Exciton-radiation interaction in nanostructures

New aspects of exciton-radiation interaction are discussed from the viewpoi nt of microscopic nonlocal optical response developed for the study of nano -structure materials. Emphasis is put on (a) radiative width as a general m easure of coupling strength, by which various mechanisms of enhancement and suppression of the coupling strength are discussed for a wide variety of ( size, shape and arrangement) of a sample, (b) the effect of LT (longitudina l-transverse) splitting on the excitons in a quantum dot, and (c) the spati al structure of resonant light and its size-resonant enhancement, which lea ds to a remarkable new type of nonlinear processes with a doubly resonant e nhancement effect. (C) 2000 Elsevier Science B.V. All rights reserved.