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Research And Applications Of Silicon-Based Micro/Nano Binary Nonuniform Waveguide Gratings

Posted on:2011-06-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:H M WuFull Text:PDF
GTID:1118360305492185Subject:Optical Engineering
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With the rapid development of integrated optics and silicon photonics, the grating has attracted increasing interest because some novel merits arise when the device dimension goes down to subwavelength. Combined with other optical elements, the grating related devices have made great contributions to human society and economic development. Compared with uniform gratings, the nonuniform gratings have the advantages of increasing design freedom, controlling over the Fourier series component distribution of the structures and removing the leaky modes degeneracy. They can offer the combined merits of high reflectivity over a broadband spectrum and good angular bandwidth, which makes the alignment problems encountered in implementing compact micro-optic systems quite moderate. Since silicon based micro/nano photonic devices have the advantage of a compact structure with the potential for monolithic integration with optical-to-electrical on-chip conversion and detection, all thesis work are confined in the micro/nano domain. Supported by the "National Basic Research Program of China" and "National Natural Science Foundation of China", the design and applications of the nonuniform gratings are systematically studied in this thesis, and a number of achievements are obtained as following:(1)In this thesis, a numerically stable and systematic implementation of the rigorous coupled-wave analysis (RCWA) for the general silicon-on-insulator (SOI) multilayered grating structures is presented for both transverse electric (TE) and transverse magnetic (TM) polarizations.(2)A broadband compact polarizing beam splitter (PBS) constructed by only a single layer subwavelength nonuniform profile grating is proposed and demonstrated. The properties of the grating PBS are investigated by rigorous coupled-wave analysis. It is shown that, over a broadband spectrum of 1.53~1.62μm, the grating PBS demonstrates high diffraction efficiencies with extinction ratio (ER) greater than 16dB and a comparatively wide angular bandwidth. Effects of deviation from the design parameters on the performance of the grating PBS are also presented.(3)A wideband reflector realized by only a single layer subwavelength grating is addressed. Resulting from the co-existence and interaction of TE leaky modes, over a broadband spectrum of 1.47~2.1μm, the reflector demonstrates high reflectivity and wide angular bandwidth at 1.8μm. Enhancement of light extraction in a GaN-based LED employing a nonuniform grating reflector is also proposed. The result of high angle-averaged reflectivity up to 93.5% from 300nm to 450nm predicts the potential enhancement of light-extraction efficiency of GaN LEDs with the grating reflectors.(4)A polarization insensitive reflector constructed by a multilayered grating structure with nonuniform profile is proposed. Rigorous coupled-wave analysis (RCWA) for multilayered grating structure is adopted to theoretically investigate the properties of the structure. It is shown that in both TE) and TM polarized waves, over a broadband spectrum, the reflector demonstrates very high reflectivity, low insertion loss and polarization-dependent loss and a good angular insensitivity at 1.68μm. A reasonably good tolerance of fabrication error is also presented by numerical analysis of device performance degeneration resulting from parameter deviations.
Keywords/Search Tags:Silicon photonics, Nonuniform waveguide gratings, Leaky mode resonance (LMR), Polarizing beam splitters (PBSs), Reflectors, Polarization insensitivity
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