EXCITON CONFINEMENT AND NONLOCAL NONLINEAR-OPTICAL RESPONSE OF ORGANIC QUANTUM-WELLS

The linear and nonlinear reflection spectra from a molecular quantum w ell with N layers are calculated using Green-function techniques. Exci ton quantization in the direction normal to the lattice plane results in the appearance of discrete resonances in the linear reflection, wit h the same N-independent peak heights, and different superradiant line widths. Nonlinear reflection measurements are ideal for probing states with a weak oscillator strength, provided their nonradiative damping is much smaller than the radiative decay rate. Size enhancement of chi (3) due to dipole-dipole interaction and radiative coupling between la yers is discussed.