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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Photonic Integrated Circuits Challenges & Solutions: Homogenization, Polarization Management and Coupling

Samadian, 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.
2

DEVELOPMENT AND ASSESSMENT OF POLARIZED HEAD MOUNTED PROJECTION DISPLAYS

Zhang, 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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