Focusing Light through Random Photonic Media by Binary Amplitude Modulation

TL;DR

This paper introduces a binary amplitude modulation technique for focusing light through random photonic media, achieving significant intensity enhancement and demonstrating high-speed wavefront shaping with MEMS devices.

Contribution

It presents a novel binary amplitude modulation method for wavefront shaping, enabling efficient focusing through complex media with high-speed MEMS-based devices.

Findings

Intensity at focus increased by 75 times

Effective focusing demonstrated with amplitude-only SLMs

High-speed wavefront shaping enabled by MEMS devices

Abstract

We study the focusing of light through random photonic materials using wavefront shaping. We explore a novel approach namely binary amplitude modulation. To this end, the light incident to a random photonic medium is spatially divided into a number of segments. We identify the segments that give rise to fields that are out of phase with the total field at the intended focus and assign these a zero amplitude, whereas the remaining segments maintain their original amplitude. Using 812 independently controlled segments of light, we find the intensity at the target to be 75 +/- 6 times enhanced over the average intensity behind the sample. We experimentally demonstrate focusing of light through random photonic media using both an amplitude only mode liquid crystal spatial light modulator and a MEMS-based spatial light modulator. Our use of Micro Electro-Mechanical System (MEMS)-based digital micromirror devices for the control of the incident light field opens an avenue to high speed implementations of wavefront shaping.