Scientists have developed a novel method to deflect laser beams using only air. The technique, which is based on a phenomenon called acousto-optic interaction, could enable new kinds of devices that can perform functions that are not possible with existing technology.
Acousto-optic interaction describes how sound waves can affect the propagation of light waves. When sound waves travel through a medium, such as air, they create a pattern of dense and less dense areas. These areas have different refractive indices, which means they bend light differently. By controlling the frequency and amplitude of the sound waves, one can create a grating that acts like a mirror for light.
This is the principle behind the method developed by a team of researchers from the University of Maryland, the U.S. Army Research Laboratory, and the Johns Hopkins University Applied Physics Laboratory. They used sound waves to create an invisible grating in the air that can deflect laser beams with high power and quality.
“We have demonstrated for the first time that it is possible to deflect a laser beam using only air,” said Dr. Howard Milchberg, professor of physics and electrical and computer engineering at the University of Maryland and senior author of the study.
The researchers used a device called a piezoelectric transducer to generate sound waves in the ultrasonic range, which are inaudible to humans. They placed the device near a laser beam and adjusted the sound frequency to match the wavelength of the laser. This created an air grating that could reflect up to 30% of the laser power.
The method has several advantages over conventional acousto-optic devices, which use solid materials such as crystals or glass to create gratings. First, it can achieve much larger deflection angles, which means it can redirect light more efficiently. Second, it can handle higher laser powers without damaging the medium or causing thermal effects. Third, it can be easily tuned and switched on and off by changing the sound frequency or amplitude.
“This is a major breakthrough as we have been able to achieve deflection angles that are orders of magnitude larger than what is possible with conventional acousto-optic devices,” said Dr. Ryan J. Smith, research physicist at the U.S. Army Research Laboratory and lead author of the study.
The method has potential applications for high-tech devices such as laser communication, remote sensing, and optical switching. For example, it could be used to create a wireless network that uses lasers to transmit data in the air. It could also be used to steer laser beams for scanning or imaging purposes. Moreover, it could be used to create dynamic holograms or optical illusions in the air.
“This technique opens up new possibilities for manipulating light in air. It could enable new kinds of devices that can perform functions that are not possible with existing technology,” said Dr. Eric Rosenthal, research physicist at the Johns Hopkins University Applied Physics Laboratory and co-author of the study.
The researchers have applied for a patent for their method, which they call “air-based dynamic diffraction gratings” or “air gratings” for short. They hope to further improve their technique and explore its applications in various fields.
“The beauty of this method is that it is very simple and robust. It does not require any special materials or equipment, and it works in any atmospheric condition,” said Dr. Kamil Mielczarek, postdoctoral researcher at the University of Maryland and co-author of the study.
“We have shown that air can act as a tunable mirror that can be controlled by sound. This is a new way of thinking about how to manipulate light in air,” said Dr. Yogesh Joglekar, associate professor of physics at Indiana University-Purdue University Indianapolis and an expert on acousto-optic interaction who was not involved in the study.
Relevant articles:
– Laser Beams Deflected Off of Nothing but Air for First Time Ever in Breakthrough Patent Pending Process, The Debrief, October 18, 2023
– No mirrors: In a first, lasers deflected using only air, Interesting Engineering, October 4, 2023
– Scientists Have Managed To Deflect Lasers Using Only Air For The First Time Ever, Wonderful Engineering, October 5, 2023
– Scientists deflect lasers with air, Inquirer Technology, October 10, 2023