Optomechanical devices, which simultaneously confine light waves and mechanical waves to permit interaction between them, can be used to sense motion. In smartphones, these electronic components switch the touchscreen between portrait and landscape when they detect rotation.
The new device is said to be based on a 24µ silicon disk supported by a silicon dioxide central pedestal.
According to the researchers, the light waves are confined at the edge of the disk by total internal reflection. This is an optical phenomenon whereby light within a medium is reflected from the surrounding surfaces – such as the air interface – back into the medium.
Light waves are therefore compressed near the disk edge and travel around the disk’s concentric rings, whereas mechanical vibrations can propagate throughout the material.
However, the rings create frequency regions in which mechanical waves cannot propagate, so that they are confined to the outside edge of the disk, where they interact directly with the light waves.
"Confining light waves and mechanical waves to the disk edge enables us to boost their interaction, which is useful for exploring quantum phenomena in macroscopic objects," researcher Thiago Pedro Mayer Alegre explained.
"The point of developing the disk with this bullseye design was to prevent the mechanical mode from 'seeing' the central pedestal that supports the disk and allow the entire structure to vibrate, eliminating mechanical losses.”
Potential applications include force and motion sensors, and optical modulators in telecommunications. The device could be used as an optical switch and the researchers claim could work far more efficiently than the modulating technologies used today in optical telecommunications networks.
