High-frequency optical fiber vibration sensing system for micro–nano displacement measurement

This paper presents a fiber Fabry-Perot (F-P) cavity-based method for high-frequency micro-nano vibration displacement sensing, which can be integrated for high-frequency acoustic atomic force measurement. The F-P cavity is formed between a flat-ended fiber and the device under test. A local linear operating region of a single F-P interference fringe, corresponding to a phase variation of approximately 2<i>π</i>/3, is exploited for displacement calibration and demodulation. A displacement sensitivity of 37.804 mV/µm, yielding a displacement resolution of 0.089<i>p</i><i>m</i>/√<i>H</i><i>z</i> is achieved. The experiments demonstrate that the proposed system can detect a displacement of 1.08 nm @ 72.5 MHz, which provides a critical dynamic displacement sensing capability for accurate force-distance curve analysis and high-frequency micro-nano force measurements.