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This thesis encompasses a theoretical analysis, the fabrication, and optical characterization of a novel compact Bragg Slot Waveguide with a Cavity (BSWC). Strong light confinement in the low refractive index slot region formed by two silicon slabs on a silicon dioxide substrate [1] makes this structure useful for optofluidic, sensing, and optical trapping applications. The transmission spectrum of the BSWC can be engineered through the dimensional variations of the waveguide and through the refractive index change of the surrounding medium. BSWC is compact and can be integrated with various components on a chip for increased functionality. The results in this thesis show a good agreement between analytical and experimental results, while emphasizing the increasing importance of atomic-scale imperfections as a result of fabrication on the nano-scale. The impact of the slot width, slab width, and the cavity length on the waveguide transmission spectrum is investigated.

This thesis encompasses a theoretical analysis, the fabrication, and optical characterization of a novel compact Bragg Slot Waveguide with a Cavity (BSWC). Strong light confinement in the low refractive index slot region formed by two silicon slabs on a silicon dioxide substrate [1] makes this structure useful for optofluidic, sensing, and optical trapping applications. The transmission spectrum of the BSWC can be engineered through the dimensional variations of the waveguide and through the refractive index change of the surrounding medium. BSWC is compact and can be integrated with various components on a chip for increased functionality. The results in this thesis show a good agreement between analytical and experimental results, while emphasizing the increasing importance of atomic-scale imperfections as a result of fabrication on the nano-scale. The impact of the slot width, slab width, and the cavity length on the waveguide transmission spectrum is investigated.

A variable (0.2 to 5 MHz) repetition rate femtosecond laser was applied to delineate the role of thermal diffusion and heat accumulation effects in forming low-loss optical waveguides in borosilicate glass across a broad range of laser exposure conditions. For the first time, a transition from thermal diffusion-dominated transport at 200-kHz repetition rate to strong heat accumulation at 0.5 to 2 MHz was observed to drive significant variations in waveguide morphology, with rapidly increasing waveguide diameter that accurately followed a simple thermal diffusion model over all exposure variables tested. Amongst these strong thermal trends, a common exposure window of 200-mW average power and ~15-mm/s scan speed was discovered across the range of 200-kHz to 2-MHz repetition rates for minimizing insertion loss despite a 10-fold drop in laser pulse energy. Waveguide morphology and thermal modeling indicate that strong thermal diffusion effects at 200 kHz give way to a weak heat accumulation effect at ~1uJ pulse energy for generating low loss waveguides, while stronger heat accumulation effects above 1-MHz repetition rate offered overall superior guiding. The waveguides were shown to be thermally stable up to 800°C, showing promise for high temperature applications. Using a low numerical aperture (0.4) lens, the effect of spherical aberration was reduced, enabling similar low-loss waveguides over an unprecedented 520-um depth range, opening the door for multi-level, three-dimensional, optical integrated circuits. In contrast to borosilicate glass, waveguides written in pure fused silica under similar conditions showed only little evidence of heat accumulation, yielding morphology similar to waveguides fabricated with low repetition rate (1 kHz) Ti-Sapphire lasers. Despite the absence of heat accumulation in fused silica owing to its large bandgap and high melting point, optimization of the laser wavelength, power, repetition rate, polarization, pulse duration and writing speed resulted in uniform, high-index contrast waveguide structures with low insertion loss. Optimum laser exposure recipes for waveguide formation in borosilicate and fused silica glass were applied to fabricate optical devices such as wavelength-sensitive and insensitive directional couplers for passive optical networks, buried and surface microfluidic and waveguide networks for lab-on-a-chip functionality, and narrowband grating waveguides for sensing.

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We show that a 3-D microwave crossing waveguide can be solved by a 2-D scalar Helmholtz equation with combining boundary conditions for TE and TM modes. Furthermore the crossing waveguide possesses a symmetry along two diagonal axes passing through the origin. Computation of the EM wave fields is decomposed into four smaller tasks of computing reflection coefficient vector of a parallel plate waveguide terminated with a corner made of two perfectly electric or magnetic conducting walls (PECW/PMCW). In this thesis, we propose a mixed Cartesian and polar coordinate mode-matching method to solve this 2-D corner cube microwave reflection problem. The solution is obtained by applying the continuity condition of both the tangential field and its normal derivative along a given curve inside the overlapped region of the two coordinate systems. We are able to compute up to the third decimal place of the reflection, through and cross transmission coefficients. All results pass the energy conservation test and are verified and compared with those computed by Integral equation method simulation.

1x8 optical power splitters on silicon substrate were successfully fabricated based on polyimide channel waveguides structure. The 1x8 power splitter was first designed by bean propagation method. The device was fabricated using polyimide provided by Eternal chemistry. The TE propagation loss of the waveguide is 1.4dB with a index contrast of 0.73%. However, the waveguide is not able to support low-loss propagation of TM polarized light. The chip size of the 1x8 power splitter is 17mm x 3mm. After fabrication, the optical characteristics of the splitter were measured.

In this study, we research the characteristic of light in the waveguide with etched ITO channels. The anisotropic of liquid crystal induces the index of reflection changed while applying alternative voltage. The etched ITO electrode will become waveguide in cell by applying alternative voltage. We observe the characteristic of light with different number of channels. Single ITO channel results graded type reflection index distribution, and it is similar to graded type optical fiber. We find that the laser beams will induce coupling in channels with many etched ITO channels.