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Abstract
Photonic crystals (PhCs) are envisioned as the semiconductors for photonics technology and are believed to be the key materials/platforms for photonic integration. The development of PhCs has enabled groundbreaking approaches to mold the flow of electromagnetic waves with frequency spanning from RF regime to optical domain. The applications of PhCs fall into two categories: bandgap-engineering and dispersion-engineering. Research presented in this dissertation focuses on the novel dispersion properties and some of the first-ever applications of dispersion-engineered PhCs. By engineering the dispersion of a 2D PhC, a flat cylindrical lens was designed and fabricated, through which 2D negative refraction and 2D subwavelength imaging were experimentally demonstrated in both amplitude and phase. The results achieved in the 2D structure provided the principal insights into negative refraction. Further effort was then focused on materials exhibiting full 3D negative refraction due to their practical applications and theoretical interests in them. Full 3D negative refraction and 3D subwavelength imaging were then experimentally achieved by engineering the dispersion of a 3D body-centered cubic PhC. Negative refraction flat lenses provided super-resolution and curvature-free imaging, which can find potential applications in improving the performance of optical tweezers and allows the construction of an optical tweezers array with a single negative refraction flat lens. To this end, microwave electromagnetic trapping and manipulation of neutral particles were experimentally realized using the full 3D negative-refraction flat lens.
In addition to negative refraction, self-collimation of electromagnetic waves in 2D and 3D PhCs was also theoretically investigated and experimentally demonstrated. Self-collimation of electromagnetic waves was numerically simulated and experimentally observed even in low-index-contrast 2D PhCs. Furthermore, self-collimation was also achieved in a 3D PhC by engineering the dispersion property of a simple cubic PhC. Self-collimation allows for creating "non-diffractive materials", in which light can propagate without divergence while no specific route is introduced. The potential applications of this novel effect include high-density optical interconnection with low optical-channel crosstalk. By combining a novel fiber-to-chip interconnect technique which we developed, a framework is provided to realize chip-to-chip and on-chip optical interconnects. The uniqueness of this research is that dispersion properties of both 2D and 3D PhCs are explored, and experimental device characterization is demonstrated in both amplitude and phase. Although a large part of the research was carried out in the millimeter-wave regime, the demonstration of negative refraction imaging at near infrared frequencies also verified that all the dispersion-engineered PhC devices can potentially be scaled to nanometer dimensions for applications in the optical regime.*
*This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Windows MediaPlayer or RealPlayer.
