Optical Heterodyne Microvibration Detection Based on All-Fiber Acousto-Optic Superlattice Modulation

We propose a configuration of optical heterodyne microvibration detection based on an all-fiber acousto-optic superlattice modulation structure that acts as both frequency shifter and reflector, simultaneously. The vibration information within the frequency range between 1 Hz and 150 kHz of a piezoelectric mirror has been experimentally measured by using this all-fiber optical heterodyne detection configuration. The minimal measurable vibration amplitude and the resolution are around 0.013 nm and 10 pm in the region of tens to hundreds of kilohertz, respectively. The configuration not only has advantages of compact size, easy alignment, and noncontact measurement, but also gains high accuracy, which provides a promising alternative and could be applied in the compact and portable instruments based on optical heterodyne detection.