Science and Technology Daily, Beijing, February 1 (Reporter Liu Xia) American scientists published a paper in the latest issue of Physical Review X, saying that by launching a doughnut-shaped powerful laser into the air, they produced a kind of optical pulse, which acts like an optical fiber and can transmit data for 45 meters. The relevant technology can finally be used to detect radioactive substances several kilometers away.
Like lasers, dense beams can also transmit information and energy, but these beams tend to widen when they travel, resulting in loss of information and energy. Therefore, when used for communication, such beams are usually confined to glass tubes or optical fibers, but strong optical pulses will melt the optical fibers. In the latest research, researchers at the University of Maryland have created a kind of "optical fiber" in the air.
In order to shape the air into a fibrous structure called "air waveguide", the research team used a powerful laser with a duration of only 300 trillionths of a second, which can heat and rearrange the air particles, making the air reflect any subsequent beam in the same way as the traditional optical fiber wall. After the first laser was launched, the air guide was stuck around. The researchers then launched the second laser, which lasted 1000 times longer than the first laser, and finally produced a 45-meter "optical fiber" from the air.
In 2014, the research team used different lasers to produce an air guide of only 70 cm. This time, they used a doughnut laser beam to increase the length of the air guide by nearly 65 times. The researchers said that the latest method can be used to make kilometer-long air guides.
However, Aurelian Ouar of the Paris Institute of Technology said that to achieve the above goals, higher energy laser and completely uniform and symmetrical doughnut beam are required, which is not only costly, but also technically challenging. In January 2023, the Wuar team used lasers to create an air guide, which captured and guided light, and produced lightning rods from the air.
The researchers said that the long air duct could be used for remote detection of radioactive substances. When irradiated by the waveguide, the radiation emitted by these radioactive substances will become very strong, which can be identified by remote detectors.
Source: Science and Technology Daily
