Dissertations / Theses on the topic 'Waveguide'
To see the other types of publications on this topic, follow the link: Waveguide.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Waveguide.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Fuhse, Christian. "X-ray waveguides and waveguide-based lensless imaging." Doctoral thesis, [S.l.] : [s.n.], 2006. http://webdoc.sub.gwdg.de/diss/2006/fuhse.
Full text
2
Lu, Junjie. "Modelling optical waveguide bends and applications to plasmon-polariton waveguides." Thesis, University of Ottawa (Canada), 2003. http://hdl.handle.net/10393/26516.
Full textAbstract:
Optical waveguide bends are key building blocks in many integrated optical components. Accurate numerical modelling of these bends is of great practical value to the design of the integrated optical technology. Analyzed in this thesis are the propagation characteristics of optical waveguide bends based on the method of lines (MoL), not only for its good numerical performances (accuracy, speed of computation and minimal memory requirements), but also for its high suitability for the analysis of waveguide structures.
This thesis gives the detailed formulation for the calculation of the waveguide-bending radiation loss and the transition loss due to modal mismatch at the junctions. Besides, the 1D and 2D spatial field distribution algorithms are also covered in the formulation.
The code based on the formulation has been implemented successfully. To validate the code, we applied it to three typical waveguide structures appearing in other literatures and compared the results. The comparison shows that our code works very well, and can be used not only for the lossless dielectric media, but also for the lossy media at the optical frequency.
This thesis also explores the application of the developed code to metal waveguide bends. The numerical results of the propagation characteristics of the metal waveguide bends at the optical frequencies are presented for what is believed to be the first time.
3
Huang, Xuefeng. "Ion implanted optical waveguides and laser ablated Bragg waveguide gratings." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364140.
Full text
4
Kim, Jinkee. "Analysis of optical waveguide discontinuities and design of planar prisms in waveguides." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13878.
Full text
5
Cockrell, Kevin L. "Understanding and utilizing waveguide invariant range-frequency striations in ocean acoustic waveguides." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/65275.
Full textAbstract:
Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and the Woods Hole Oceanographic Institution), February 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 163-170).
Much of the recent research in ocean acoustics has focused on developing methods to exploit the effects that the sea surface and seafloor have on acoustic propagation. Many of those methods require detailed knowledge of the acoustic properties of the seafloor and the sound speed profile (SSP), which limits their applicability. The range-frequency waveguide invariant describes striations that often appear in plots of acoustic intensity versus range and frequency. These range-frequency striations have properties that depend strongly on the frequency of the acoustic source and on distance between the acoustic source and receiver, but that depend mildly on the SSP and seafloor properties. Because of this dependence, the waveguide invariant can be utilized for applications such as passive and active sonar, time-reversal mirrors, and array processing, even when the SSP or the seafloor properties are not well known. This thesis develops a framework for understanding and calculating the waveguide invariant, and uses that framework to develop signal processing techniques for the waveguide invariant. A method for passively estimating the range from an acoustic source to a receiver is developed, and tested on experimental data. Heuristics are developed to estimate the minimum source bandwidth and minimum horizontal aperture required for range estimation. A semi-analytic formula for the waveguide invariant is derived using WKB approximation along with a normal mode description of the acoustic field in a rangeindependent waveguide. This formula is applicable to waveguides with arbitrary SSPs, and reveals precisely how the SSP and the seafloor reflection coefficient affect the value of the waveguide invariant. Previous research has shown that the waveguide invariant range-frequency striations can be observed using a single hydrophone or a horizontal line array (HLA) of hydrophones. This thesis shows that traditional array processing techniques are sometimes inadequate for the purpose of observing range-frequency striations using a HLA. Array processing techniques designed specifically for observing range-frequency striations are developed and demonstrated. Finally, a relationship between the waveguide invariant and wavenumber integrations is derived, which may be useful for studying range-frequency striations in elastic environments such as ice-covered waveguides.
by Kevin L. Cockrell.
Ph.D.
6
Midgley, Stuart. "Quantum waveguide theory." University of Western Australia. School of Physics, 2003. http://theses.library.uwa.edu.au/adt-WU2004.0036.
Full textAbstract:
The study of nano-electronic devices is fundamental to the advancement of the semiconductor industry. As electronic devices become increasingly smaller, they will eventually move into a regime where the classical nature of the electrons no longer applies. As the quantum nature of the electrons becomes increasingly important, classical or semiclassical theories and methods will no longer serve their purpose. For example, the simplest non-classical effect that will occur is the tunnelling of electrons through the potential barriers that form wires and transistors. This results in an increase in noise and a reduction in the device?s ability to function correctly. Other quantum effects include coulomb blockade, resonant tunnelling, interference and diffraction, coulomb drag, resonant blockade and the list goes on. This thesis develops both a theoretical model and computational method to allow nanoelectronic devices to be studied in detail. Through the use of computer code and an appropriate model description, potential problems and new novel devices may be identified and studied. The model is as accurate to the physical realisation of the devices as possible to allow direct comparison with experimental outcomes. Using simple geometric shapes of varying potential heights, simple devices are readily accessible: quantum wires; quantum transistors; resonant cavities; and coupled quantum wires. Such devices will form the building blocks of future complex devices and thus need to be fully understood. Results obtained studying the connection of a quantum wire with its surroundings demonstrate non-intuitive behaviour and the importance of device geometry to electrical characteristics. The application of magnetic fields to various nano-devices produced a range of interesting phenomenon with promising novel applications. The magnetic field can be used to alter the phase of the electron, modifying the interaction between the electronic potential and the transport electrons. This thesis studies in detail the Aharonov-Bohm oscillation and impurity characterisation in quantum wires. By studying various devices considerable information can be added to the knowledge base of nano-electronic devices and provide a basis to further research. The computational algorithms developed in this thesis are highly accurate, numerically efficient and unconditionally stable, which can also be used to study many other physical phenomena in the quantum world. As an example, the computational algorithms were applied to positron-hydrogen scattering with the results indicating positronium formation.
7
Bain, Fiona Mair. "Yb:tungstate waveguide lasers." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1698.
