Spectral Decomposition of Aberrated Wavefronts from Actuated Micromirrors

Aberrated optics degrade the cavity finesse and point spread function of any optical system. It is frequently overlooked that the phase errors of these aberrations cause characteristic spectral features that can be observed and measured by an optical cavity. A general theory of the spectral decomposition of aberrations is developed and applied to an electrically deformable membrane feeding a high-finesse resonator. The micromirror, which consists of a 1 cm metallized SiN
_x
electrostatically-actuated membrane with phase offsets of about 1.5μm, leads to optical power being distributed to over twenty higher-order Laguerre-Gaussian cavity modes.