Researchers Learn From Whispering Galleries To Develop Optomechanical Sensors

Researchers Learn from Whispering Galleries to Develop Optomechanical Sensors

11 June 2013

You have likely heard of whispering galleries and probably you have already been in one - a quiet, circular space, often beneath a dome or a vault, in which whispers can be heard clearly in any other part of the gallery. It might seem odd, but similar principles can work well for developing optomechanical sensors, R&D Magazine reports. This is at least what researchers at the University of Illinois at Urbana-Champaign and the University of Michigan are trying to accomplish in their attempt to find out more about the different vibration motions of chemical and biological samples at the nanoscale.

Gaurav Bahl, an assistant professor of mechanical science and engineering at the University of Illinois, describes optomechanics as an area of research in which forces exerted by light are used to produce and control high-frequency mechanical vibrations of microscale and nanoscale devices. The researcher explained that when applied in glass microcavities designed to imitate a whisper gallery, these miniscule optical forces can be aggravated by many orders-of-magnitude, which makes the "conversation" between light (photons) and vibration (phonons) possible.

For the purposes of their experiment, the research team used fused silica glass to create a hollow optomechanical device to infuse fluids and gases. Thanks to an innovative optomechanical interaction called Brillouin Optomechanics, the experiment resulted in the optical excitation of mechanical whispering-gallery modes at an impressive range of frequencies of between 2 MHz and 11,000 MHz.

"These mechanical vibrations can, in turn, 'talk' to liquids within the hollow device and provide optical readout of the mechanical properties," Bahl explained. By directing a broad range of fluids inside inside a hollow microfluidic optomechanical (?FOM) resonator, the team created the first bridge between optomechanics and microfluidics ever built.

The technology can be used in optomechanical biosensors to analyze the optical and mechanical properties of cells, fluids and fluid flow control.