▎ 摘　　要

The third-order optical nonlinearities, characterized by the second-order hyperpolarizabilities gamma, of chiral graphene tubules are studied. The average contribution eta of one carbon atom to the third-order optical nonlinearity of each chiral graphene tubule is calculated and compared with that of a well characterized polyenic polymer. It is found that the smaller the diameter of a chiral graphene tubule, the larger the average contribution eta; the metallic chiral graphene tubule favors larger gamma values; chiral graphene tubules can compete with the conducting polymer achieving a large gamma value which is needed for photonic applications. (C) 1999 Elsevier Science B.V. All rights reserved.