A new advancement in laser technology leverages concentrated beams of plasma to generate a glowing “lightsaber” that can transmit radio signals, opening new possibilities for wireless communication systems and even exploration of space.
The breakthrough, reported in a recent study in the IEEE Journal of Microwaves by researchers at North Carolina State University, showcases a laser-induced plasma antenna that can transmit radio waves in the very high frequency (VHF) range of around 30 megahertz.
The plasma transmitter’s novel ability to change its length and direction through manipulation of the laser’s beam offers an advantage over conventional antennas, which are limited by their physical dimensions that govern the frequencies they can transmit.
“The plasma beam antenna looks like a lightsaber and is tunable, meaning we should be able to transmit across a broad range of frequencies,” according to Prya Darshni, a doctoral student at NC State and one of the new study’s authors.
A Lightsaber Radio Antenna
The concept behind the antenna is simple: researchers blasted a laser through the air, which ionizes a narrow column of gas. The resulting structure, known as a plasma filament, is highly conductive.
Yet in order to transmit radio signals requires another application entirely: the use of a contactless antenna feed.
To achieve this, the NC State research team produced a metallic ring that essentially works like a capacitor, which allows the laser-induced plasma filament to pass through its center. Once this is connected to a radio-frequency generator, the ring produces an electromagnetic field that couples energy into the plasma.
This, in turn, allows the plasma “lightsaber” to transmit radio waves, all without requiring direct electrical contact.
From here, the researchers were able to successfully adjust the laser’s properties, and researchers can potentially change the antenna’s length and direction, which could create a very formidable new technology for situations that demand adjustable frequencies or changes in directional transmissions.
Space Technologies and More
Along with satellites and other space-based platforms, the new technology could also prove useful in areas where conventional antenna deployment systems introduce challenges due to weight and overall complexity.
While the research team has successfully demonstrated radio transmission with their technology by receiving signals, going forward, the plan is to expand by operating across a broader frequency range of frequencies.
“This is the first step, but it is a big step—it is the first time anyone has ever demonstrated that plasma-filament antennas can work,” Darshni said.
The team’s recent study, “Laser-Induced-Plasma-Filament Antenna Transmitting 30 MHz VHF,” appeared in the journal IEEE Journal of Microwaves.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.