Using a nanoscale drum, scientists have built a laser that uses sound waves instead of light like a conventional laser. They call it a Phaser. Because laser is an acronym for “light amplification by stimulated emission of radiation,” these new contraptions – which exploit particles of sound called phonons – should properly be called phasers. Such devices could one day be used in ultrasound medical imaging, computer parts, high-precision measurements, and many other places.
Sound lasers work on a similar principle. For Mahboob and his team’s phaser, a mechanical oscillator jiggles and excites a bunch of phonons, which relax and release their energy back into the device. The confined energy causes the phaser to vibrate at its fundamental frequency but with at a very narrow wavelength. The sound laser produces phonons at 170 kilohertz, far above human hearing range, which peters out around 20 kilohertz. The entire device is etched onto an integrated circuit that’s about 1 cm by 0.5 cm.
Phonons require a medium to travel through, which means the phaser waves are confined to their device for the time being.
A tiny part of the device translates the mechanical vibration into an oscillating electrical signal, which could serve as a tiny clock.
Other potential applications, once the technology matures further, would be to use the ultrasound frequencies to scan objects or people for safety or medical purposes. Alternatively, the extremely narrow sound wavelengths could be used for high-precision measurement
An electromechanical resonator harboring an atomlike spectrum of discrete mechanical vibrations, namely, phonon modes, has been developed. A purely mechanical three-mode system becomes available in the electromechanical atom in which the energy difference of the two higher modes is resonant with a long-lived lower mode. Our measurements reveal that even an incoherent input into the higher mode results in coherent emission in the lower mode that exhibits all the hallmarks of phonon lasing in a process that is reminiscent of Brillouin lasing.