The elimination of the F-P effect in terahertz signals from a parameter-optimized decomposition

An improved variational modal decomposition method is proposed in this study which selects the penalty factor and decomposition number of the variational modal decomposition based on particle swarm optimization algorithm. After separating the real and imaginary parts of the spectrum, the standard deviations of the real and imaginary parts of the modal envelope are calculated. The mean of standard deviation is used as the adaptive threshold. This method can eliminate the F-P effect better than the traditional filtering method. Therefore, this method is more suitable for extracting the optical parameters of different materials and provides a new idea for terahertz signal preprocessing.