Enhancing microbolometer performance at terahertz frequencies with metamaterial absorbers
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Authors
Kearney, Brian T.
Subjects
Terahertz
Metamaterial
Perfect Absorber
Microbolometer
Thermal Imager
Bimaterial Sensor
Thin Film Absorber
Metamaterial
Perfect Absorber
Microbolometer
Thermal Imager
Bimaterial Sensor
Thin Film Absorber
Advisors
Karunasiri, Gamani
Date of Issue
2013-09
Date
Sep-13
Publisher
Monterey, California: Naval Postgraduate School
Language
Abstract
For Terahertz (THz) imaging to be useful outside of a laboratory setting, inexpensive yet sensitive detectors such as uncooled microbolometers will be required. Metamaterials can improve THz absorption without significantly increasing the thermal mass or using exotic materials because their absorption is primarily dependent on the geometry of the materials and not their individual optical properties. Finite Element (FE) simulations revealed that an array of squares above a ground plane separated by a dielectric is efficient, yet thin. Metamaterials were fabricated and their absorption characteristics were measured using a Fourier Transform Infrared Spectrometer (FTIR) indicating that the FE simulations are accurate. Metamaterial structures tuned to a quantum cascade laser (QCL) illuminator were incorporated into a bi-material sensor, which was used for detection of THz radiation from the QCL source with good sensitivity. In the case of microbolometers, a bolometric layer needs to be embedded in the metamaterial to form a thin microbridge. Simulations indicated that if the bolometric layer was resistive enough or close enough to the ground plane, then absorption would be largely unaltered. Metamaterials with a conductive Titanium (Ti) layer embedded into the dielectric spacer were fabricated and measured with an FTIR, confirming this behavior.
Type
Thesis
Description
Series/Report No
Department
Physics
Organization
Identifiers
NPS Report Number
Sponsors
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Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.