Infrared Methods Applied to Photonic Crystal Device Development
Kilby, Gregory Robert
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Photonic crystal (PC) technology potentially offers lossless control of light propagation at a size scale near the order of the wavelength of light. The advantages and benefits of using such a technology in commercial devices are staggering. Yet, the commercial development of PC structures has been slow. Challenges associated with the repeatable fabrication and testing of structures has been identified as one cause of the slow development pace. To address these challenges, a development methodology that utilizes PC structures operating in the long-wavelength infrared is presented. One-dimensional PC structures, consisting of alternating regions of silicon and air are fabricated and characterized by measuring the transmittance or reflectance of the structure over the wavelength range from 5 쭠to 15 쭮 For the measurements, a model of the focused infrared beam is developed, tested and employed to characterize the structures. A novel measurement method, enabling the calculation of the single-angle plane-wave transmittances and reflectances from composite, multiple-angle transmittance and reflectance measurements, is formulated, tested and applied to PC structures. A new spectral characterization tool using a discretely tunable carbon-dioxide laser is presented and demonstrated. A measurement apparatus employing an FTIR microspectroscopy system is developed and measurements are recorded for the single-angle plane-wave characterization method. Single-angle plane-wave transmittances and reflectances calculated from composite multiple-angle measurements are shown to be in excellent agreement with theory. The results of this research are analyzed to identify the advantages and limitations of the long-wavelength infrared method.