Giant modulation of optical nonlinearity by Floquet engineering

TL;DR

This paper demonstrates the coherent, ultrafast, and giant modulation of optical nonlinearity in a magnetic insulator using Floquet engineering, enabling dynamic control of optical properties with potential applications in nonlinear optics.

Contribution

It introduces a method to coherently control and significantly modulate optical nonlinearity in a layered magnetic insulator via off-resonance Floquet driving, with experimental and theoretical validation.

Findings

Achieved on-off switching of second harmonic generation within 100 femtoseconds.

Observed modulation ratio exceeding 10 at high electric fields.

Theoretical Floquet calculations match experimental results.

Abstract

Strong periodic driving with light offers the potential to coherently manipulate the properties of quantum materials on ultrafast timescales. Recently, strategies have emerged to drastically alter electronic and magnetic properties by optically inducing non-trivial band topologies, emergent spin interactions and even superconductivity. However, the prospects and methods of coherently engineering optical properties on demand are far less understood. Here we demonstrate coherent control and giant modulation of optical nonlinearity in a van der Waals layered magnetic insulator, manganese phosphorus trisulfide (MnPS$_3$). By driving far off-resonance from the lowest on-site manganese $d$-$d$ transition, we observe a coherent on-off switching of its optical second harmonic generation efficiency on the timescale of 100 femtoseconds with no measurable dissipation. At driving electric fields of the order of 10$^9$ volts per metre, the on-off ratio exceeds 10, which is limited only by the sample damage threshold. Floquet theory calculations based on a single-ion model of MnPS$_3$ are able to reproduce the measured driving field amplitude and polarization dependence of the effect. Our approach can be applied to a broad range of insulating materials and could lead to dynamically designed nonlinear optical elements.