Nonlinear optical materials of polypeptides

A nonlinear optical material comprising a composition consisting essentially of (a) 50-91% weight of a polypeptide, said polypeptide being a homopolymer of an amino acid or a copolymer of two or more amino acids, said amino acid or acids selected from alanine, aminoadipic acid, aminobutyric acid, aminocaproic acid, aminocyclohexanoic acid, aminovaleric acid, aminomalonic acid, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glycine, histidine, homocysteine, isoleucine, leucine, lysine, methionine, norvaline, ornithine, phenylalanine, serine, threonine, tyrosine, valine, and proline;

• and (b) 1-50% by weight of a compound exerting a non-linear optical response, said compound having a secondary molecular susceptibility larger than 1.times.10.sup.-30 esu and being selected from the group consisting of urea derivatives, enone derivatives, nitroaniline derivatives, heterocyclic compounds, stilben derivatives and merocyanines, wherein said urea derivative is ##STR8## said enone derivative is ##STR9## said nitroaniline derivative is ##STR10## said heterocyclic compound is ##STR11## said stilben derivative is ##STR12## wherein Me=a methyl group and
• * =an optically active carbon.