橋本 研也

This paper describes the coaxial integration of a Michelson interferometer (MI) and a Sagnac interferometer (SI) in a high-speed, phase-sensitive laser probe for surface acoustic wave/bulk acoustic wave devices. This combination enables the MI to be used for calibration of the vibration amplitude captured by the SI without sacrificing the measurement accuracy and speed of the SI-based laser probe. First, the system setup is detailed. Next, simultaneous measurement is performed using the SI and MI, and good coincidence is demonstrated between these measured results after correction of tiny misalignment between two optical axes. This means that the calibration can be performed simply by multiplying the data captured by SI by a coefficient of proportionality this value of this can be determined by comparison with the data captured by simultaneous measurement for a tiny area. Finally, the procedure for absolute vibration amplitude measurement is proposed and its validity is confirmed by actual measurement.

This paper proposes a detection electronics which enables ultimate suppression of leakage signals in high-speed and phase-sensitive laser probe for radio frequency surface and bulk acoustic wave devices. Another merit is simpler circuit configuration than the conventional one. First, the complete suppression of leakage signals is verified. Then impact of the oscillator phase noise is examined by utilizing oscillators with various phase noise performance. This is because the proposed electronics is expected to be more sensitive to the oscillator phase noise than the conventional one. The result indicates that although performance degradation appears, it is practically negligible. In this electronics, the absolute phase can not be determined. This is not a demerit for use in the laser probe because additional phase shift caused by cables and printed circuit board is hard to calibrate.

This article describes derivation of an equivalent circuit for nonlinear responses in film bulk acoustic resonators from the first-order perturbation analysis using the piezoelectric constitutive equations with the h-form. For simplicity, electrodes and piezoelectric layers are considered as mass and spring, respectively, in the derivation. Then, it is demonstrated that the second-and third-order harmonic responses can be simulated well by the circuit. In addition, nonlinearity in the Si substrate is also taken into account and its impact is discussed. It is also discussed how the frequency dependences vary with the nonlinearity mechanisms as a finding from the derived equivalent circuit.