Resonant grating structures: Theory, design, and applications

This thesis explores the theory, design, fabrication, and applications of resonant grating filters. A resonant grating structure is a diffractive device that strives to enhance a particular type of grating anomaly, the resonance anomaly. The resonance anomaly is characterized by a sharp reflection or transmission peak over wavelength or angle, thus making it suitable for filtering applications. Indeed, the narrow bandpass of this filter can be applied to other applications such as modulators, polarization components, security devices, and chemical and biosensors.; Toward the development of design principles that can be applied to these structures, an approximate coupled-mode theory approach is developed that allows the resonant width in angle and wavelength to be calculated directly, without the need to profile the reflectivity response of the resonance using cumbersome rigorous diffraction algorithms. To verify the results of these calculations, a homogeneous rigorous model is developed from the inhomogeneous modal analysis method as well as the rigorous coupled-wave method. It is found that the coupled-mode approach, a computationally efficient method, agrees well with the results obtained from the rigorous diffraction calculations. While there are some regimes where the approximation can fail, these are well understood and described in detail.; Fabrication of resonant grating structures for the visible portion of the spectrum is still a challenge. Two different methods for the grating exposure fabrication steps are explored--holographic exposure and e-beam lithography. The goal in fabrication is to achieve the highest peak reflection efficiency from a particular resonant grating structure. The single most important impediment to obtaining 100% efficiency is grating noise. To explore the issue of fabrication errors on resonant efficiency and to verify theoretically predicted trends in resonant linewidth versus a given structure parameter, a bare resonant grating was fabricated using e-beam lithography. The structure was immersed in different liquids to simulate different cover layer refractive indexes. Trends in resonant width and position as a function of angle and diffraction efficiency were compared to both approximate and rigorous methods.