Autoparametric optical drive for micromechanical oscillators

Abstract

Self-generated vibration of a disk-shaped, single-crystal silicon micromechanical oscillator was observed when the power of a continuous wave laser, focused on the periphery of the disk exceeded a threshold of a few hundred μW. With the laser power set to just below the self-generation threshold, the quality factor for driven oscillations increases by an order of magnitude from $\text{Q=10\hspace{0.05em}000}$ to $Q_{\mathrm{enh}}\text{=110\hspace{0.05em}000.}$ Laser heating-induced thermal stress modulates the effective spring constant via the motion of the disk within the interference pattern of incident and reflected laser beams and provides a mechanism for parametric amplification and self-excitation. Light sources of different wavelengths facilitate both amplification and damping.