Second-harmonic focusing by nonlinear turbid medium via feedback-based wavefront shaping

TL;DR

This paper demonstrates a method to focus second-harmonic waves in nonlinear turbid media using feedback-based wavefront shaping, enabling enhanced control over nonlinear light scattering and potential advanced imaging applications.

Contribution

It introduces a novel technique combining nonlinear optics and wavefront shaping to control second-harmonic scattering in turbid media, expanding the capabilities of optical focusing.

Findings

Successful focusing of second-harmonic waves in turbid media

Controlled manipulation of linear and nonlinear scattering signals

Potential for nonlinear transmission and multi-frequency imaging

Abstract

Scattering has usually be considered as detrimental for optical focusing or imaging. Recently, more and more research has shown that strongly scattering materials can be utilized to focus coherent light by controlling or shaping the incident light. Here, purposeful focusing of second-harmonic waves, which are generated and scattered from nonlinear turbid media via feedback-based wavefront shaping is presented. This work shows a flexible manipulation of both disordered linear and nonlinear scattering signals, indicating more controllable degrees of freedom for the description of turbid media. This technique also provides a possible way to an efficient transmission of nonlinear signal at a desired location in the form of a focal point or other patterns. With the combination of random nonlinear optics and wavefront shaping methods, more interesting applications are expected in the future, such as nonlinear transmission matrix, multi-frequency imaging and phase-matching-free nonlinear optics.