Thermo-optomechanical oscillations in high-Q ZBLAN microspheres.

We report stable thermo-optomechanical oscillations in high-Q-spherical ZBLAN microcavities. The oscillations are manifested as a complex combination of fast and slow oscillation periods. This behavior appears to be a consequence of the interplay between the negative thermo-optic effect, thermal expansion, and the Kerr effect. We have characterized the oscillatory behavior and measured the corresponding frequencies as a function of input power, wavelength detuning, and loaded optical quality factor. Our analysis shows that, as a gas sensor in the mid-IR spectral region, this thermo-optomechanical oscillator is two orders of magnitude more sensitive than previously demonstrated hybrid microtoroidal oscillators operating in the near-IR spectral region.