High-order harmonic generation by conduction electrons in carbon nanotube ropes - art. no. 053808

High-order harmonic generation by metallic carbon nanotubes exposed to an i ntense ultrashort pulse has been theoretically investigated in the semiclas sical approximation. The mechanism of nonlinearity provided by the motion o f pi electrons has been considered. It has been shown that the high density of conduction electrons in metallic carbon nanotubes and the specific disp ersion law inherent in hexagonal crystalline structure result in the effici ent generation of high-order harmonics with intensities that fall down smoo thly with harmonic number, without cutoff, and with efficiency much larger than in gases with the same pump intensity. We have also studied phase matc hing for different harmonics in a lope of parallel-aligned carbon nanotubes dependent on the angle of incidence.