Time reversed optical waves by arbitrary vector spatiotemporal field generation

TL;DR

This paper demonstrates the creation of fully arbitrary, time-reversed optical waves by using a novel ultrafast wavefront shaping device capable of controlling all classical degrees of freedom of light.

Contribution

It introduces a new ultrafast wavefront shaper that can generate arbitrary 2D spatial and polarization wavefronts at THz bandwidths, enabling full control of optical fields.

Findings

Achieved generation of time-reversed optical waves with arbitrary amplitude, phase, and polarization.

Device operates at a bandwidth limited rate of 4.4 THz.

Potential to manipulate both linear and nonlinear optical phenomena.

Abstract

Lossless linear wave propagation is symmetric in time, a principle which can be used to create time reversed waves. Such waves are special 'pre-scattered' spatiotemporal fields, which propagate through a complex medium as if observing a scattering process in reverse, entering the medium as a complicated spatiotemporal field and arriving after propagation as a desired target field, such as a spatiotemporal focus. Time reversed waves have previously been demonstrated for relatively low frequency phenomena such as acoustics, water waves and microwaves. Many attempts have been made to extend these techniques into optics. However, the much higher frequencies of optics make for very different requirements. A fully time reversed wave is a volumetric field with arbitrary amplitude, phase and polarisation at every point in space and time. The creation of such fields has not previously been possible in optics. We demonstrate time reversed optical waves with a device capable of independently controlling all of light's classical degrees of freedom simultaneously. Such a class of ultrafast wavefront shaper is capable of generating a sequence of arbitrary 2D spatial/polarisation wavefronts at a bandwidth limited rate of 4.4 THz. This ability to manipulate the full field of an optical beam could be used to control both linear and nonlinear optical phenomena.