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Active Metamaterials

Metamaterials are a new sort of optical material constructed from nano-engineered elements

Nano Engineering StructuresMetamaterials are built from individual elements, designed to mimic the electromagnetic response of atoms. They are built from repeating many such elements to make a new solid material, where each nano-engineered element is smaller than the wavelength of light. Such materials can have extremely unusual properties, such as negative refractive indices which enables the focussing of light much smaller than its wavelength (super-lensing), or electromagnetic cloaking (hiding an object within a metamaterial cloak).

Self-assembling Scalable Gyroid Metamaterialsself-assembling scalable gyroid metamaterials
Using scaffolds of block co-polymers built of organic molecules that can be induced to separate into nanoscale compartments, we create large area gold and silver metamaterials. The unit cells have sizes we can tune from 30-60nm, and the individual struts are 5-15nm across. A wide variety of optical properties can be produced, including enhancing photovoltaics and sensing.

Fexible Elastic Coloured Mirrorsflexible elastic coloured mirrors
By folding sub-micron plastic transparent layers, we create multilayers which selectively reflect specific colours of light. By making these elastic, and pressurising such bubbles, we make balloons with chromatic hearing: they change colour on stretching.

Roll-up Scalable Metamaterialsroll-up scalable metamaterials
Since metamaterials for visible light require sub-100 nm sized elements, their fabrication has been expensive, time-consuming, and only available in miniscule amounts. Using a new technique in which ultra-thin metal and polymer bi-layers are floated onto the surface  of water and then rolled up, we have made new metamaterials in which light can propagate anisotropically.

Metallo-dielectric Stacksmetallo-dielectric stacks
Using the roll-up technique, we fabricate stacks of nm-thick metals that trap light in successive layers. Light is confined in different parts of the structure, and can be flipped by injecting a pulse of light.

Nano-pillar Array Metamaterial FiltersNano-pillar array metamaterial filters
Using arrays of coated silicon or carbon nanotube pillars, optical filters with different properties can be constructed.

References

[4] S. Vignolini , N. A. Yufa , P. S. Cunha , S. Guldin , I. Rushkin , M. Stefi k , K. Hur , U. Wiesner , J.J. Baumberg , U. Steiner, Advanced Materials (2011); DOI:10.1002/adma.201103610

[3] G. Kamita, M. Kolle, F. Huang, J. J. Baumberg, U. Steiner, Optics Express 20, 6421 (2012)

[2] N. Gibbons, J. J. Baumberg – Phys. Rev. B 85, 165422 (2012)

[1] “Scalable Cylindrical Metallo-dielectric Metamaterials”, N. Gibbons, J.J. Baumberg, C.L. Bower, M. Kolle, U. Steiner, Advanced Materials 21, 3933 (2009). [pdf]