Autoparametric optical drive for micromechanical oscillators

Self-generated vibration of a disk-shaped, single-crystal silicon micromech anical oscillator was observed when the power of a continuous wave laser, f ocused on the periphery of the disk exceeded a threshold of a few hundred m uW. With the laser power set to just below the self-generation threshold, t he quality factor for driven oscillations increases by an order of magnitud e from Q=10 000 to Q(enh)=110 000. Laser heating-induced thermal stress mod ulates the effective spring constant via the motion of the disk within the interference pattern of incident and reflected laser beams and provides a m echanism for parametric amplification and self-excitation. Light sources of different wavelengths facilitate both amplification and damping. (C) 2001 American Institute of Physics.