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Photonic Integrated Circuits Challenges & Solutions: Homogenization, Polarization Management and CouplingSamadian, Parya January 2015 (has links)
In recent years much effort has been carried out to make integrated photonics a widespread technology to be exploited in current optical communication industry. It is hoped
by substituting microelectronics by photonic chips and keeping the light carried by
optical fibers in light domain for further processing, the cost and speed of
communications will be vastly improved. Although this transition is challenging in
various aspects, here in this thesis some of these issues are discussed and addressed.
In this thesis firstly the limitations of current simulation tools for analysis of wide range
of photonic devices is pointed out. Structures based on photonic crystals are taken into
consideration at this point which because of finely detailed structures have shown to be
challenging to be analyzed by conventional tools. In this regard three different common
structures based on photonic crystals in both resonant and non-resonant regimes have
been considered: lamellar gratings, metamaterials for Lüneburg lens and Bragg gratings
in a LC-DFB laser. For each structure, an analytical method or homogenization approach
is proposed which is claimed to be faster for analysis of such components than numerical
methods. Comparisons of the results with conventional numerical methods prove
accuracies of each approach.
Furthermore, fiber-to-chip coupling and polarization management are discussed as other
important issues in the field of integrated photonics. Concerning polarization
management, stepped waveguide approach will be introduced as the most promising
approach for SOI and III-V substrates and designs based on this structure reported in
literature are reproduced and inaccuracies are pointed out and corrected accordingly. Also
regarding fiber-to-chip coupling, a critical appraisal of the most recent proposed
structures for edge coupling will be offered and the results will be reproduced by
simulation tools. At the end, based on detailed comparisons, the most encouraging
approach with low insertion loss and easy fabrication steps is introduced and novel
platform for easy butt coupling single mode fibers to the coupler structure is proposed.
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DEVELOPMENT AND ASSESSMENT OF POLARIZED HEAD MOUNTED PROJECTION DISPLAYSZhang, Rui January 2010 (has links)
Head mounted projection display (HMPD) technology, as an alternative to conventional head mounted displays (HMD), offers a potential of designing wide field-of-view (FOV), low distortion optical see-through HMDs (OST-HMDs). Existing HMPD designs, however, suffer from problems of low luminance and low image resolution, which limits the applications of such information displays for the scenarios which require high luminance and high image fidelity. The design of a polarized head mounted projection display (p-HMPD) was recently proposed to overcome the challenge of low luminous efficiency in existing HMPD designs. Polarization management was employed to reduce the light loss caused by beamsplitting in an HMPD.The work in this dissertation focuses on the development and evaluation of an SXGA resolution, high efficiency p-HMPD system. The main contributions are as follows. First, the key elements in the polarization management scheme of a p-HMPD were selected and their polarization performances were characterized by measuring their Mueller matrices, based on which the overall display performance of a p-HMPD was analyzed.Second, based on a pair of ferroelectric liquid-crystal-on-silicon (FLCoS) microdisplays, a compact illumination unit and a light-weight projection system were designed, from which a p-HMPD prototype was built. Following the prototype implementation, a series of calibrations were performed to obtain correct color presentation, desired focusing setting, and optical system characteristics necessary for achieving accurate registration between virtual objects and their counterparts in the real world.Third, the imaging properties of a retroreflective screen which is an essential part of a p-HMPD or HMPD were studied and its effects on the image resolution of an HMPD system were further characterized.Finally, the performance of the system was evaluated through two objective user experiments, including a visual acuity assessment and a depth perception accuracy assessment.
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