  Nanotube-based systems are good candidates for optical limiting against
broadband laser pulses. We explore new routes to improve their limiting
performances. We show that the diameter of the nanotubes is a key factor to
control the performances. On the other hand, we demonstrate that chemically
modified nanotubes can be mixed with organic chromophores, leading to high
performance composite limiting systems which are particularly efficient in the
nanosecond regime due to the cumulative effects of nonlinear scattering and
multiphoton absorption.
