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Reconfigurable Holographic Fabrication of Moiré Photonic Crystals and Their Optical PropertiesHurley, Noah Benjamin 12 1900 (has links)
Moiré photonic crystal is an optical analog of twisted graphene. Photonic crystals are a material made up of periodic index material which allow for the manipulation of light. The interference of diffracted beams from a spatial light modulator allow for the creation of photonic crystals via a process named holographic lithography where nine beams (four inner beams + four outer beams + central beam) are overlapped. By modifying the phase and amplitude of the interfering beams, the interference patterns of 3D moiré photonic crystals are systemically simulated and compared with the holographic structures to gain a comprehensive understanding of SLM-based holographic fabrication. Diffraction zones generated and are seen as 5 × 5 non-uniform diffraction zones. The diffraction zone pattern demonstrates a characterization method for the fabricated 3D moiré photonic crystals.
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Optical Property Study of 2D Graded Photonic Super-Crystals for Photon ManagementHassan, Safaa 05 1900 (has links)
In this dissertation, we study the optical property of 2D graded photonic super-crystals (GPSCs) for photon management. We focused primarily on manipulation and control of light by using the newly discovered GPSCs which present great opportunity for electromagnetic wave control in photonic devices. The GPSC has been used to explore the superior capability of improving the light extraction efficiency of OLEDs. The enhancement of extraction efficiency has been explained in term of destructive interference of surface plasmon resonance and out-coupling of surface plasmon through phase matching provided by GPSC and verified by e-field intensity distributions. A large light extraction efficiency up to 75% into glass substrate has been predicted through simulation. We also study the light trapping enhancement in GPSCs. Broadband, wide incident angle, and polarization independent light trapping enhancement is achieved in silicon solar cells patterned with the GPSCs. In addition, novel 2D GPSCs were fabricated using holographic lithography through the interference lithography by two sets of multiple beams arranged in a cone geometry using a spatial light modulator (SLM). Finally, we also report a fabrication of GPSCs with a super-cell size of 12a×12a by using e-beam lithography. Diffraction pattern from GPSCs reveals unique diffraction properties. In an application aspect, light emitting diode arrays can be replaced by a single light emitting diode shinning onto the diffraction pattern for a uniform fluorescence.
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