Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains x, 114 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 112-114).

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [180]-182).

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2004. / Dr. William P. King, Committee Member ; Dr. F. Levent Degertekin, Committee Member ; Dr. Thomas R. Kurfess, Committee Chair.

Thesis (Ph. D.)--Drexel University, 2005. / Includes abstract and vita. Includes bibliographical references (leaves 127-132).

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 50-54). Also available on the World Wide Web.

Thesis (Ph.D.)--Victoria University (Melbourne, Vic.), 2009.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 182-184).

The aim of this project is to fabricate highly efficient grating couplers in thin-film silicon-on-insulator (SOI) wafers, which have a silicon (Si) thickness of the order of 1 mum. These thin-film waveguides allow the development of higher speed Si optical modulators, sensors and vertical surface coupling for Si light emitting diodes (LEDs), Hence, SOI rectangular and blazed grating couplers were fabricated where the buried oxide layer in SOI was designed as a reflective layer. The former gratings were fabricated by electron beam lithography followed by reactive ion etching, while the latter gratings were fabricated by angled argon ion beam etching. Both types of grating were designed at the diffraction order of -1, for a wavelength of 1.3 mum. The fabricated rectangular gratings have grating heights of 0.14, 0.23, 0.30 and 0.44 mum and a pitch of 0.40 mum whereas the sawtooth blazed gratings have a grating depth of 0.08 mum and a period of 0.38 mum To our knowledge, no Si blazed gratings with a pitch of less than 500 nm have been fabricated before. The SOI rectangular grating couplers yield a maximum output efficiency of 71 +/- 5 % towards the superstrate, while the blazed grating couplers produce an output efficiency of 84 +/- 5 % towards the substrate. These experimental output efficiencies are the highest yet reported in SOI for each grating profile, respectively. In addition, an optical loss of 0.15 +/- 0.05 dB/cm of Unibond SOI was measured for the first time. Furthermore, the experimental output efficiencies of the grating couplers with various grating heights were found to be consistent with perturbation theory. Thus, our aim of designing and fabricating an highly efficient thin film SOI waveguide grating coupler has been achieved. These grating couplers may enhance the applications of integrated optics in Si, and may allow the development of devices such as those mentioned above.

M.Ing. / Bragg gratings are important components for sensing and for wavelength-division multiplexed optical communication systems. These gratings are manufactured by either side-writing of the fiber with a high intensity UV light through a phase mask, or by exposing the fiber to interference fringes through an interferometer arrangement. With one phase mask, only a small range of grating wavelengths is possible. This is achieved by pre-straining the fiber during the writing process. The limitation arises from the break strength of the fi ber, allowing a maximum range of Bragg wavelengths of only approximately 10 nm. The interferometric technique uses a beam splitter to divide a single input UV beam into two and intersecting them at the fiber. The angle at which the beams intersect will determine the period of the interference fringes and thus the Bragg grating written in the optical fiber. The Argon-ion laser is used with a 1060 nm phase mask (used to split beam) to write Bragg gratings with reflections from 1012 to 1600 nm. Three accurate- translation and rotation stages are used to keep the fiber at the beam intersection. Alignment, mechanical stability and coherence of laser are critical.

M.Phil. / Linearly chirped fibre Bragg gratings can be used to compensate dispersions in a fibre transmission system. Various methods have been developed to chirp fibre gratings. It is proposed that a uniform period grating can be chirped by applying an axially linear strain gradient. In this project, we shall demonstate a novel method for making chirped fibre Bragg gratings, which involves bonding an unchirped fibre Bragg grating of 5cm length to the surface of a tapered stainless steel plate which is strained by bending or dilating. This allows a strain gradient to be formed along the grating length through the transferring of strains from the plate to the fibre. The profiles of tapered stainless steel plates have been determined by means of the finite element method and computer simulations to establish the strain gradient during loading. Ten conventional resistive strain gauges are also bonded on the other surface for strain measurements. Because of the strain gradient, the local Bragg wavelength is a function of the position along the length of the fibre grating so that the grating chirp is an automatic consequence of the strain gradient. This method provides the dynamic control of Bragg wavelength shift, peak reflectivity and spectral bandwidth, and its tunability is also suitable for optimising pulse compression and optical fibre dispersion compensation. Using couple-mode equations, we have also calculated the reflection response of a chirped fibre grating. It is shown that the close agreement between the theoretical and the experimental results suggests that the strain gradient technique provides good control of the Bragg grating chirp and the center wavelength of a chirped fibre Bragg grating.