Manipulation of nonlinear optical response via nanoscale spatial structure of resonant internal field

By means of nonlocal theory, a peculiar signal enhancement is discussed for the nonlinear response due to resonant behavior of a particular spatial pattern of the internal field in an ultrathin film. Also, a theory of transient nonlinear pulse response of confined excitons is presented, and a numerical result is demonstrated for a particular model. The microscopic variation of the internal electromagnetic field is fully treated in this method, and a nanoscale spatial variation of the internal field in an ultrathin film is found even in the response to a very short pulse.