In this work, we report on second order nonlinear optical (NLO) susceptibilities of some substituted 4-(5-nitro-1,3-benzoxazol-2-yl)aniline chromophores that were embedded into photopolymer matrices. Depending on the photo-induced nitrogen laser (wavelength 371 nm) power density of photo-solidification we found an optimal photo-solidification parameter to achieve maximum second harmonic generation (SHG). The influence of the π-conjugated bonds on the output second order susceptibility and HOMO-LUMO level positions is analysed. The performed experiments are compared with the theoretically calculated microscopic hyper-polarizabilities obtained within the B3LYP DFT approach. The possible operation by the output SHG efficiency versus the photoinduced laser power density is presented. The role of the intra-molecular and surrounding polymers in the observed nonlinear optical behaviour is explored.