Full textAbstract:
Lasers find a wide range of applications in many areas including photo-biology, photo-chemistry, materials processing, imaging and telecommunications. However, the practical use of such sources is often limited by the bulky nature of existing systems. By fabricating channel waveguides in solid-state laser-gain materials more compact laser systems can be designed and fabricated, providing user-friendly sources. Other advantages inherent in the use of waveguide gain media include the maintenance of high intensities over extended interaction lengths, reducing laser thresholds. This thesis presents the development of Yb:tungstate lasers operating around 1μm in waveguide geometries. An Yb:KY(WO₄)₂ planar waveguide laser grown by liquid phase epitaxy is demonstrated with output powers up to 190 mW and 76 % slope efficiency. This is similar to the performance from bulk lasers but in a very compact design. Excellent thresholds of only 40 mW absorbed pump power are realised. The propagation loss is found to be less than 0.1 dBcm⁻¹ and Q-switched operation is also demonstrated. Channel waveguides are fabricated in Yb:KGd(WO₄)₂ and Yb:KY(WO₄)₂ using ultrafast laser inscription. Several of these waveguides lase in compact monolithic cavities. A maximum output power of 18.6 mW is observed, with a propagation loss of ~2 dBcm⁻¹. By using a variety of writing conditions the optimum writing pulse energy is identified. Micro-spectroscopy experiments are performed to enable a fuller understanding of the induced crystal modification. Observations include frequency shifts of Raman lines which are attributed to densification of WO₂W bonds in the crystal. Yb:tungstate lasers can generate ultrashort pulses and some preliminary work is done to investigate the use of quantum dot devices as saturable absorbers. These are shown to have reduced saturation fluence compared to quantum well devices, making them particularly suitable for future integration with Yb:tungstate waveguides for the creation of ultrafast, compact and high repetition rate lasers.
8
Tan, Shunyi. "Holographic waveguide display." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610434.
Full text
9
Choudhary, Amol. "Ultrafast waveguide lasers." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/362084/.
Full textAbstract:
Mode-locked lasers with repetition-rates in excess of 1 GHz have many applications in areas such as optical sampling, non-linear microscopy, and optical frequency metrology. To date there have been very few demonstrations of such high repetition-rate lasers with sub-picosecond operation and high average power. This thesis deals with the realisation of such compact sources using an integrated-optics platform. Waveguides offer certain key advantages, including a low threshold power, high slope efficiency, compatibility with monolithic devices, and a low mode-locking threshold, making them very promising candidates for such devices. Ultrafast multi-GHz waveguide lasers are described in this thesis, which are compact, mass-producible and low-cost making them very exciting candidates for industrial applications. Mode-locking was demonstrated in an ion-exchanged Yb:phosphate glass waveguide laser with integrated saturable absorber elements. An average output power as high as 80 mW was achieved at a pulse repetition frequency (PRF) of 4.9 GHz, at a wavelength around 1 m and with pulse durations as short as 740 fs. Using shorter cavity lengths, waveguide lasers with PRFs of 10.4 GHz, 12 GHz and 15.2 GHz were achieved with pulse durations between 757 fs and 824 fs. A Gires Tournois Interferometer (GTI) effect was used to facilitate soliton mode-locking in the waveguides via accurate control of the gap between the waveguide and the output coupling mirror. This is a convenient technique to control the dispersion without introducing any extra elements in the laser cavity. Two further Yb-doped ultrafast laser hosts, RbTiOPO4 and KY(WO4)2, were investigated for their potential as ultrafast waveguide laser sources, having both been previously demonstrated as good bulk ultrafast systems. Laser action was demonstrated for the first time in an (Yb,Nb):RbTiOPO4 planar waveguide laser, fabricated by liquid-phase epitaxy. Ion-beam milling was then used to fabricate the first ever single-mode rib waveguides in (Yb,Nb):RbTiOPO4 fabricated by dry etching techniques but laser action was not possible due to propagation losses of ~3dB/cm. A systematic study of the reactive ion etching of RbTiOPO4 was then carried out to minimise the surface roughness, in an attempt to reduce the propagation losses. The first ever demonstration of single-mode waveguiding in (Yb,Nb):RbTiOPO4 fabricated by reactive ion etching was demonstrated but the propagation losses remained high. Using (Yb,Gd,Lu):KY(WO4)2 as a gain media, efficient laser action was demonstrated in an “inverted-rib” waveguide laser structure fabricated by ion-beam milling. This laser was found to have a threshold power as low as 13 mW and a maximum slope efficiency of 58% and showed characteristics of a pure 3-levellaser by lasing at 981 nm. However, further loss reduction is again required in order for efficient ultrafast operation to be obtained in the future. Mode-locked waveguide laser operation was extended to the 1.5μm spectral region based on an ionexchanged Er,Yb:phosphate glass waveguide laser using a novel SESAM based on a quantum dot in well (DWELL) structure. 2.5 ps pulses at a PRF of 4.8 GHz and an average output power of 9 mW were achieved. With a shorter waveguide sample, a PRF of 6.8 GHz with an average output power of 30 mW and pulse duration of 5.4 ps was achieved. The repetition-rate of the laser was finely tuned by controlling the pump power offering an attractive technique for enabling future frequency-comb stabilisation. This is the highest reported repetition-rate from a mode-locked waveguide laser at 1.5 m and is also the first ever waveguide laser mode-locked by a quantum dot SESAM. Finally, as an intitial step towards further extension to the 2μm spectral region, laser action was demonstrated, for the first time, in an ion-exchanged Tm:glass waveguide laser with a threshold power as low as 44 mW and a maximum slope efficiency of 6.8% around 1.9 m. Designs for power-scaling of such sources have also been discussed in this thesis.
10
Hettrick, Simon James. "Tapered waveguide lasers." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/15471/.
Full textAbstract:
The work reported in this thesis concerns the design and fabrication of tapered waveguide lasers to allow efficient, high-power diode-pumping and produce diffraction-limited, near-symmetrical output, whilst maintaining a monolithic design compatible with integrated optical circuits. The design rules required for efficient operation of a tapered waveguide are derived, and applied to the fabrication of tapered waveguides by thermal ion exchange (TIE) in Nd-doped borosilicate glass. Ti:sapphire pumped laser operation of these waveguides indicates efficient (40%) and low-loss (0:2dBcm-1) operation, comparable to that of a channel waveguide fabricated within the same substrate. Parabolic and linear taper shapes are compared, and the linear shape is found to provide superior operation at wide taper expansions (up to 250μm, over a length of ~ 22mm), and hence is more suited to end-pumping with multi-watt broad-stripe-diodes. Broad-stripe-diode end-pumping is also investigated, and the laser performance is characterised, indicating a need to control the refractive index profile to maximise the overlap of the multimode-pump and single-mode laser. Field-assisted ion exchange is therefore investigated to improve the overlap of the diode-pump and laser modes in a tapered waveguide. Waveguides produced by this technique are shown to exhibit the desired step-like index profile, but require further optimisation to improve the laser performance. Low-loss (0:1dBcm-11) operation of a tapered waveguide laser is reported in a hybrid Nd-doped/undoped borosilicate glass. The hybrid glass is proposed as a useful substrate for reducing the quasi-3-level reabsorption loss of Yb3+-doped lasers. As an initial step towards this goal, channel waveguides are fabricated in standard Yb3+-doped phosphate glass, which exhibit efficient (50-75%) and moderate-loss (0:6dBcm-1) laser operation. The design requirements for a power scalable diode-side-pumped tapered waveguide laser are also investigated, and YVO4 is proposed as a suitable substrate material due to its high absorption coefficient. The indiffusion of Nd, Gd and Ti is characterised for the first time, and the fabrication of the first Nd-indiffused waveguide in YVO4 is reported.
