NONLINEAR-OPTICAL PROPERTIES OF ARMCHAIR NANOTUBE

The magnitude of the third-order nonlinear polarizability gamma of arm chair nanotube is theoretically studied. The calculated results for th e C-70 tube are consistent with those measured by Neher et al. [Opt. L ett. 17, 1491 (1992)]. The static and dynamical magnitudes of gamma ca n be greatly enhanced by increasing the carbon number. When the carbon number is big enough, the major dynamical response peaks with large g amma magnitudes are located at the optical frequency omega near the en ergy gap E-g (i.e., 3 omega similar to 3E(g)), and the highest peak ma gnitude is much larger than that of C-70, which is important in practi cal use. (C) 1997 American Institute of Physics.