Laser is used as a radio frequency transmitter for the first time by researchers at Harvard School of Engineering John A. Paulson in the United States.
They demonstrated that the laser can wirelessly emit microwaves, modulate and receive external radio frequency signals.
"The research opens the door for new types of hybrid electronic photonics and is the first step towards ultra-fast Wi-Fi," says Federico Capasso, senior author of the study.
In 2017, the researchers found that the infrared frequency comb in a quantum cascade laser can be used to generate the frequencies of terahertz, the sub-millimeter wavelengths of the electromagnetic spectrum that can transmit data hundreds of times faster than today's wireless platforms.
In 2018, the team found that quantum cascading laser frequency combs could act as integrated transmitters or receivers for effective information encryption.
Now, the researchers have figured out how to extract and transmit wireless signals from the Czech particles for laser particles.
Unlike conventional lasers that emit a single light frequency, laser frequency combs simultaneously emit more frequencies, evenly distributed to resemble teeth on the comb.
The team found that in the interior of the laser, the different light frequencies beat together to generate microwave radiation. The light inside the laser gap causes electrons to oscillate at microwave frequencies – which are within the communication spectrum.
"If you want to use this Wi-Fi device, you should be able to put useful information into microwave signals and get that information out of the device," said Marko Picardo, the first author of the paper.
The first thing the new device was supposed to transmit the microwave signals was the antenna.
The researchers engraved a gap in the device's upper electrode, creating a dipole antenna (like the ears for a rabbit on the top of an old TV).
They then modulated a frequency comb to encode information about microwave radiation created by the light of combing the comb. Using the antenna, the microwaves radiate from the device, contain encrypted information. The radio signal is received from the horn antenna, filtered and sent to the computer.
The researchers also showed that laser radio can receive signals. The team was able to remotely control the behavior of the laser using microwave signals from another device.
"This all-in-one integrated device has a great promise of wireless communication," Picardo said. "While terahertz's wireless communication dream is still far away, this research provides a clear roadmap indicating how to get there."