Frequency Response Range Extended Slope-Assisted BOTDA Using Randomized Sampling

We propose and demonstrate a slope-assisted Brillouin optical time-domain analysis (SA-BOTDA) sensor with an extended frequency response range enabled by randomized sampling. By employing variable sampling intervals and non-uniform discrete Fourier transform (NUDFT), the proposed scheme overcomes the inherent pulse round-trip time limitation in conventional systems, enabling vibration detection beyond the Nyquist frequency range. In proof-of-concept experiments, vibration signals up to 3.5 kHz were detected with both randomized and uniform sampling, confirming the feasibility of vibration detection within 5 kHz Nyquist frequency range. To verify the frequency range extension, up to 400 kHz simulated vibration signal is successfully detected by the proposed method, which is far beyond the 5 kHz theoretical limit of traditional approaches. The proposed method reconciles the trade-off between sensing range and frequency response, offering a simple solution for ultra-high frequency vibration sensing in limited frequency response range scenarios.