Incorporation of Nonconventional Crystalline Materials onto the Integrated Photonics Platform
Applications that span from sensing, to large bandwidth communication, to acoustic filtering, to high-resolution imaging and display, to quantum information processing (QIP) and to advance electronics have a growing need for new device types and materials. These advanced devices require electrical and optical properties that, in some cases, can only be provided by truly single-crystal thin-films of nonconventional materials, such as lithium niobate (LN, LiNbO3), yttrium aluminum garnet (YAG, Y3Al5O12) and diamond. In order to incorporate those crystals into existing multi-scale integrated system platforms, new technologies must be developed that can supply high-quality, single-crystal, thin-films in the desired thin-film architecture. Unfortunately, production of thin-films of single-crystals is not always possible via growth. Here, the use of Crystal Ion Slicing (CIS) technique to realize single-crystal thin-films of three of the nonconventional crystals is described. The fabrication techniques vary greatly between different crystals. Thus, new exfoliation chemistries must be developed for each material system. Detailed description of the investigation into exfoliation of LN, YAG and diamond is presented. The most mature CIS application is for LN crystals. Here, the development of several important complementary fabrication methods is presented. This includes description of polishing and bonding techniques that are necessary for successful incorporation of thin-films. Further, a lateral patterning technology of thin-films using femtosecond laser ablation is demonstrated. In addition, an ion-implantation patterning method and its application in nonlinear optics is presented. Finally, a novel polarization dependent plasmonic filter is described. In addition, a detailed description of the fabrication methods of single-crystal thin-films of YAG for acoustical and optical applications is presented. It is shown that the thermal exfoliation is the preferred method for YAG. After the thermal exfoliation, the films are subject to additional thermal cycle to anneal the films. This process high-temperature annealing is introduced to promote relaxation of film by eliminating residual strain and increasing the films' radius of curvature, both attributed to the ion-implantation process. Thus, detailed description of the post-exfoliation process is presented. The mechanical quality of the films is investigated with specific attention to the annealing behavior. Finally, the fabrication process and optical characterization of single-crystal thin-films of diamond is described. The work on diamond is focused on developing a parallel fabrication process for high-optical-quality single-crystal diamond membranes for quantum information processing (QIP) applications. The diamond membranes, with thickness as small as 200 nm and over 100 μm on their side, exhibit nitrogen-vacancy emission spectra including the zero phonon line (ZPL) peak of negatively charged centers. The films are patterned and sliced in parallel from a single-crystal diamond sample. The compatibility of the membrane with planar optical devices is demonstrated by the formation of two-dimensional photonic crystal patterns in 200 nm films. The films are produced by a combination of thermal annealing, chemical etching and oxygen plasma. Analysis of the films quality and optimization of the exfoliation process is evaluated by a verity of experimental techniques including: Atomic force microscope (AFM), optical microscopy, scanning electron microscopy (SEM), Raman and fluorescence spectroscopy, optical profilometry and nanoindentation.
Physics, Engineering, Photonics, Thin films, Photonic crystals
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