The first of its kind laser radio transmitter was born.

A group of researchers from Harvard University was able to broadcast an audio recording of one of the musical works using a radio transmitter, a key component of which was a semiconductor laser. This laser is used as a source of radio-frequency waves, a generator, in addition, it also performs the functions of modulating the transmitted and demodulating received signals. These studies are the first steps towards the creation of new types of hybrid electronic photo-optical devices, which will become the basis for the operation of ultra-high-speed wireless communication systems, Wi-Fi of the next generation. The creation of a laser radio transmitter was a continuation of the work carried out by researchers in 2017. Then the scientists discovered that the infrared frequency comb created by a quantum cascade laser can be used to produce radio signals in the terahertz range, the submillimeter range of the electromagnetic spectrum. Signals in this range have the potential to transmit data in large quantities and at speeds far exceeding the capabilities of modern wireless communications. And in 2018, scientists found that quantum cascade lasers can work simultaneously as receivers and transmitters, very effectively encoding information in the emitted signals. Unlike conventional lasers, which emit light at a single frequency, laser frequency combs emit a whole set of fixed frequencies simultaneously. These fixed frequencies are evenly spaced on the spectrum line and resemble comb teeth. And if you select certain frequencies from the comb created by the laser, then the electrons inside the laser resonator begin to oscillate with microwave frequencies that are within the spectrum that can be used for wireless communications. As in traditional radio transmitting devices, a dipole antenna is used in the laser transmitter. The coding of the transmitted information is performed using frequency modulation modulation. However, in this case, a second, whip antenna is used to receive the signal, the signal from which is fed to the laser frequency comb, where it is filtered, extracted and demodulated. After all this, the signal is digitized and transferred to a computer for further mathematical processing. “This laser component, which performs almost all the basic functions, can become part of the hybrid integrated circuits that will be used in next generation wireless communications,” the researchers write, “So far, experts are only dreaming of using terahertz waves in radio communications, but our work is the first and a big step towards the realization of these dreams in reality. “