Nonlinear optical property of aligned multi-walled carbon nanotube film

the nonlinear optical properties of aligned multiwalled carbon nanotubes (MWCNTS) are studied. Measured photoluminescence spectrum of MWCNTs film reveals that there are two emission peaks at 450 nm and 470 nm while MWCNTs are excited by 675 nm photons and 704 nm photons respectively. The MWCNTs absorption spectrum indicated that there are a peak point at 450 nm and a valley bottom at 470 nm. An energy model was proposed to explain the MWCNT multi-photon absorption reasonably: Three-photon absorption of 675 nm photons would lead to 450 nm photons emission while two-photon absorption of 704 nm would excite 470 nm photons.