Modern mobile devices use components that use acoustic waves (vibrations) to filter or delay signals. The currently available components in this area (SAW-filters, Surface Acoustic Wave-filters) make further reductions in the size of mobile devices difficult, if not impossible, and furthermore have limitations as to the bandwidth that can be obtained.
A research team from Caltech (California Institute of Technology) has, however, developed new versions of these components that offer abilities that were not possible with earlier generations. These new components (phononic components) can be used in sensors, quantum computers and smartphones.
The new phononic components contain parts that vibrate extremely fast – moving back and forth tens of millions of times per second. This became possible thanks to the use of cylinders of silicon nitride that are only 90 nm thick. These are arranged in a grid, where different grid patterns result in different characteristics for the components.
The researchers have demonstrated that these arrays can act as tunable filters for signals with different frequencies. Also, it turns out that these components can operate as one-way valves for high-frequency waves. The ability to transmit waves in only one direction is beneficial for signal strength, because interference is reduced.
The research offers opportunities for the design of new components – transistors and RF isolators based on phonons instead of electrons.
The results of this research have been published in Nature Nanotechnology and Nature.