Synopsis: Enhancing Electrostriction with Metamaterials

Theoretical calculations show that an electric-field-induced strain, called electrostriction, can be increased (or decreased) by forming composite materials.
Synopsis figure
Mike Smith/University of Sydney

All dielectric materials deform in an electric field because of forces on induced dipoles. Typically, this “electrostriction” is quite small, but theoretical work has now shown that combining different dielectrics together in a metamaterial can boost (or reduce) the amount of deformation. The ability to engineer electrostriction could allow tuning of optical-acoustic interactions that are important in optical fibers and for processing microwave-frequency signals.

When an electric field is applied to a dielectric, it induces tiny dipoles inside the crystal. The electric field will also try to rotate the dipoles into alignment, causing a slight stretching of the crystal in the field direction. Because electrostriction depends on the field to both induce and rotate the dipoles, it is proportional to the square of the field strength. A similar (but stronger and linear) mechanical response occurs in piezoelectric materials.

Despite its relative weakness, electrostriction is the driving mechanism behind stimulated Brillouin scattering (SBS), which is an interaction between light and sound waves that occurs in optical waveguides. SBS is often a nuisance, but researchers have harnessed it to produce lasers and fiber-based signal processors. Mike Smith of the optics consortium CUDOS at the University of Sydney, Australia, and his colleagues demonstrate that SBS and related effects might be controlled by combining materials with different electrostrictive properties. They formulated a theoretical expression for the electrostriction in a metamaterial containing an array of nanospheres. The calculations show that embedding silver spheres in silica, for example, gives 3 times higher electrostrictive strain than pure silica, while other combinations reduce the electrostriction to near zero values. Surprisingly, the authors also found that a metamaterial can be electrostrictive even if none of the constituent materials exhibit electrostriction.

This research is published in Physical Review B.

–Michael Schirber


Features

More Features »

Announcements

More Announcements »

Subject Areas

Metamaterials

Previous Synopsis

Next Synopsis

Atomic and Molecular Physics

Symmetric Radium Atoms

Read More »

Related Articles

Focus: Making Shear Waves for Ultrasonic Imaging
Acoustics

Focus: Making Shear Waves for Ultrasonic Imaging

New filter allows shear waves to be produced efficiently, which could lead to higher resolution ultrasound images. Read More »

Focus: <i>Image</i>—Sound Waves Guided Along Curvy Path
Condensed Matter Physics

Focus: Image—Sound Waves Guided Along Curvy Path

A new image from 3D computer simulations demonstrates that tiny, randomly arranged pillars can allow an acoustic wave to be efficiently guided through an arbitrarily shaped channel. Read More »

Synopsis: Metamaterial Inverts the Hall Effect
Materials Science

Synopsis: Metamaterial Inverts the Hall Effect

A metamaterial that looks like chainmail has a Hall coefficient whose sign is flipped compared to the material it’s made from. Read More »

More Articles