High Absorption per unit Thermal Mass Subwavelength Perforated Membrane as Uncooled Thermal Infrared Detector
2023-01
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
High Absorption per unit Thermal Mass Subwavelength Perforated Membrane as Uncooled Thermal Infrared Detector
Authors
Published Date
2023-01
Publisher
Type
Thesis or Dissertation
Abstract
In the first project, a theoretical and experimental investigation of photon diffusion is discussed in highly absorbing microscale graphite. A Nd:YAG continuous wave laser is used to heat the graphite samples with thicknesses of 40 µm and 100 µm. Optical intensities of 10 kW/cm^2 and 20 kW/cm^2 are used in laser heating. The graphite samples are heated to temperatures of thousands of kelvins within milliseconds, which are recorded by a 2-color, high-speed pyrometer. To compare the observed temperatures, the differential equation of heat conduction is solved across the samples with proper initial and boundary conditions. In addition to lattice vibrations, photon diffusion is incorporated into the analytical model of thermal conductivity for solving the heat equation. The numerical simulations showed close matching between experiment and theory only when including the photon diffusion equations and existing material properties data found in the previously published works with no fitting constants. The results indicate that the commonly overlooked mechanism of photon diffusion dominates the heat transfer of many microscale structures near their evaporation temperatures. In addition, the treatment explains the discrepancies between thermal conductivity measurements and theory that were previously described in the scientifc literature. In the second project, a subwavelength perforated metamaterial absorber is developed for a maximum absorption-to-thermal mass ratio to construct an uncooled thermal infrared (λ∼8−12 µm) detector operating at a time constant of ∼7.7 ms, faster than the video frame rates, with a noise equivalent temperature difference (NETD) of 4.5 mKand a detectivity of 3.8×10^9 cm√Hz/W. The designed metamaterial absorber consists of Ti, SiNx, and Ni nanoscale films with an overall fill factor of ∼28%, where subwavelength interference and Fabry Perot resonance induce an absorption per unit mass of approximately 1.3−27.6 times higher than the previously reported infrared absorbers.
We read out the fabricated detector optically via Mach Zehnder interferometer.
Description
University of Minnesota Ph.D. dissertation. January 2023. Major: Electrical/Computer Engineering. Advisor: Joseph John Talghader. 1 computer file (PDF); xii, 136 pages.
Related to
Replaces
License
Collections
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Das, Avijit. (2023). High Absorption per unit Thermal Mass Subwavelength Perforated Membrane as Uncooled Thermal Infrared Detector. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/253427.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.