Two Dimensional Laser Probe for detection of Longitudinal Wave Vibration in GHz Range

研制了一种用于射频体声波器件诊断的相敏快速扫描激光探针系统。该系统是基于Sagnac干涉仪，这是不敏感的低频振动。我们还开发了一种新的自动聚焦系统，用于解决当样品表面不平坦和/或倾斜时出现的散焦问题，并采用高放大率透镜。实验结果表明，对于工作在2GHz频段的高频体声波器件，采用100倍透镜，可以在几分钟内获得高质量的振动场二维图像。对测量数据进行了波数域分析，揭示了能量泄漏在器件中发生的方式和位置。

The authors developed a phase-sensitive and fast- scanning laser probing system for the diagnosis of radio frequency (RF) bulk acoustic wave (BAW) devices. The system is based on the Sagnac interferometer, which is insensitive to low frequency vibration. We also developed a new auto-focusing system for solving the defocusing problem arisen when the specimen surface is uneven and/or canted and a high magnification lens is employed. It was demonstrated that high quality two-dimensional (2D) image of vibration field patterns can be captured in minutes order for RF BAW devices operating in 2GHz range with 100x lens. The wavenumber domain analysis was also applied for the measurement data, and it was revealed how and where the energy leakage occurs in the device under concern.