Unidirectional Amplification and Shaping of Optical Pulses by Three-Wave Mixing with Negative Phonons

TL;DR

This paper explores a novel nonlinear optical process using negative phonons in crystals to enhance frequency conversion and pulse shaping, potentially replacing complex metamaterials with more accessible materials.

Contribution

It demonstrates the feasibility of using elastic waves with contra-directed velocities in crystals for efficient three-wave mixing, eliminating the need for negative-index metamaterials.

Findings

Enhanced frequency-conversion efficiency in short pulse regime

Elimination of damping effects of optical phonons

Potential for new unidirectional Raman amplifiers and pulse shapers

Abstract

A possibility to greatly enhance frequency-conversion efficiency of stimulated Raman scattering is shown by making use of extraordinary properties of three-wave mixing of ordinary and backward waves. Such processes are commonly attributed to negative-index plasmonic metamaterials. This work demonstrates the possibility to replace such metamaterials that are very challenging to engineer by readily available crystals which support elastic waves with contra-directed phase and group velocities. The main goal of this work is to investigate specific properties of indicated nonlinear optical process in short pulse regime and to show that it enables elimination of fundamental detrimental effect of fast damping of optical phonons on the process concerned. Among the applications is the possibility of creation of a family of unique photonic devices such as unidirectional Raman amplifiers and femtosecond pulse shapers with greatly improved operational properties.