Scientists demonstrated a strong coupling between light and high-frequency acoustic vibrations in a silica microresonator. The findings could pave the way for novel applications of light-sound coupling in technology development. Brillouin scattering, a well-known nonlinear phenomenon first described in the 1920s, is involved.
The ability to achieve a strong coupling of photons and high-frequency phonons in the anti-Stokes process may find use in sensing devices and communications. It has not been easy to achieve that strong-coupling regime. The British team started with a wise material selection. They created a resonator that can support two light modes, one at the lower pump frequency of 1550 nm and one at the higher anti-Stokes frequency.
They discovered a key signature of optomechanical coupling between pump photons and 11-GHz acoustic phonons in an optical resonator system. Using a heterodyne detection setup, the researchers assessed the resonator’s spectra at various pump powers. The light-sound coupling performance could be improved further by fine-tuning the cavity design and materials and conducting experiments at cryogenic temperatures. According to the researchers, these advancements “could provide a rich avenue for developing a suite of new technologies, including classical and quantum information-processing applications and sensors, and even provide a path for coherent X-band microwave-to-optical conversion.”