11
Kinsey, Geoffrey Sherwood. "Waveguide avalanche photodetectors /." Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3008370.
Full text
12
Barkley, Edward R. (Edward Robert). "The integration of InP /InGaAsP ridge waveguide structures with dielectric waveguides on silicon." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38682.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2007.Includes bibliographical references (p. 261-271).
Chip-to-chip optical interconnect technology, which is being explored as a potential replacement for copper chip-to-chip interconnects at data transmission rates exceeding 10 Gb/s, is one of several technologies that could be enabled by the monolithic integration of III-V optoelectronic devices on a silicon integrated circuit. Two significant capabilities required to achieve this monolithic integration were addressed: the assembly of III-V device structures on silicon and the fabrication of the waveguides that perform the intra-chip routing of the optical signal to and from these integrated device structures. These waveguides, consisting of a silicon oxynitride core (n = 1.6) and a silicon dioxide cladding (n = 1.45) were deposited via plasma-enhanced chemical vapor deposition (PECVD). The integrated InP/InGaAsP structures were fabricated using an existing novel technique for preparing very thin (on the order of 5 pm thick) substrate free rectangular structures (approximately 145 pm wide by 300 pm long) with cleaved facets. Using a pick-and-place method, the InP/InGaAsP structures were assembled in 6 pm deep rectangular wells formed by etching through the waveguide stack. The resulting configuration of the integrated devices in the wells facilitated end-fire coupling with the silicon oxynitride waveguides.
(cont.) Transmission spectrum measurements for this configuration verified the desired end-fire optical coupling through the integrated InP/InGaAsP device structures with a total coupling loss of 17.75 dB. This loss was shown through measurements and finite difference time domain (FDTD) simulations to be a function of integrated device misalignment, silicon oxynitride waveguide design, length of the gaps between the etched well edges and the device facets, and the well etch properties. Based on FDTD simulations and device misalignment statistics, it was shown that realistic, feasible improvements in the device alignment coupled with the use of higher index contrast waveguides could lower the coupling loss to 3.25 dB.
by Edward R. Barkley.
Ph.D.
13
Juvalta, Flurin. "Light-induced waveguides, waveguide arrays and switches in photorefractive LiTaO₃ and Sn₂P₂S₆ /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18105.
Full text
14
Høvik, Jens. "Photonic Crystal Waveguide Fabrication." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19277.
Full textAbstract:
This research is entirely devoted to the study and fabrication of structures with periodic dielectric constants, also known as photonic crystals (PhCs). These structures show interesting dispersion characteristics which give them a range of prohibited frequencies that are not allowed to propagate within the crystal. This property makes them suited for a wide array of photonic-based components. One-dimensional photonic crystals are already commercialized and are of widespread use in for example thin-film optics, and two-dimensional PhCs are available in the form of photonic crystal fibers.Much work is being done on the analysis of photonic crystals and their application in various photonic components. In designing any photonic crystal component the properties of the crystal must first be understood and analyzed. By using frequency-domain simulation software we have studied the properties of bulk photonic crystals and designed the ideal structure for confining light of any design wavelength within a three-dimensional photonic crystal slab.Through simulations, the ideal periodicity of the PhC has been found along with its optimal geometry for waveguiding purposes. The study was then extended to three dimensions and the optimal thickness of the PhC slab was found. By using these determined values we were able to properly confine light inside a defect in a photonic crystal structure. This phenomenon allowed us to briefly examine the use of a photonic crystal as a waveguide. This research was then continued by attempting to fabricate such a device. Methods entailing how to create a silicon-on-insulator wafer through plasma enhanced chemical vapor deposition were developed. Profilometry, refractometry and ellipsometry were used to characterize the quality of the SOI wafer. A surface roughness between 1.5-3.5 nm was found. The losses of the amorphous silicon was attempted to be measured through ellipsometry, but the ellipsometer was found incapable for loss meassurements. Better testing methods must therefore be developed.The PhC waveguiding structure is formed thorugh electron-beam lithography, and various thicknesses of photoresist are tested and characterized. Furthermore, various materials were attempted as an etch mask. Polymethyl methacrylate, $SiO_2$, and chromium were all utilized, where only the latter showed good enough selectivity for silicon etching. This lead to using both chromium and $SiO_2$ as the mask of choice. Several etching methods were tested. Both standard wet etching, room-temperature reactive ion etching recipes as well as cryogenic inductively coupled plasma reactive ion etching recipes were employed. Dry etching was found to be of insufficient quality, while the complete isotropy of wet etching rendered it impractical for fine structures needed for a PhC waveguide.The final solution which allowed the formation of the photonic crystal was a stacked structure, using both chromium, oxide, and PMMA throughout the etching process in order to achieve the wanted results. The PMMA was used as an etch mask to imprint the pattern in the oxide layer. The oxide layer was in turn used as an etch mask to imprint the pattern into the chromium, and the chromium served as the final mask to be used during cryogenic silicon etching. The cryogenic silicon etching recipe was characterized and shown to be sufficiently anisotropic as well as having a rather high maximum etch depth. The recipe show an unwanted formation of so-called silicon grass, and a high sidewall roughness is observed. Finally, a complete PhC waveguiding structure with both a grating, a taper, and a silicon waveguide is fabricated. Although they require more work to be optimized, the methods presented in this thesis provide the basis for fabricating a multitude of optical components, not only PhC's.
15
Sibbald, Christopher L. "Open-ended waveguide structures." Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5576.
Full text
16
Zhong, Jiang-Jian. "Tapered waveguide display panel." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620034.
Full text
17
Lau, Fat Kit. "Tapered waveguide laser diodes." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611648.
Full text
18
Zhang, Cui. "Integrated waveguide optical isolator." Thesis, University of Glasgow, 2017. http://theses.gla.ac.uk/7994/.
