Individual single-wall carbon nanotubes (SWNTs) exhibited continuous-wave stimulated Raman scattering (SRS). The Raman gain is a few orders higher, and the threshold power is a few orders lower, than values ever reported for other bulk materials and is explained as the result of both the large nonlinear property and efficient electron-phonon interaction in the SWNT. The laser-induced variation of the peak position of the SRS line was likely to depend on the linewidth or tube quality. The results demonstrate the high potential of SWNTs in applications of nanoscale nonlinear optical devices such as wide-range tuneable Raman lasers.
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Due to the one-dimensional quantum wire shape of a SWNT, the movement of electrons is strictly restricted along the tube axis. Therefore, the interaction length is in the same order as that of the tube length.