Science & Technology (Commonwealth Union) – A group of engineers has achieved significant progress in creating the smallest possible seismic vibrations ever produced.
The researchers have developed a device called a surface acoustic wave phonon laser, which may eventually enable the production of more advanced microchips for smartphones and other wireless technologies—potentially leading to devices that are more compact, quicker, and more energy-efficient.
The research was led by Matt Eichenfield, soon to join the faculty at the University of Colorado Boulder, together with experts from the University of Arizona and Sandia National Laboratories. Their findings were published on January 14 in the journal Nature.
This innovative approach makes use of a process known as surface acoustic waves, or SAWs. These waves behave in a similar way to sound waves, but instead of moving through the air, they travel along the surface layer of a material.
On a much larger scale, natural earthquakes also produce SAWs that spread across the Earth’s surface, causing the ground to shake and sometimes resulting in serious destruction.
SAWs play a crucial role in daily life hence its application could play a crucial role.
“SAWs devices are critical to the many of the world’s most important technologies,” explained Eichenfield, senior author of the new study and Gustafson Endowed Chair in Quantum Engineering at CU Boulder. “They’re in all modern cell phones, key fobs, garage door openers, most GPS receivers, many radar systems and more.”
In smartphones, SAWs already function as tiny filters. The radios in a phone pick up radio signals transmitted from a cell tower and convert them into minute vibrations. This process enables internal chips to filter out interference and background noise with ease. Afterward, the same component changes those vibrations back into radio waves.
In their latest research, Eichenfield and his colleagues created a new method for producing SAWs through the use of a “phonon laser.” The device operates in a similar way to an ordinary laser pointer, but instead of emitting light, it generates vibrations.
Alexander Wendt, a graduate researcher at the University of Arizona and the study’s lead author indicated that we can imagine something like the ripples from an earthquake, but occurring only across the surface of a small microchip.
At present, most SAW systems rely on two separate chips along with an external power supply to create these waves. By contrast, the team’s new design operates on a single chip and could potentially generate much higher-frequency SAWs while being powered simply by a battery.
To grasp how the team’s new SAW device operates, it is useful to compare it with a conventional laser.
Most of the lasers in use today are called “diode lasers.” These function by reflecting a light beam back and forth between two tiny mirrors built onto the surface of a semiconductor chip. Each time the light travels between the mirrors, it interacts with atoms in the semiconductor material, which are energized by an electric field supplied by a battery or similar power source. These energized atoms release additional light, gradually strengthening the beam.
Eichenfield indicated that the diode lasers form the basis of much of modern optical technology because they can run directly from a simple electrical source, without requiring another laser to drive them.
He indicated that their goal was to create something comparable to that type of laser, but designed for surface acoustic waves.
With this aim, the researchers created a small bar-shaped device measuring roughly half a millimeter in length.
