Real-time wavefront-shaping through scattering media by all optical feedback

TL;DR

This paper introduces a rapid all-optical feedback method for wavefront-shaping that enables focusing through scattering media at sub-microsecond timescales, surpassing traditional SLM-based techniques in speed.

Contribution

The authors demonstrate a novel all-optical feedback approach using a multimode laser cavity to achieve ultra-fast wavefront-shaping without electronic feedback or spatial light modulators.

Findings

Achieved wavefront-shaping at sub-microsecond timescales

Enabled focusing through biological tissues and scattering media

Surpassed traditional methods by over five orders of magnitude in speed

Abstract

Focusing light through dynamically varying heterogeneous media is a sought-after goal with important applications ranging from free-space communication to nano-surgery. The underlying challenge is to control the optical wavefront with a large number of degrees-of-freedom (DOF) at timescales shorter than the medium dynamics. Recently, many advancements have been reported following the demonstration of focusing through turbid samples by wavefront-shaping, using spatial light modulators (SLMs) having >1000 DOF. Unfortunately, SLM-based wavefront-shaping requires feedback from a detector/camera and is limited to slowly-varying samples. Here, we demonstrate a novel approach for wavefront-shaping using all-optical feedback. We show that the complex wavefront required to focus through highly scattering samples, including thin biological tissues, can be generated at sub-microsecond timescales by the process of field self-organization inside a multimode laser cavity, without requiring electronic feedback or SLMs. This wavefront-shaping mechanism is more than five orders of magnitude faster than state-of-the-art, reaching the timescales required in many applications.