Nonlinear near-field spectroscopy and microscopy of single excitons in a disordered quantum well

Summary form only given. We present data that moves beyond this paradigm by exploring both spectral/spatial correlations between eigenstates of a disordered quantum well and examining spatial properties of the eigenstate itself. Unlike earlier work which relied on spectral and spatial diffusion for signal, degenerate cw nonlinear spectroscopy is utilized as an ´absorption-like´ probe capable of mapping all of the optically active states of the system. Sensitive only to the local excitonic dipole, when coupled with the sub-wavelength resolution of a low temperature near-field scanning optical microscope (NSOM), this technique provides a spectral and spatial map of the local density of states of the disordered quantum well.