Laser Threading Creates Large-Scale Metamaterials

A new laser-pulse technique has been used to create light-altering metamaterials in larger quantities than other techniques.

Researchers at the University of Cambridge have developed a new method of nanoassembly involving plasmon-induced laser threading of gold nanoparticle strings to produce conducting threads 12±2 nm wide. The chemically arranged nanoparticles form chains among barrel-shaped molecules called cucurbiturils (CB) that act as spacers and hold the chains apart in 0.9-nm gaps. Femtosecond laser pulses then trigger plasmons, which propagate along the chains and bind them together.

The laser-induced threading occurs on a large scale in water, and is tracked with a new optical resonance in the near-infrared corresponding to a hybrid chain/rod-like charge transfer plasmon.

An efficient route to manufacturing nanomaterials with light through plasmon-induced laser-threading of gold nanoparticle strings. Courtesy of Ventsislav Valev/University of Cambridge.

The width of the nanothreads depends on “the chain mode resonances, the nanoparticle size, the chain length and the peak laser power,” according to the study.

“We have controlled the dimensions in a way that hasn’t been possible before,” said researcher Dr. Ventsislav Valev, at the university. “It’s about finding a way to control that bridge between the nanoparticles.”

The ability to control the nanoparticle and metamaterial creation process could lead to a variety of potential applications. Among them are invisibility effects, military stealth technology, communications and renewable energy.

The research was published in Nature Communications (doi: 10.1038/ncomms5568).

For more information, visit www.cam.ac.uk.