Generation and detection of circularly-polarized (CP) radiation in the 8- to 12-μm band of the infrared (IR) spectrum is crucial for polarization sensing and imaging scenarios. There is very little naturally occurring CP radiation in the long-wave IR band, so that useful functionalities may be obtained by exploiting preferential radiation and transmission characteristics of engineered metamaterials. Conventional CP devices in the IR utilize birefringent crystals, which are typically bulky and expensive to manufacture. The operation of these devices is generally optimized at a single wavelength. Imaging in the long-wave IR is most often broadband, so that achromatic CP-device behavior is highly desirable from a fluxtransfer viewpoint. Also, size, weight and cost are significant drivers in the design of practical IR systems. Thus a solution is sought with a convenient thin planar form factor. This dissertation will demonstrate a novel planar periodic subwavelength-microstructured approach derived from classical radiofrequency meanderline designs that are able to generate CP radiation over a broad IR band while maintaining a low fabrication profile. We investigate issues regarding efficiency as a function of the number of layers in the device structure; reflective, transmissive, and emissive behavior; strategies for broadband achromatization; and thermal-isolation requirements between the active blackbody reservoir and the top of the planar device, to achieve a given degree of polarization. Theoretical, numerical, and experimental findings are presented that confirm the feasibility of this class of devices for use in a wide variety of situations, from polarization imaging and spectroscopy to industrial laser processing and machining.
| Identifer | oai:union.ndltd.org:ucf.edu/oai:stars.library.ucf.edu:etd-2810 |
| Date | 01 January 2011 |
| Creators | Wadsworth, Samuel Lanning |
| Publisher | STARS |
| Source Sets | University of Central Florida |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Electronic Theses and Dissertations |
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