Enhancing precision in dispersion measurements of chirped fiber Bragg gratings with wavelet-based denoising

A wavelet-based denoising method is proposed to improve the precision of group delay dispersion (GDD) measurements of chirped fiber Bragg gratings (CFBGs) in spectral interferometry. By analyzing the sparsity changes of wavelet detail coefficients, the optimal decomposition level and mother wavelet are determined. A hybrid thresholding strategy is introduced to effectively suppress noise. The proposed method achieves a reduction in GDD uncertainty and extends the available spectral range from 35 nm to 42 nm. It also maintains robust performance across a wide range of relative time delays, demonstrating strong potential for improving the accuracy and reliability of dispersion measurements in variable signal-to-noise ratio (SNR) conditions.