Full textAbstract:
This project is aimed at the integration of a polarisation-insensitive optical waveguide isolator on a Silicon-on-Insulator platform. The final device must provide comparable performance for both Transverse Electric and Transverse Magnetic modes at a wavelength of 1550 nm. This is achieved through two core components, a 45° Nonreciprocal Polarisation Mode Converter, and a 45° Reciprocal Polarisation Mode Converter. In order to realise the Nonreciprocal Polarisation Mode Converter, several materials were investigated, all consisting of Silicon-on-insulator substrates with various thicknesses of the core layer that were coated with films of Magneto-Optic garnet materials. A wide number of Magneto-Optic garnet materials were tested. Among them, the Cerium-Terbium Iron Garnet proved the most promising for two reasons: first, it has a considerable Faraday rotation coefficient; secondly, it can be grown in crystalline form without the need for a buffer/seed layer, necessary for growing most other garnets. Simulations were carried out for all grown materials in order to identify the most promising design. The simulated designs, however, could not always be translated into fabricated devices, as sometimes growth challenges would hinder the quality of the material. Since the growths on the 340 nm and 500 nm Silicon-on-Insulator platforms provided the best material quality, devices on these material systems were fabricated and optically characterised. Nonreciprocal isolation performance was observed in all fabricated devices, independently of the Magneto-Optic garnet used. On the 340 nm Silicon-on-Insulator platform, the best performance was obtained when Bismuth-Terbium Iron Garnet, either on its own or in combination with Terbium Iron Garnet, was used as Magneto-Optic periodic cladding, leading to more than 3/4π Stokes vector angle. On the 500 nm Silicon-on-Insulator platform instead, Cerium-Yttrium Iron Garnet, either by Magnesium Oxide or on Yttrium Iron Garnet, provided a calculated isolation ratio of 11.6 dB. The length of the fabricated devices ranged between 3 mm and 6 mm. A reproducible device fabrication process, optical characterisation method and dedicated data analysis process had to be developed for this project. Nonreciprocal Polarisation Mode Conversion was demonstrated for devices on both the 500 nm and 340 nm Silicon-on-Insulator platforms. Moreover, in order to achieve integration of Magneto-Optic garnet materials on Silicon-on-Insulator substrates, Radio-Frequency sputtering was preferred to wafer bonding as it improves the controllability and lends itself better to scaling up production. With regard to the Reciprocal Polarisation Mode Converter, an asymmetric structure consisting of an L-shaped waveguide was chosen. In such a structure, the rotation of the optical axis enables an injected linear polarisation mode to excite hybrid modes and reciprocal mode conversion. The research carried out in this project for the reciprocal polarisation mode converter helped identify major issues with fabrication and characterisation, and lead to the proposal of a new design for further research. This work successfully realised the first integrated polarisation-independent Faraday rotator showing comparable performance for both Transverse Electric and Transverse Magnetic modes. Device operation was based on nonreciprocal polarisation mode conversion, and it was demonstrated on both 500 nm and 340 nm Silicon-on-Insulator platforms. The results shown in this work in terms of performance and footprint prove the technology is suitable for optical integration.
19
MORIWAKI, Osamu, Ken-ichi SATO, Hiroshi HASEGAWA, and Shoji KAKEHASHI. "Formulation of Waveguide Connection for Waveband MUX/DEMUX Using Concatenated Arrayed-Waveguide Gratings." Institute of Electronics, Information and Communication Engineers, 2007. http://hdl.handle.net/2237/14992.
Full text
20
Field, Paul A. "Wavelength stabilisation for high power CO2 slab waveguide lasers using waveguide surface patterning." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/472.
Full text
21
Klaren, Jonathan J. (Jonathan James). "Mode-matching analysis for discontinuities in waveguide and application to a waveguide circular polarizer." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36466.
Full textAbstract:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 70-71).
by Jonathan J. Klaren.
M.S.
22
Trantanella, Charles Joseph 1967. "A waveguide power balance theorem applied to a parallel plate waveguide with an iris." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/278047.
Full textAbstract:
We study the problem of wave propagation in a parallel plate waveguide with an iris. We use Green's function techniques to model the field behavior inside the waveguide. We formulate an integral equation whose solution will allow us to solve for the fields everywhere within the guide. We solve the integral equation by employing both the method of moments and a low-frequency approximation. We next develop a power balance theorem which relates the modal coefficients of the propagating modes in an exact relation. From the numerical solution, we can generate numerical approximations to the modal coefficients. We investigate if and when our numerical approximations to the modal coefficients satisfy the power balance theorem. Finally, we derive a generalized power balance theorem for scattering by obstacles and junctions inside a waveguide of arbitrary, uniform cross-sectional area.
23
Johansson, Christer. "Numerical methods for waveguide modeling /." Stockholm : Numerical Analysis and Computing Science (NADA), Stockholm university, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-992.
Full text
24
Walker, David B. "Ferroelectric liquid crystal waveguide modulators." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13277.
Full text
25
Shackleton, Christian John. "Resonators for slab-waveguide lasers." Thesis, Heriot-Watt University, 1993. http://hdl.handle.net/10399/1387.
Full text
26
Wang, Xu. "Silicon photonic waveguide Bragg gratings." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45687.
Full textAbstract:
Silicon is the most ubiquitous material in the electronics industry, and is now expected to revolutionize photonics. In just over ten years, silicon photonics has become a key technology for photonic integrated circuits. By taking advantage of silicon-on-insulator (SOI) wafers and the existing complementary metal-oxide semiconductor (CMOS) fabrication infrastructure, silicon photonic chips are now being delivered with low cost and rapidly increasing functionality.
This thesis presents the integration of a fundamental optical device - Bragg grating - into SOI waveguides. Various types of waveguides and grating structures have been investigated. All designs are fabricated using CMOS foundry services. We have also explored various applications using the fabricated devices.
From the beginning, we focused on strip waveguide uniform gratings, as these are the most simple to design and fabricate. We have studied many design variations, supported by experimental results. In parallel, we have provided insight into practical issues and challenges involved with the design, fabrication, and measurement, such as the lithography effects, thermal sensitivity, and wafer-scale nonuniformity. We then introduce phase-shifted gratings that can achieve very high quality factors and be employed in various applications. We have also demonstrated sampled gratings and the Vernier effect in strip waveguides.
To obtain narrow-band gratings, we propose the use of a rib waveguide. We also propose a multi-period grating concept by taking advantage of the multiple sidewalls of the rib waveguide, to increases the design flexibility for custom optical filters. The wafer-scale data shows that rib waveguide gratings have better performance uniformity than strip waveguide gratings, and that the wafer thick- ness variation is critical. Additionally, we have demonstrated very compact Bragg gratings using a spiral rib waveguide.
