Negative group velocity and three-wave mixing in dielectric crystals

TL;DR

This paper investigates the unique properties of optical parametric amplification involving backward phonons with negative group velocity in dielectric crystals, proposing novel nonlinear-optical devices with metamaterial-like features.

Contribution

It introduces the concept of three-wave mixing with backward phonons in dielectric crystals, highlighting similarities to negative-index metamaterials and proposing new photonic device designs.

Findings

Optical parametric amplification with backward phonons exhibits unique features.

Backward phonons with negative dispersion enable novel nonlinear optical effects.

Proposed devices mimic negative-index metamaterial properties.

Abstract

Extraordinary features of optical parametric amplification of Stokes electromagnetic waves are investigated, which originate from three-wave mixing of two ordinary electromagnetic and one backward phonon wave with negative group velocity. A similarity with the counterpart in the negative-index plasmonic metamaterials and differences with those utilizing contra-propagating ordinary electromagnetic waves as well as electromagnetic and acoustic phonon waves are shown. They stem from backwardness of optical phonons with negative dispersion. Nonlinear-optical photonic devices with the properties similar to those predicted for the negative-index metamaterials are proposed.