Intensity-only measurement of partially uncontrollable transmission matrix: demonstration with wave-field shaping in a microwave cavity

TL;DR

This paper introduces a phase retrieval method to identify transmission matrices in complex media with uncontrollable components using intensity-only measurements, demonstrated in microwave cavity wave-field shaping.

Contribution

It presents a novel approach to determine partially uncontrollable transmission matrices solely from intensity data, enabling wave control in challenging environments.

Findings

Successful TM identification with intensity-only data

Effective focusing on single and multiple targets

Application demonstrated in microwave cavity experiments

Abstract

Transmission matrices (TMs) have become a powerful and widely used tool to describe and control wave propagation in complex media. In certain scenarios the TM is partially uncontrollable, complicating its identification and use. In standard optical wavefront shaping experiments, uncontrollable reflections or additional sources may be the cause; in reverberating cavities, uncontrollable reflections off the walls have that effect. Here we employ phase retrieval techniques to identify such a partially uncontrollable system's TM solely based on random intensity-only reference measurements. We demonstrate the feasibility of our method by focusing both on a single target as well as on multiple targets in a microwave cavity, using a phase-binary Spatial-Microwave-Modulator.