This paper reports the light emission from aligned multiwalled carbon nanotubes (MWNTs) under continuous wave CO_2 laser (lambda = 10.6 mu m) irradiation. Results indicate that the light emission is dependent on the angle theta between the laser incident direction and the nanotube axis. The relative intensity of the light emission at certain wavelengths shows a Lorentzian feature when theta varies from 0 deg to 90 deg. The Lorentzian fitting curve displays a distinct tendency between shorter (lambda < 600 nm) and longer wavelength (lambda > 700 nm). A minimum intensity was observed at theta_m close to 67 deg under shorter wavelength, whereas a maximum intensity was shown at theta_m of about 60 deg at longer wavelength. These results show the anisotropic property of aligned MWNTs.
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