Fig. 1. VMD IMF spectrum during over-decomposition

Fig. 2. Algorithm flow chart

Fig. 3. Construction of optical down-conversion system

Fig. 4. Optical down-conversion system output when no signal is detected

Fig. 5. Optical down-conversion system output when three types of signals are detected

Fig. 6. Spectrum of all over decomposed IMFs

Fig. 7. Spectral segmentation factor between over decomposed IMFs

Fig. 8. Optical down-conversion signal separated by the method proposed in this article