Finally, we demonstrate slot waveguide Bragg gratings and resonators, which has great potential for sensing, modulation, and nonlinear optics. We have also developed a novel biosensor using a slot waveguide phase-shifted grating that has a high sensitivity, a high quality factor, a low limit of detection, and can interrogate specific biomolecular interactions.
27
Abram, Richard Henry. "High power waveguide array lasers." Thesis, Heriot-Watt University, 1998. http://hdl.handle.net/10399/622.
Full text
28
Reilly, Mark Alexander. "Integrated polymer waveguide optical amplifiers." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614010.
Full text
29
Cao, Qiusheng. "Planar waveguide CO2 laser amplifiers." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/1224.
Full text
30
Zourob, Mohammed M. "Development of optical waveguide biosensors." Thesis, University of Manchester, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.743091.
Full text
31
Field, Simon John. "Ion implanted crystal waveguide lasers." Thesis, University of Southampton, 1992. https://eprints.soton.ac.uk/399433/.
Full textAbstract:
This thesis reports the first use of He+ implantation to create integrated optic waveguide lasers, by modifying the refractive index of bulk laser host crystals. He+ ion implantation produces a variety of refractive index changes within different target (implanted) crystals which can be used to create planar and channel optical waveguides with propagation losses of the order of 1dB/cm. The spectroscopic properties of the laser impurity dopant in the target crystal are generally not altered drastically by the implantation. The fluorescence lifetime is typically unchanged in the waveguide compared to the bulk crystal, but the fluorescent emission lines are broadened to an extent dependent on the implanted ion dose used to fabricate the waveguide. The wide ranging applicability of the fabrication technique has been demonstrated, with planar waveguide laser action reported in 5 neodymium doped materials, Nd:YAG, Nd:YAP, Nd:MgO:LiNbO3, Nd:Bi4Ge3O12 and Nd:GGG. Diode-pumped laser operation has been demonstrated. with absorbed power thresholds of around 10mW, slope efficiencies up to 30% and output powers up to 40mW. The fabrication of gold ion-stopping masks several microns thick using photolithographic patterning has allowed the creation of the first index enhancement ion implanted channel waveguides, with channel waveguide laser action demonstrated in Nd:YAG and Nd:GGG. Very low laser thresholds of around 500µW absorbed power have been obtained with diode-pumping of Nd:YAG, comparable with the best results achieved with single-crystal fibre growth. Slope efficiencies of 30% have been achieved in both Nd:YAG and Nd:GGG. This thesis also reports the first use of ion implantation to create waveguides in tunable laser crystal hosts, Alexandrite and Cr:YSAG. The spectroscopic properties of the chromium laser impurity are found to be little changed by the waveguide fabrication process, offering hope for the future creation of a tunable channel waveguide laser. In addition, the phenomenon of optically written channel waveguides within ion implanted planar waveguides in Bi4Ge3O12 is reported here. Launching a moderate power (~50mW) laser beam into a He+ implanted planar BGO waveguide creates a permanent channel waveguide structure. Extension of this writing technique to a beam incident on the planar waveguide top surface could allow the production of complex integrated optic circuits, and results of initial experiments of this type are presented.
32
Harris, Richard David. "Waveguide surface plasmon resonance biosensor." Thesis, University of Southampton, 1996. https://eprints.soton.ac.uk/398739/.
Full textAbstract:
This thesis reports the design and development of the first waveguide surface plasmon resonance (SPR) biosensor for pesticide analysis. The integrated optical format allows the fabrication of a compact sensor that may be connected to optical fibre; necessary steps towards a portable optical biosensor. A major advantage of the integrated optical approach is the possibility of fabricating multiple sensors on one substrate, and hence testing for multiple analytes in one basic assay. The SPR structure incorporates a metal film that may be employed as an electrode to study the electrochemical control of sensing reactions. The performance of such devices requires analysis of the waveguide modes supported by the metal-clad waveguide, of their excitation by an input waveguide and of the resultant power coupled into an output waveguide. For the first time a rigorous numerical waveguide model to study the power transmission of such general multilayer absorbing structures has been developed. The model allows the determination of the modulation in output power of the sensor due to the adsorption of a thin organic layer to the sensor surface, which in turn leads to a measure of sensitivity. Designs for practical, sensitive, waveguide SPR sensors for an aqueous environment, optimised for specific sensing films are reported. The fabrication of gold-coated, potassium ion-exchanged, waveguide SPR sensors in soda-lime and Pyrex glass is reported. Three types of experiment were performed to validate the waveguide model using these devices. The first involved measuring changes in the output power of the sensor as a function of gold film length. The second measured the SPR response of sensors as a function of gold film parameters. Third, the effect on the SPR response of binding a dual layer of biotin-avidin to the sensor surface was observed as a function of gold film thickness. Predictions of the waveguide model were compared to the experimental data. Optimisation of the sensor design through these experimental procedures is also described. The transformation of the basic waveguide SPR sensor into a specific biosensor for the triazine herbicides simazine and atrazine is reported. The assay procedure was based on anti-simazine and anti-atrazine IgG antibodies and their Fab fragments developed by co-workers at GEC Marconi Materials Technology Ltd., UK Chemical modification of the sensor surface was developed by co-workers at the University of Tubingen, Germany, to bind the antibodies to the sensor surface. Laboratory characterisation of the sensor as a simazine sensor was performed and is reported in this thesis. Extended validation identified a detection limit of 0.22µg/l for the herbicide simazine in the aqueous environment. The biosensor gave a significant correlation with HPLC measurements on natural water samples when the cross-reactivity of the sensor with other triazine herbicides was taken into account.
33
Adikan, Faisal Rafiq Mahamd. "Direct UV-written waveguide devices." Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/65507/.
Full textAbstract:
This thesis describes a series of experimental studies concerning waveguide structures based on the direct UV and direct grating writing fabrication techniques. The latter approach allows simultaneous definition of waveguide structures and Bragg gratings. The first result of this work describes the fabrication and characterisation of small angle X-couplers that exhibit low polarisation and wavelength dependence. Maximum and minimum coupling ratios of 95% (±0.8%) and 1.9% (±1%) respectively with typical excess loss of 1.0dB (±0.5dB) were recorded. Device modelling using Beam Propagation Method (BPM) and an analytical model showed good agreement with experimental results over a broad crossing angle and wavelength range. By introducing refractive index asymmetry in 2° X-couplers, it was possible to tune the response to give a 50:50 coupling ratio. Multiple UV exposure experiments investigated the 'proximity effect' and provided further proof of the ability of UV writing to produce raised waist index X-couplers. A first order Bragg grating electrically tunable via liquid crystal index modification with a maximum tunability of 141 GHz at 1562nm (TM polarised) and 114 GHZ at 1561.8nm (TE polarised) using electro-patterned ITO-coated glass electrodes is also presented. The 141GHz tuning range effectively covers up to five 25 GHz WDM channel spacing and was achieved with 170Vpp sinusoidal 1 kHz supply voltage. Hysteretic behaviour of the tuning curves was observed and is believed to be related to the dynamics of the disclination line formed along the waveguide axis with increase or decrease in supply voltage. Finally, a description of the successful demonstration of UV-written single channels, y-splitters, and Bragg gratings into a novel flat fibre substrate is provided. Utilising a series of Bragg gratings enabled assessment of the core layer uniformity and birefringence.
