Sign-alternating optical reorientation in nematic liquid crystals with low-molar-mass and polymeric absorbing bis-azobenzene dopants

•Incorporation of bis-azobenzene monomer into the polymeric chain increases the sign-alternating nonlinearity of an NLC.•After incorporation the orientational nonlinearity increases in both positive and negative regions.•Critical angle of the sign-alternating nonlinearity decreases for polymeric molecule.•Passage from the low- to the high-molar-mass dopant increases enhancement factors related to trans- and cis-isomers.