Megahertz‐Rate Widely Tunable Fiber Filters Enabled by LiNbO3 Actuators

Abstract High‐speed optical fiber tunable filters are crucial for wavelength sweeping and spectral analysis, but reliably capturing transient events in submicrosecond‐scale, such as blasting and seismic waves, remains a challenge. Conventional piezoelectric transducer (PZT) typically achieves tuning rates of 10 kHz level due to its relatively low mechanical quality factor (Q factor) and high dielectric loss, limiting its performance in high‐speed applications. Here a fast‐tuned, large‐range filter is demonstrated by integrating a fiber Fabry‐Perot (FP) cavity onto a multilayer all‐lithium niobate (LiNbO 3 , Y‐cut 163‐degree) actuating structure. Leveraging the low dielectric loss, high electromechanical coupling coefficients (EMCC) and mechanical Q factor of LiNbO 3 , along with the lightweight integration optimization, a high tuning frequency of ≈1.52 MHz and a tuning range of ≈20 nm are achieved, while maintaining high filtering fineness and low optical loss. The device's overall performance, particularly its loaded tuning frequency, represents a significant improvement over previously reported works. The alignment‐free, non‐adhesive assembly approach of device produces stable response, effectively eliminates the need for hysteresis compensation, enabling highly accurate, submicrosecond‐scale spectra monitoring in fiber demodulation systems. This study presents a competitive solution for high‐speed demodulation and is essential for advancing fiber sensing technologies in applications involving transient event measurements.