34
Ross, Susan E. "DEVELOPMENT OF SPECTROELECTROCHEMICAL WAVEGUIDE SENSORS." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin971364855.
Full text
35
Chang, Cheng-Chun. "Coupled-waveguide Fabry-Perot resonator." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10062009-020056/.
Full text
36
Sevim, Koray Sözüer H. Sami. "One dimensional photonic crystal waveguide/." [s.n.] [s.l.], 2004. http://library.iyte.edu.tr/tezler/master/fizik/T000446.pdf.
Full text
37
Pathak, Shantanu. "Resonant optical waveguide biosensor characterization." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3792.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains viii, 109 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 107-109).
38
Sandhu, Muhammad Yameen. "Monolithic integrated ceramic waveguide filters." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7489/.
Full textAbstract:
Design techniques for a new class of monolithic integrated high permittivity ceramic rectangular waveguide microwave filters are presented in this thesis. These filters enable a size reduction of 50 % as compared to air filled coaxial resonator filters with the same unloaded Q-factor. Initially, an integrated ceramic rectangular waveguide resonator structure is investigated. It consists of a metal plated high permittivity ceramic rectangular block with Q-factor comparable to transverse electromagnetic (TEM) coaxial resonator but in a much miniaturised volume with good out of band spurious performance. The three dimensional finite element method (FEM) electromagnetic solver HFSSTM is used to analyse the resonant modes, Q-factor and field patterns of the ceramic waveguide resonator. High performance Chebyshev and generalised Chebyshev monolithic integrated ceramic rectangular waveguide filters are designed to meet the stringent electrical requirement for cellular radio base station. Inter-resonator couplings are achieved by placing various through and blind holes in the broad dimension of the waveguide. In the generalised chebyshev filter, both negative and positive cross couplings are introduced to achieve transmission zeros on both sides of the passband. Metal tuning screws are added to the generalised chebyshev design to correct any practical imperfections. The ceramic waveguide filters are excited through coaxial probes placed at the centre of the broad wall of the external resonators. An integrated ceramic rectangular waveguide diplexer design is also presented to be used at mobile base station front end to replace an existing TEM diplexer without degrading electrical performance in a much miniaturised volume. The both filters and the common junction of the diplexer consist of single metal coated ceramic block with various blind and through holes to realize a complex coupling scheme. Finally a low pass ceramic corrugated waveguide filter design is presented to be used along with diplexer at cellular base station to achieve very wide spurious free out of band bandwidth. The miniaturisation techniques discussed in this thesis will provide overall cost reduction for cellular communication systems requiring low loss narrowband bandpass filters.
39
GIBBONS, WAYNE MICHAEL. "ALL-OPTICAL NONLINEAR WAVEGUIDE DEVICES." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184212.
Full textAbstract:
The properties of all-optical nonlinear waveguide devices are investigated. In particular, the nonlinear directional coupler (NLDC) and nonlinear Mach-Zehnder interferometer (NLMZ) are analyzed using perturbation theory. The perturbation theory provides differential equations that describe the amplitude of the waveguide modes as a function of the propagation distance. To be practical, these waveguide devices require nonlinear phase shifts of π or more. Therefore, the theoretical investigation of these devices emphasizes their fabrication in bulk and multiple-quantum-well (MQW) gallium arsenide (GaAs). For the first time, absorption, carrier diffusion, and thermal effects are included in the theoretical investigation of the NLMZ and NLDC. The nonlinear dependence of the coupling terms, which has been neglected in all previous work, is shown to be significant for semiconductor based NLDC's. The effects of carrier diffusion on the nonlinear response of a GaAs waveguide is demonstrated using a self-consistent numerical method. The effects are heavily dependent on the waveguide geometry, and, therefore, should be included in the analysis of nonlinear semiconductor waveguide devices. However, if the diffusion length is large compared to the mode width, carrier diffusion simplifies the investigation since the nonlinear absorption and index change are uniform across the mode. This important conclusion is used in the models for the NLMZ and NLDC. The theoretical models predict the NLMZ and NLDC should work in bulk and MQW GaAs. To demonstrate that the required nonlinear phase shifts for the NLMZ and NLDC are indeed possible in bulk and MQW GaAs, the first experimental observation of electronic optical bistability in a MQW GaAs strip-loaded waveguide is recounted. This original research illustrated that phase shifts in excess of 2π are possible in MQW GaAs waveguides and, therefore, the future of all-optical waveguide devices in semiconductors is optimistic.
40
Wu, Liang. "Substrate integrated waveguide antenna applications." Thesis, University of Kent, 2015. https://kar.kent.ac.uk/50526/.
Full textAbstract:
The research objective of this thesis is to provide a better solution for signal interference and reduce the size of waveguide antenna. The background investigations of different waveguide fabrication technologies and switch control methods are detailed in the introductory part of this thesis. Several novel substrate integrated waveguide (SIW) antennas for different purpose are demonstrated in the body of the thesis. The designs are mainly divided into two kinds. The first focuses on the switch beam SIW antennas working at 2.4 GHz frequency band. Compared to the corresponding waveguide antennas of multiple-input and multiple-output (MIMO), phased array and switch beam, the proposed SIW antennas have advantages in compact size, easy fabrication and high gain. By DC biasing the surface mounted PIN diodes, the waveguide slots radiate at diode-off state of reverse bias, and are shielded at diode-on state of forward bias. Based on different requirement, the SIW antennas can achieve two-direction, four-direction and six-direction transmission. The gain can be easily changed by extending the size of reflector walls. The second focuses on reducing the volume of SIW antennas, working at 5 GHz frequency band. A new folded SIW antenna is introduced. By folded the antenna front end part to second layer, the SIW antenna reduces the total length by the size of one-quarter guided wavelength. This folded antenna can radiate either monopole mode or dipole mode, based on the metal surface area. Another two new SIW antennas reduce the total length by directly cutting the front-end part at the slot center. By utilized the intrinsic coupling radiation, the SIW antennas use two half-length slots at different broad-wall plane to achieve 360 degree propagation and wide-band end-fire radiation.
