In the ongoing quest to trap the light fantastic, a group of researchers from the University of Campinas, Brazil have developed what they are calling a new type of optomechanical device that relies on a microscopic silicon disk to confine optical and mechanical waves. According to the research team, the device is customizable and compatible with commercial manufacturing processes. As a result, it may prove highly viable for improving sensors that detect force and movement.
Optomechanical devices use light to detect movement and designers are constantly working to make them smaller and more sensitive. Identifying the smallest movements requires extremely high levels of interaction, or coupling, between light waves, which are used for detection and the mechanical waves that are tied to movement. The researchers claim their bullseye disk achieves coupling rates that match those of the best existing lab-based optomechanical devices.
The bullseye disk device is fabricated in a standard commercial foundry with the same processes used to manufacture complementary metal-oxide-semiconductor (CMOS) chips.That means, according to research-group leader Thiago P. Mayer Alegre, any manufacturer in the world could reproduce it and it would perform in the same manner. Reportedly, it is also much cheaper and faster to make these types of devices at a CMOS foundry rather than using specialized in-house fabrication techniques.
The researchers created a silicon disk 24 microns wide that confines light and mechanical waves using separate mechanisms. Light is confined with total internal reflection, which causes the light to bounce off the edge of the disk and travel around the outer portion in a circular ring. Circular groves in the disc create the appearance of a bullseye to localize mechanical motion to the outer ring, where it can interact with the light and a central pedestal supports the disk, allowing it to move as required.
The researchers are refining the device to lessen the amount of light lost by the disk and improve overall performance. They also want to make the device even more practical by combining the optomechanical disk with an integrated optical waveguide that would bring light to and from the device, all in one package.
A technical paper written by the researchers, F.G.S. Santos, Y.A.V. Espinel, G.O. Luiz, R.S. Benevides, G.S. Wiederhecker, and T.P.M. Alegre, titled “Hybrid confinement of optical and mechanical modes in a bullseye optomechanical resonator,” is available.