Theoretical estimations of third-order optical nonlinearities for semiconductor carbon nanotubes

摘要: In this study we present theoretical predictions concerning the third-order nonlinear optical properties of semiconductor carbon nanotubes for photon energies well below fundamental absorption edge. Both virtual interband -electron transitions and combined intraband-interband ones are assumed to be basic microscopic mechanisms nonlinearities in spectral region. Resting upon simple dimensional considerations using only model-independent energy spectrum near conduction- valence-band edges, obtain estimations low-frequency susceptibility due these two mechanisms, which sheds light on relationship between non-resonant response their geometrical electronic structure. This result derived physically interpretable terms is good agreement with that obtained our recent basis a systematic analytical approach. We find single-shell `zig-zag' display positive values, contribution from dominating negative purely transitions. also increase nanotube radius R results strong enhancement , can reach values larger by several orders magnitude than those reported fullerene molecules . draw conclusion modification structure provides an efficient means engineering novel nonlinear-optical materials high cubic susceptibilities.