41
Sheel, Soumya. "Refinements to the design of waveguide slot arrays." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/131880/1/Soumya_Sheel_Thesis.pdf.
Full textAbstract:
Existing design techniques for waveguide slot arrays have certain limitations. This doctoral thesis presents a detailed mathematical derivation to account for higher-order coupling between main line slots and neighbouring radiating slots. New expressions are derived for the coupling slot equivalent impedance that accommodate phase differences between scattering parameters and higher-order coupling. The thesis also presents a design method that accounts for arbitrary levels of waveguide loss, and one that takes asymmetry of slot fields into account. In addition, a new single-layer feed structure capable of providing arbitrary complex power split ratios to variable branch line impedance is proposed.
42
Ergül, Adem. "Fabrication and Characterization of Superconductive Coplanar Waveguide Resonators : Fabrication and Characterization of Superconductive Coplanar Waveguide Resonators." Licentiate thesis, KTH, Applied Physics, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10419.
Full textAbstract:
The objective of this thesis is to evaluate a generic process for fabrication and characterization of the Superconductive coplanar waveguide (CPW) resonators. Superconductive CPW resonators with various lengths and shapes are designed to investigate their electrical and magnetic properties as well as resonance properties and sensitivities. In the first part of thesis, two different models are introduced in order to estimate the nonlinear kinetic inductance of a superconducting CPW resonator. The first model is based on Bean critical-state model and the second one is based on current dependence of London penetration depth. The existence of a shift in resonant frequency of Superconductive CPW resonator caused by a non-linear kinetic inductance is also shown experimentally. Simulations were carried out to estimate the nonlinear kinetic inductance due to the self- induced magnetic field penetration.
The rest of the thesis is concerned with development of very smooth Aluminum (Al) thin films with RMS (Root Mean Square) roughness 1~nm and CAD (Computer Aid Design) of superconductive CPW resonators. Experimental investigation of a generic fabrication technique for superconductive CPW resonator is carried out. Many resonators are fabricated with different design parameters, such as centerline or gap width, film thickness and gap capacitors length. The fabrication process is described in detail. Electron Beam Lithography is used to fabricate Nb and Al CPW resonators which are coupled to outer conductors via gap capacitors. We have fabricated GHz frequency CPW resonators with quality factors, Q up 5X10^5.
43
Wang, Qing. "Single-Frequency and Mode-Locked Glass Waveguide Lasers and Fiber-Optic Waveguide Resonators for Optical Communications." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/195101.
Full textAbstract:
Single-frequency and mode-locked silver film ion-exchanged glass waveguide lasers as well as all-optical clock recovery based on birefringent fiber resonators have been experimentally and theoretically studied. The theory, modeling and fabrication process of silver film ion-exchange techniques, have been discussed and presented.The UV-written gratings on both IOG-1 active and passive glass have been studied. For the first time, with a high quality narrowband grating UV-printed on the passive section of a hybrid glass, a DBR waveguide single-frequency laser is demonstrated with the linewidth less than 1 MHz and the output power of 9 mW.Novel saturable absorbers based on a fiber taper embedded in carbon nanotubes (CNTs)/polymer composite were demonstrated. The saturable absorbers were utilized to build mode-locked fiber lasers, which were studied experimentally. A mode-locked ring laser utilizing an Er-Yb-codoped glass waveguide as the gain medium was also demonstrated. In addition, short cavity mode-locked waveguide lasers with CNTs film on the top were theoretically investigated, which shows a short cavity mode-locked waveguide laser is very promising.A new concept to perform multi-channel multi-rate all-optical clock recovery based on birefringent fiber-optic waveguide resonators was discussed. The concept has been advanced to polarization-insensitive operation. The experimental results, obtained as a proof-of-concept, agree well with numerical simulations.
44
Lombardo, David. "Design and Fabrication of Suspended Waveguides With Photonic Grating Structures." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1591796311145344.
Full text
45
Ainsworth, Joseph. "A numerical model of the propagation characteristics of multi-layer ridged substrate integrated waveguide." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/a-numerical-model-of-the-propagation-characteristics-of-multilayer-ridged-substrate-integrated-waveguide(23c69a19-694c-41c6-8870-5c09e5734362).html.
Full textAbstract:
A transmission line format is presented which takes the form of a Multilayer Ridged Substrate Integrated Waveguide, for which signal energy is transmitted within standard PCB substrates, within a wave-guiding structure formed from conducting tracks in the horizontal plane and arrays of through-plated vias in the vertical plane. The Substrate Integrated Waveguide (SIW) is a recent development into which research is so far concentrated on single-layer rectangular variants which, like traditional rectangular waveguide, are amenable to analytic computation of the cutoff eigenvalues. Recent publications have offered empirically-derived relationships with which a Substrate Integrated Waveguide can be analysed by equivalence of the horizontal dimensions with a conventional waveguide, allowing such structures to be designed with minimal effort. We propose a ridged form of this structure, in which multiple PCB layers are stacked to obtain the desired height and the published equivalent width is used to obtain the horizontal dimensions. The proposed structure combines the increased bandwidth of ridged waveguide with SIW’s greatly reduced cost of manufacture and integration, relative to conventional waveguide, and improved power handling capacity and loss susceptibility relative to microstrip. Ridged variants have not yet been studied in the literature, however, in part because the eigenspectrum can not be obtained analytically. We thus present a semi-analytical software model with which to synthesise and analyse the cutoff spectrum in ridged Substrate Integrated Waveguide, verified by comparison with analytical solutions, where they exist, simulation in finite-element software and a physical prototype. Agreement with simulated and measured results is within 1 % in certain subsets of the parameter space and 11 % generally, and individual results are returned in times of the order of seconds. We use the model to analyse the relationship between geometry and frequency response, constructing an approximating function for the early modes which is significantly faster, such that think it can be used for first-pass optimisation. A range of optimal parameters are presented which maximise bandwidth within anticipated planar geometric constraints, and typical design scenarios are explored.
46
Roncone, Ronald Louis. "An experimental and theoretical investigation of waveguide scatter, with applications to solution-deposited silica-titania planar waveguides." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/186042.
