Investigating the relationship between composite multiscale entropy and optical property of bovine serum albumin solutions using THz pulsed system

•A linear behavior between CMSE and absorption coefficient or refractive index of BSA aqueous solutions is achieved preliminarily.•VMD is introduced into decompose THz signals into several mode functions with different frequency components.•A methodology of using VMD-CMSE for extracting optical features of the THz signals has been established.