Problems in Scattering and Imaging

Abstract:

In this work, we explore a broad spectrum of topics associated with the problems of scattering and imaging. The first direction concerns the fundamental study of the symmetry breaking and the nonlinear light scattering in the system of gold nanorod. A microscopic model was developed where the second order longitudinal plasmon resonance mode scatters with the electron gas and the plasmon damping effect is accounted for. The new description simultaneously and quantitatively explains all the main features of the nonlinear optical components.

In the second direction, we demonstrate an optical system that enables the control of monochromatic light transmission through highly scattering media, with Complex Semi-DeInite Programming (SDP) introduced as a novel approach to solve the associated phase retrieval problem. In contrast to the conventional approach that employed the interferometric design, a simple optical setup without need for a reference beam is proposed.

In the third direction, the optical properties and applications of graphene were explored. In the first part, we focus on the absorption saturation in optically excited graphene. The microscopic theory that includes Coulomb-scattering as the dominant relaxation mechanism at high carrier densities was verified by the optical transmission experiment. In the second part, a novel scheme of light field camera using focal stack was proposed. The prototype single-pixel light field camera was built and demonstrated in the optical experiment. The framework for the model-based light field reconstruction was provided, with the system design based on the Fourier slice analysis.