Alq3 coated silicon nanomembranes for cavity optomechanics

The optomechanical properties of a silicon-nitride membrane mirror covered by Alq3 and Silver layers are investigated. Excitation at two laser wavelengths, 780 and 405 nm, corresponding to different absorptions of the multilayer, is examined. Such dual driving will lead to a more flexible optomechanical operation. Topographic reconstruction of the whole static membrane deformation and cooling of the membrane oscillations are reported. The cooling, observed for blue laser detuning and produced by bolometric forces, is deduced from the optomechanical damping of the membrane eigenfrequency. We determine the presence of different contributions to the photothermal response of the membrane.