Optomechanical cavity with a buckled mirror

We study an optomechanical cavity, in which a buckled suspended beam serves as a mirror. The mechanical resonance frequency of the beam obtains a minimum value near the buckling temperature. Contrary to the common case, in which self-excited oscillations of the suspended mirror are optically induced by injecting blue detuned laser light, in our case, self-excited oscillations are observed with red detuned light. These observations are attributed to a retarded thermal (i.e., bolometric) force acting on the buckled mirror in the inward direction (i.e., toward the other mirror). With relatively high laser power, other interesting effects are observed, including period doubling of self-excited oscillations and intermode coupling.