have begun to focus on harnessing hidden correlations of seemingly random speckles formed by the interference of light scattered through the medium. The most widely used type of correlations is known as the angular memory effect: Tilting the incident wave front of a coherent beam on a diffusive medium tilts the transmitted wave front in the same direction by the same amount. However, its small angular range and the fact that the tilt directions are always the same for input and output light limit practical applications. Here, we propose and experimentally demonstrate a general approach to tailor the angular memory effect at will, in any random scattering medium.
In our method, first we measure the scattering medium’s transmission matrix, a mathematical object that encodes how incident light relates to transmitted light. Then, performing certain transformations on the transmission matrix, we define an “angular memory operator,” a mathematical tool that encodes how to shape the wave front of the incident light to customize the angular memory effect for arbitrarily chosen input and output angles. The input and output angles are determined while defining the operator.
Our work opens the door to customize the memory effect of both classical and quantum waves for imaging, metrology, and communication applications in a diverse set of complex scattering systems.