Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Electrical and Computer Engineering

First Advisor's Name

John Volakis

First Advisor's Committee Title

Co-committee chair

Second Advisor's Name

Nezih Pala

Second Advisor's Committee Title

Co-committee chair

Third Advisor's Name

Elias Alwan

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Andres Tremante

Fourth Advisor's Committee Title

Committee member

Keywords

Millimeter-wave, passive, imaging, optical, up-conversion

Date of Defense

3-24-2023

Abstract

The scientific objective of this dissertation is to develop and advance a passive millimeter wave imaging system that has high-sensitivity to detect natural mm-wave radiation emissions at 94 GHz. Due to the unique capability of millimeter-wave radiation to penetrate atmospheric obscuration such as dust, fog, rain, as well as thin dielectrics, passive millimeter-wave imaging has a wealth of potential applications that have long been recognized. However, although millimeter-wave imaging systems have evolved and improved, they have not lived up to their potential, primarily due to limitations in sensor sensitivity, resolution, cost, and size. The goal of this interdisciplinary dissertation research is to introduce a novel passive millimeter wave imaging system that operates at 94 GHz, viz. at the low atmospheric absorption window. The proposed system makes use of an optical up conversion process that encodes the naturally emitted black body radiation onto an optical beam for imaging using standard NIR camera. We developed a unique design of a photonic integrated chip in the form of antenna integrated electro-optic modulator. The focus of this dissertation is mainly on the front-end of the system that dictates the overall performance. The back end v is based on existing commercial off-the shelf imaging optics components. The main components of an electro-optical modulator are sensing elements such as an antenna or electrodes, the active optical region, and the passive signal medium, viz the optical waveguide/fiber. Our design is an on-chip antenna integrated modulator that is ultra-sensitive and can readily accommodate interferometric passive millimeter wave imaging, where the sensing element is a millimeter wave antenna. For this purpose, we propose a unique design architecture and its associated microfabrication process using standard UV lithography. This unique design integrates a planar antenna directly onto the electro-optic modulator that promotes efficiency and compactness. The developed millimeter imaging system has improved sensitivity and spatial resolution while concurrently eliminating bulky millimeter wave lenses, normally used in “all electronic” traditional systems. The received millimeter signals from the interferometric sparse array are coded on an optical beam that is subsequently imaged using standard near-infrared lenses and electronics.

Identifier

FIDC011072

Available for download on Wednesday, April 23, 2025

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