“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 optical and free-space communications.”Werner Blau
An international group of researchers has produced a new biologically based opticalnanocomposite material that helps protect against strong light. The material, which consists of biologically generated elemental tellurium nanocrystals as well as a polymer, could protect electronic devices from attack by high-intensity bursts of light, such as emitted by common lasers aimed at aircraft, drones, surveillance cameras and other equipment, and could also find applications in improving the capacity of high-speed optical networking.
As explained in Nature Communications [Wang et al. Nat. Commun. (2019) DOI: 10.1038/s41467-019-11898-z], the nonlinear optical material was developed from tellurium nanorods that produced bacterially formed nanocrystals. The researchers had shown selenite-respiring bacteria and how it forms separate areas of elemental selenium, before assessing how this could also be achieved with tellurium oxyanions, with tellurium having potential useful application in the field of nanophotonics being somewhat of a surprise.
While the majority of optical materials are chemically synthesized, the use of a nanomaterial is cheaper and offers less toxicity. The team expect the material and its performance will become a key material for next-generation optoelectronic and photonic devices, with the use of bacteria to produce the nanocrystals being an environmentally friendly manner of synthesis. The biologically generated tellurium nanorods are particularly useful for photonic device applications in the mid-infrared range.
Nonlinear optical measurements demonstrate the material’s strong saturable absorption and nonlinear optical extinctions induced by Mie scattering over temporal and wavelength ranges, with tellurium particles exhibiting superior optical nonlinearity than graphene. As light emitted at very high intensity can have an unpredictable polarizing effect on some materials, researchers have been attempting to identify nonlinear materials able to withstand such effects, especially one that can reduce the light intensity to prevent devices being damaged.
In addition, the team explored ways of using the material to build an electro-optic switch that can modulate beams of light, bringing telecom switching without the need for electronics but through the use of an all-optical approach to improve the speed and capacity of internet communications. As researcher Werner 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 optical and free-space communications”.
They now hope to further extend the potential uses of the material in all-optical telecom switches, which are key for expanding broadband capacity, especially as all-optical switches could assist upgrades to optical fiber to achieve greater bandwidth and switching speeds.