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A detection scheme for obtaining phase and absolute amplitude information of surface vibrations on microacoustic components using homodyne laser interferometry is described. The scheme does not require active stabilization of the optical path length of the interferometer. The detection setup is realized in a homodyne Michelson interferometer configuration, and selected measurements on a 374 MHz surface acoustic wave fan-shaped filter and two different piezoelectrically actuated micromechanical resonators are presented to demonstrate the performance of the instrument. With the current detection electronics, the interferometer is capable of detecting out-of-plane surface vibrations up to 2 GHz with a lateral resolution of better than 1 μm and with a minimum detectable vibration amplitude of ∼1 pm. [ABSTRACT FROM AUTHOR]

The ongoing rapid development of digital camera technology together with increasing computing power enabling fast image analysis has opened up possibilities to further advance the performance of full-field interferometry. We present a software-based stabilization method for stroboscopic homodyne full-field interferometry that enables phase sensitive absolute-amplitude measurements of surface vibrations in microelectromechanical devices. The reference signal for the stabilization is obtained from a freely selectable region in the acquired interference images, resulting in a compact interferometer design without the need for additional optical components for monitoring the operation point. The proposed stabilization method is implemented in an LED-based stroboscopic Michelson-type full-field interferometer. To demonstrate the performance of the setup, an out-of-plane vibration field at 12 MHz in a square-plate silicon resonator is characterized. The data analysis reveals that a minimum detectable amplitude of less than 30 pm is achieved in the measurement. These first results already demonstrate the potential of the software-stabilization concept and serve to advance the detection of low-amplitude surface vibrations with full-field interferometry. [2014-0355] [ABSTRACT FROM PUBLISHER]

We present an experimental study of the frequency scaling of the main, square-extensional mode in a piezoelectrically actuated plate resonator. The studied set consists of resonators of different plate sizes with identical anchors. The behavior of the square-extensional mode is analyzed using electrical impedance measurements and optical characterization of the mechanical vibration fields. The results reveal a detrimental anchor effect, where for certain plate sizes the square-extensional mode branch is split into two due to a coupled oscillation of the resonator plate and the anchors. [ABSTRACT FROM AUTHOR]

We present an experimental study of the nonlinear behavior of a square-extensional (SE) mode microelectromechanical resonator, actuated with a piezoelectric AlN thin film. The acoustic vibration fields of the device are characterized using laser probing. A nonlinear vibration behavior of the SE mode is observed above a drive power level of -10 dBm such that the vibration amplitude of the SE mode saturates and a rotational in-plane vibration mode is excited at a significantly lower frequency (0.725 MHz) than the SE mode (16.670 MHz). Interestingly, the measured ∼10 nm saturation amplitude of the SE mode is more than a decade below the amplitude value at which mechanical or electromechanical nonlinearities are estimated to become significant. [ABSTRACT FROM AUTHOR]