First laser radio transmitter
You never heard Dean Martin like that.
This recording of Martin's classic Vollar was transmitted wirelessly using a semiconductor laser – the first time a laser was used as a radio frequency transmitter.
Image Caption: This device uses a frequency comb laser to emit and filter the microwave wirelessly. The laser uses different frequencies of light strikes together to create microwave radiation. The "beats" emitted from the laser are reminiscent of a painting (right) by Spanish artist Ján Miro. Called "Blue II". The researchers used this to send a wireless song to the receiver. (Photo courtesy of Marco Picardo / Harvard SEAS).
In an article published in Procedures Of the National Academy of Sciences, researchers from the School of Engineering and Applied Sciences at Harvard University. Paulson (SEAS) has demonstrated a laser that can emit microwaves wirelessly, regulate them and receive external radio frequency signals.
"The study opens the door to new types of hybrid photonic electronic devices and is the first step towards fast Wi-Fi," said Federico Capasso, Wallace Applied Physics and Senior Research Fellow of JointHealth Engineering, SEAS and Senior Research Writer.
This research builds the previous work from the Capasso Laboratory. In 2017, researchers discovered that the infrared frequency comb and quantum laser laser could be used to generate terahertz frequencies, wavelengths of the sub-range of the electromagnetic spectrum that could transmit data hundreds of times faster than today's wireless. In 2018, the team found that quantum-frequency laser combs could also be used as integrated transmitters or receivers to efficiently encode information.
Now, researchers have noticed a way to extract and transmit wireless signals to laser frequency combos.
Unlike conventional lasers, which emit a single frequency of light, the laser frequency combs emit multiple frequencies simultaneously, at intervals equal to the teeth of a comb. In 2018, the researchers discovered that within the laser, different frequencies of light beat together to produce microwave radiation. The light inside the laser cavity caused the electrons to oscillate in microwave frequencies – which are in the communications domain.
"If you want to use this device for Wi-Fi, you should be able to put useful microwave signal information and extract the information from the device," said Marco Piccardo, postdoctoral fellow at SEAS and the first author of the paper.
The first thing that the new device needed to transmit microwave signals is an antenna. Then, the researchers etched a gap into the top electrode of the device, creating a dipole antenna (like rabbit ears on top of the old TV). Next, they are modulated in a frequency comb to encode information about the microwave radiation generated by the light striking of the comb. Then, using the antenna, refrigerators are cooled from the device, containing the encoded information. The radio signal is received by a beam antenna, filtered and sent to the computer.
The researchers also proved that the laser radio can receive signals. The team was able to remotely control laser behavior using microwave signals from another device.
"The all-in-one integrated device delivers great promise for wireless communication," Picard said. "While the dream of wireless communications Terraz is still far away, this study provides a clear road map showing how to get there."
The Harvard Office for Technology Development has protected the intellectual property rights of this project and is examining opportunities for commercialization.
This study was signed by Michel Tamagnona, Benedict Schwartz, Paul Chevalier, Noa A. Rubin, Jungry Wang, Christine Wang, Michael K. Connors, Daniel McNulty and Alexei Belianin. It is supported in part by the National Science Foundation.