An international team of researchers has reported a new way to safeguard aircraft, drones, surveillance cameras and other equipment against high intensity bursts of light, such as laser attacks.

Superior manner of telecom switching

The work, just published in the journal 'Nature Communications', also describes a superior manner of telecom switching that doesn’t require electronics; instead, the all-optical method could improve the speed and capacity of internet communications, which could in turn remove a notable roadblock in moving from 4GLTE to 5G networks.

The team reported that a material created using tellurium nanorods – produced by naturally occurring bacteria – is an effective non-linear optical material, capable of protecting electronic devices against high-intensity bursts of light, including those emitted by inexpensive household lasers targeted at aircraft, drones or other critical systems.

The researchers describe the material and its performance as a material of choice for next-generation optoelectronic and photonic devices. Seamus Curran, a physics professor at the University of Houston and one of the paper’s authors, said while most optical materials are chemically synthesised, using a biologically based nanomaterial proved less expensive and less toxic.

Using bacteria to create the nanocrystals

By using bacteria to create the nanocrystals the researchers have developed an environmentally friendly means of making them, and the results are superior to those obtained from graphene.

Bacillus beveridgei strain MLTeJB, composed of aggregated Te(0) shards; The bacteria are readily evident as are the surrounding rods. Credit: USGS.
Professor Curran said: “We found a cheaper, easier, simpler way to manufacture the material. We let mother nature do it.”

The findings grew out of earlier work by Curran and his team, working in collaboration with professor of physics of advanced materials, Werner J Blau, of Trinity College Dublin, and Professor Ron Oremland of the US Geological Survey. Curran initially synthesised the nanocomposites to examine their potential in the photonics world and holds a US and international series of patents for that work.

Light at very high intensity, such as that emitted by a laser, can have unpredictable polarising effects on certain materials and physicists have long been searching for suitable non-linear materials that can withstand the effects.

One main goal has been to find a material that can reduce the light intensity so as to prevent damage by that light.

By using the nanocomposite, made up of biologically generated elemental tellurium nanocrystals and a polymer, the team has built an electro-optic switch – an electrical device that modulates beams of light – that is immune to laser damage.

Prof Oremland noted that the current work grew out of 30 years of basic research, stemming from the initial discovery of selenite-respiring bacteria and that the bacteria form discrete packets of elemental selenium.

“From there, it was a step down the periodic table to learn that the same could be done with tellurium oxyanions,” he said. “The fact that tellurium had potential applications in the realm of nanophotonics came as a serendipitous surprise.”

Prof Blau, Trinity, said the biologically generated tellurium nanorods are especially suitable for photonic device applications in the mid-infrared range.

'Hot technological topic'

Professor Blau said: "This wavelength region is becoming a hot technological topic as it is useful for biomedical, environmental and security-related sensing, as well as laser processing and for opening up new windows for fiber-optic and free-space communications."

Work will now continue to expand the material’s potential for use in all-optical telecom switches, which is critical for expanding broadband capacity.

Prof Curran added: “We need a massive investment in optical fiber. We need greater bandwidth and switching speeds. We need all-optical switches to do that.”

In addition to Prof Blau, Professor Hongzhou Zhang from Trinity was also involved with the research, along with Gaozhong Wang (from the Shanghai Institute of Optics and Fine Mechanics at the Chinese Academy of Sciences, but also affiliated with Trinity).