  We report studies of optical Fabry-Perot microcavities based on
semiconducting single-wall carbon nanotubes with a quality factor of 160. We
experimentally demonstrate a huge photoluminescence signal enhancement by a
factor of 30 in comparison with the identical film and by a factor of 180 if
compared with a thin film containing non-purified (8,7) nanotubes. Futhermore,
the spectral full-width at half-maximum of the photo-induced emission is
reduced down to 8 nm with very good directivity at a wavelength of about 1.3
$\mu$m. Such results prove the great potential of carbon nanotubes for photonic
applications.
