Optical fibres might be useful for nuclear waste exploration

Image credit: UrFU / Vladimir Petrov.

Infrared optical fibres able to retain their properties and performance in the presence of high levels of ionizing radiation might be usefully deployed in applications such as determining the composition of nuclear waste, according to the team behind their recent development.

Researches at the Ural Federal University (UrFU) – in Yekaterinburg, Russia – say the fibres are nontoxic and, as studies have shown, retain their outstanding properties when treated with ionizing beta radiation at doses of up to 1 MGy. An article describing the research is being published in the journal Optical Materials.

“This opens up the prospect of application of light guides made of the obtained fibres in conditions of intense ionizing radiation. That is, not only in the traditional field of optoelectronics, but also in laser surgery, endoscopic and diagnostic medicine, in determining the composition of hazardous waste from the nuclear industry, and in space,” says Liya Zhukova, Chief Scientist of the Laboratory, Professor of the Department of Physical Chemistry and Chemistry of Colloids at UrFU.

Because the fibres are capable of receiving and transmitting radiation from space objects, they can be embedded in infrared space telescopes, replacing massive mirrors and lenses. The lifespan of the fibres will be longer than the life cycle of the telescopes themselves, the developers claim.

Fibres are also highly productive in the (non-hazardous for humans) terahertz radiation region (between the region of mid- and far-infrared radiation, on the one hand, and microwave radiation, on the other). This means that the resultant fibre optic cables could be used to develop equipment that could become a safe substitute for magnetic resonance imaging and x-rays – in medicine or in the process of pre-boarding scanning of passengers and their luggage. It would not require the use of cumbersome and expensive metal detectors, and passengers would not even feel that they are being screened.

The fibres are based on crystals of AgBr-AgI. They can be produced using an environmentally friendly, waste-free and energy-saving method, according to developer Liya Zhukova. Chemists from UrFU synthesized a sample of almost one hundred percent purity and for the first time in the world grew silver bromide and silver iodide monocrystals from it.

“The grown crystals have extremely high transparency, plasticity, as well as photostability and non-hygroscopicity – the ability to retain their properties under the influence of light without interacting with moisture,” said Anastasia Yuzhakova, a Junior Researcher at the Ural Federal University’s Science Lab of Fiber Technology and Photonics.

Using computer modeling, the group determined the optimal conditions for manufacturing homogeneous infrared optical fibers with unique characteristics from monocrystals. The computer simulation was confirmed by experimental data. Scientists successfully obtained fibers using the author’s technology and equipment, cylindrical blanks with improved optical and mechanical properties.

“Based on monocrystals of AgBr-AgI… we created optical fibres with the widest infrared transmission range to date – from 3 to 25 microns. The transparency of the fibres reaches 70-75%, which corresponds to theoretically possible values for crystals of AgBr-AgI… At the same time, the optical losses of the fibres reach extremely low values,” said Anastasia Yuzhakova.