Full textAbstract:
A theoretical and experimental investigation of scatter from surface roughness and core refractive index fluctuations in planar waveguides was performed, with an emphasis placed on applications in solution-deposited SiO₂-TiO₂ (silica titania) planar waveguiding systems. A perturbation theory was used to model TE₀ mode scattering from surface and volume microstructure, and to predict attenuation when provided with the necessary waveguide and scattering parameters. Final forms for the equations predicting surface and volume scatter losses into the cover and substrate regions of the waveguides were provided. The rather complex perturbation theory model of surface scatter was compared to a very simple, intuitive model based on the Rayleigh criterion. The two models were shown to predict surface induced attenuation values which were in very close agreement when the guided mode propagation angle approached 90°. Thus, the simple model was shown to be adequate for predicting TE₀ mode surface scattering losses for waveguides which were very thick, and/or possessed a low refractive index. Considerable emphasis was placed on providing a simple, physical picture of guided mode scattering, utilizing rays to represent the scattered light. Following the development of this technique, it was utilized to explain the origins of interference peaks in surface scattered radiation at certain values of film thickness. Solution chemistry and processing methodologies for 50:50 mol% and 35:65 mol% SiO₂-TiO₂ sol-gel films, yielding high quality, amorphous, glass waveguides, were discussed. Attenuation in the 50:50 mol% films was 1-2 dB/cm, while attenuation in the 35:65 mol% films was 0.3-0.5 dB/cm, at λ = 0.6328 μm. Absorption in these films was negligible. Waveguide losses were measured by transferring the scattered streak to a remote image plane (using a coherent fiber bundle) and scanning it using an automated, stepper-motor controlled, apertured photomultiplier tube. Testing and calibration techniques were described in detail. We found that surface-induced scattering was the dominant loss mechanism in the 35:65 mol% SiO₂-TiO₂ films. Surface roughnesses of the sol-gel films, measured using Atomic Force Microscopy, ranged from about 2-5 A rms, with correlation lengths from about 0.05-0.75 μm.
47
Rabady, Rabi Ibrahim. "Waveguide grating mirror for laser resonators." Connect to online resource - WSU on-site and authorized users, 2003.
Find full text
48
Dogan, Doganay. "Dual Polarized Slotted Waveguide Array Antenna." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613016/index.pdf.
Full textAbstract:
An X band dual polarized slotted waveguide antenna array is designed with very high polarization purity for both horizontal and vertical polarizations. Horizontally polarized radiators are designed using a novel non-inclined edge wall slots whereas the vertically polarized slots are implemented using broad wall slots opened on baffled single ridge rectangular waveguides. Electromagnetic model based on an infinite array unit cell approach is introduced to characterize the slots used in the array. 20 by 10 element planar array of these slots is manufactured and radiation fields are measured. The measurement results of this array are in very good accordance with the simulation results. The dual polarized antenna possesses a low sidelobe level of -35 dB and is able to scan a sector of ±35 degrees in elevation. It also has a usable bandwidth of 600 MHz.
49
Mehrotra, Sandeep. "Analysis of optical waveguide fabrication processes." Ohio : Ohio University, 1986. http://www.ohiolink.edu/etd/view.cgi?ohiou1183140884.
Full text
50
Smith, Nathan. "Substrate integrated waveguide circuits and systems." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=92388.
Full textAbstract:
This thesis investigates substrate integrated waveguide (SIW) based interconnects, components, and systems. SIWs are high performance broadband interconnects with excellent immunity to electromagnetic interference and suitable for use in microwave and millimetre-wave electronics, as well as wideband systems. They are very low-cost in comparison to the classic milled metallic waveguides as they may be developed using inexpensive printed circuit board (PCB) fabrication techniques. In this thesis, the interconnect design is studied by investigating the modes supported by SIW using fullwave simulations. Also, SIW transitions, as well as miniaturization methods to decrease the waveguide footprint are evaluated. Next, a miniaturized Wilkinson SIW power divider is developed exhibiting excellent isolation of up to 40dB between its output ports. Another SIW component investigated in this thesis is an SIW cavity resonator. A circular SIW cavity resonator fed by a microstrip line and via probe through an opening on the top cavity wall is designed. The aperture on the top wall creates a radiating folded slot and measurements show a gain of 7.76dB for this cavity-backed antenna at 16.79GHz. The antenna exhibits a bandwidth of 250MHz (return loss > 10dB). With this resonator, a microwave oscillator is designed to produce a 10dBm tone. Measurements of the fabricated oscillator demonstrate a low phase noise of -82dBc/Hz. Finally, a new SIW component, i.e. tapered SIW reflector, is designed to counteract the dispersive behavior of an SIW interconnect near cutoff. Two dispersion equalization systems are implemented using either a circulator or a coupler to route the compensated reflected signal. The systems are tested when a 1Gbps pseudo-random binary signal is up-converted to 10.7GHz and launched into the SIW interconnect. Observation of the compensated output eye-diagrams reveals achievement of a lower distortion in the highly dispersive band just above the cutoff frequency.Cette thèse examine des interconnexions, des composantes et des systèmes basés sur des guides d'ondes intégrés au substrat (GIS). Les GIS sont des interconnexions de haute performance à large bande qui possèdent d'excellentes caractéristiques d'immunité contre les interférences électromagnétiques et qu'on pourrait utiliser dans des systèmes microondes et des circuits d'ondes millimétriques. Le coût des GIS est très faible comparativement à celui des guides d'ondes métalliques communs, car leur fabrication utilise des techniques peu coûteuses de production de cartes de circuits imprimés. Cette thèse étudie, au moyen de simulations à onde entière, le design de l'interconnexion et les modes supportés par le GIS. De plus, la thèse évalue les transitions des GIS ainsi que les méthodes de miniaturisation visant à diminuer l'empreinte du guide d'onde. Ensuite, la thèse expose le développement d'un répartiteur de puissance GIS Wilkinson qui possède d'excellentes propriétés isolantes allant jusqu'à 40dB entre les bornes de sortie. La thèse examine aussi une autre composante GIS: un résonateur à cavité GIS. La thèse décrit la conception d'un résonateur à cavité GIS qui est alimenté par une ligne microbande et une sonde passées par une aperture sur le mur supérieur de la cavité. L'aperture dans le mur supérieur crée une encoche plissée rayonnante, et des mesures ont révélé un gain de 7,76dB pour l'antenne adossée d'une cavité de 16,79 GHz. L'antenne possède une bande passante de 250MHz (perte de réflexion > 10dB). En plus de ce résonateur, un oscillateur micro-onde est conçu pour produire une tonalité de 10dBm. Les mesures de l'oscillateur fabriqué montrent un faible bruit de phase de -82dBc/Hz. Enfin, une nouvelle composante de GIS (un réflecteur effilé) est conçue pour compenser la caractéristique dispersive d'une interconnexion GIS près de la fréquence de coupure. Deux systèmes de correction de la disp