Date of Award

1-1-2010

Document Type

Campus Access Thesis

Department

Physics and Astronomy

Sub-Department

Physics

First Advisor

Timir Datta

Abstract

Geometrically decorated two-dimensional (2D) discrete surfaces can be more effective than conventional smooth reflectors in managing wave radiation. Constructive non‐specular wave scattering permits the scattering angle (β) to be other than twice that of incidence (α). This result in gross violations of the law of reflection, and significant fraction of the α, β phase space becomes accessible. A wide range of novel reflective behaviors ensues; including the phenomenon of negative reflection were energy transport remains on the same side of the normal. Also, at a critical incidence [αcrit = Cos-1(1-κ) or Cos-1(κ-1)] coherent superposition can force both the transmitted and reflected waves to graze the scattering surface (α = β) thus synergistically reinforcing the diffractive process in a behavior reminiscent of critical internal reflection of ray optics.

We experimentally demonstrate the concept with measurements on a one-dimensionally periodic system (grating) where the relation α = cos-1[Z(β, κ)] holds; Z is shown to be a function of the diffractive index parameter (κ) and the two angles α and β. Excellent agreement is found between experimental data and theory. Future applications include generalized zone plate optics, motionless heliostats, beam splitting, evasive and deceptive imaging and high precision metrology. The relevant 2D-surfaces or meta-materials (2DMM) require patterns equal to less than a few wavelengths deep hence are far convenient than their 3‐dimensional counterparts.

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