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Fiber optics make Internet possible. These are fine glbad threads, as fine as a human hair, produced to transmit light. Optical fibers carry thousands of gigabytes of data per second around the world and vice versa. The same fibers also guide ultrasonic waves, which are quite similar to those used in medical imaging.
These two wave phenomena – optical and ultrasonic – have fundamentally different attributes. The fibers are designed to maintain the propagation of light strictly within a central region, as any light entering outside of this region represents the loss of a valuable signal. On the other hand, the ultrasonic waves can reach the outer limits of the fibers and probe their environment.
Intuition, and much of the training given in the basic courses of mechanics and optics of the first university cycle, encourage us to consider the light and sound waves as separate and unrelated entities. But this perspective is incomplete. The propagation of light can cause oscillations of ultrasonic waves, as if it 's been a kind of transducer, because of the basic rules of electromagnetism. Similarly, the presence of ultrasound can disperse and modify the light waves. Light and sound waves can interact / affect each other and are not necessarily separate and unbound.
The field of research of opto-mechanics is dedicated to the study of this interaction. Such studies, particularly on fibers, can be very useful and give surprising results. For example, earlier this year, research groups from the Bar-Ilan University in Israel and EPFL in Switzerland developed detection protocols allowing fiber optics to be used in research. "listen" to the outside of an optical fiber where they can not "look", based on an interaction between light waves and ultrasound. By launching light waves into a single end of a standard telecommunication fiber, the measurement facility could identify and map liquid media for miles. These results were published in two articles (in the journal Nature Communications). These methods can be used in oil and gas pipelines, ocean and lake monitoring, climate studies, desalination plants, process control in chemical industries, etc.
The mutual effects of light and sound waves propagating in a fiber continue to arouse interest and attention. In an article that has just been published in the journal Letters of Applied Physics – PhotonicsProfessor Avi Zadok's research group, the Faculty of Engineering and the Institute of Nanotechnology and Advanced Materials at Bar-Ilan University, advanced this study. The group has developed a distributed spectrometer, a measurement protocol for mapping the local power levels of several optical wave components over several kilometers of fiber. "The measurements show how the generation of ultrasonic waves can mix these optical waves. Rather than propagating independently, opto-mechanical interactions lead to the amplification of certain optical waves and the attenuation thereof in a complicated way. The complex dynamics observed, however, is fully taken into account by a corresponding model, "said Zadok.
The report by Zadok and PhD students Yosef London, Hagai Diamandi and Gil Bashan is featured in the journal as an "Editor's Choice". This new overview of opto-optical fiber optics can now be applied to longer-range, higher-range sensor systems. spatial resolution and better accuracy to facilitate, for example, leak detection in reservoirs, dams and pipelines.
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