Optical limiting — a manner of telecom switching without the use of electronics — is an all-optical method that could improve the speed and capacity of Internet communications. A material created using tellurium nanorods — produced by naturally occurring bacteria — is an effective nonlinear 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.
While most optical materials are chemically synthesized, the new technology uses a biologically based nanomaterial that is less expensive and less toxic. Using bacteria to create the nanocrystals suggests an environmentally friendly route of synthesis.
Light at very high intensity, such as that emitted by a laser, can have unpredictable polarizing effects on certain materials. Suitable nonlinear materials that can withstand the effects have not previously been found. The goal is to find a material that can effectively reduce the light intensity, allowing for a device to be developed that could prevent damage by that light.
The nanocomposite, made up of biologically generated elemental tellurium nanocrystals and a polymer, was used to build an electro-optic switch — an electrical device used to modulate beams of light — that is immune to damage from a laser.
The biologically generated tellurium nanorods are especially suitable for photonic device applications in the mid-infrared range such as biomedical, environmental, and security-related sensing as well as laser processing and fiber optic and free-space communications. Work will continue to expand the material's potential for use in all-optical telecom switches, which is critical in expanding broadband capacity.