In the optical detection of ultrasound, resonators with high Q-factors are often used to maximize sensitivity. However, increasing the Q-factor of a resonator may reduce the linear range of the interrogation scheme, making it more susceptible to strong external perturbations and incapable of measuring strong acoustic signals. In this Letter, a passive-demodulation scheme for pulse interferometry was developed for high dynamic-range measurements. The passive scheme was based on an unbalanced Mach–Zehnder interferometer and a 90° optical hybrid, which was implemented in a dual-polarization all-fiber setup. We demonstrated the passive scheme for detecting ultrasound bursts with pressure levels for which the response of conventional, active interferometric techniques became nonlinear.

中文翻译：

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用于高动态范围超声检测的无源解调脉冲干涉仪

在超声的光学检测中，通常使用具有高Q因子的谐振器来最大化灵敏度。但是，增加谐振器的Q因子可能会减小询问方案的线性范围，使其更容易受到强烈的外部干扰，并且无法测量强烈的声信号。在这封信中，针对高动态范围测量开发了一种用于脉冲干涉测量的无源解调方案。无源方案基于不平衡的Mach-Zehnder干涉仪和90°光学混合器，这是在双偏振全光纤设置中实现的。我们展示了一种用于检测具有一定压力水平的超声脉冲的无源方案，对于该方法，传统的有源干涉测量技术的响应变为非线性。