Electrical and Computer Engineering ETDs

Publication Date

8-31-2011

Abstract

The use of optics to detect ultra-subwavelength features embedded within structures is a hot topic for a broad diversity of applications like spectroscopy, nanotechnology, microscopy, and optical data storage discs. Conventional objective lens based optical systems have a fundamental limit on the best possible resolution of about 200 \u03b7m due to the diffraction of light as it propagates into the far-field. There already exist several near-field techniques with the capability to overcome this limitation, but each of these systems has certain drawbacks related to the complexity of the system or to limitations imposed by the system. A photonic nanojet is a very particular beam of light that can provide a practical way to overcome the diffraction limit inherent to far-field techniques. A nanojet is an electromagnetic field envelope formed on the shadow-side surface of a plane-wave-illuminated dielectric microsphere of diameter larger than the wavelength and with refractive index contrast relative to the background medium of less than 2:1. It can maintain a subwavelength transversal beamwidth for distances greater than 2 wavelengths away from the surface of the generating microsphere. This Dissertation provides a computational test of the hypothesis that the backscattered spectrum resulting from photonic nanojet illumination of a three-dimensional (3-D) dielectric structure can reveal the presence and location of ultra-subwavelength, nanoscale-thin weakly contrasting dielectric inhomogeneities within dielectric targets. The effect of surface roughness on the illuminated side of the target is analyzed, and targets ranging from simple dielectric slabs to complex biological cells are studied. The present work is performed through computational electrodynamics modeling based upon the rigorous, large-scale solution of Maxwells equations. Specifically, the 3-D finite-difference time-domain (FDTD) method is employed to test the above hypothesis.'

Keywords

Nanophotonics., Holographic interferometry.

Sponsors

Consejo Nacional de Ciencia y Tecnología, National Science Foundation Smart Lighting Engineering Research Center

Document Type

Dissertation

Language

English

Degree Name

Electrical Engineering

Level of Degree

Doctoral

Department Name

Electrical and Computer Engineering

First Committee Member (Chair)

Christodoulou, Christos

Second Committee Member

Taflove, Allen

Third Committee Member

Han, Sang

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