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Dissertations / Theses on the topic 'Diffraction gratings'

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Published: 4 June 2021
Last updated: 28 July 2024

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1

Walsh, Sheridan John T. P. "Diffraction by volume gratings." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303660.

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2

Watson, Andre James. "Diffraction gratings in ray tracing." Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1464665.

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Thesis (M.S.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed July 7, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 66-67).
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3

DeSandre, Lewis Francis. "Extinction theorem analysis of diffraction anomalies in overcoated-gratings." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184853.

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A rigorous analysis based upon the extinction theorem is presented to study anomalous resonance effects from single- and multilayer-overcoated, low-efficiency diffraction gratings. Anomalously high diffraction efficiency at resonance results from the coupling of the incident beam into guided waves that can be propagated within the composite structure. Both the traditional characteristic matrix technique and a recursive or R-matrix propagation technique are presented. The R-matrix propagation algorithm was found to be stable numerically, and computational results agree favorably with both experimental and other theoretical work. Numerical results are presented in order to investigate the influence of certain parameters (i.e., groove depth and shape and the number of high- and low-index overlayers) on the diffraction efficiency at resonance. In this analysis, a wavelength of 0.6328 μm and grating period of 0.7 μm were chosen so that only a -1 diffracted order other than the specular is reflected from the gratings. Perfect transfer of the grating relief to the film boundaries does not occur in all instances; it depends on the grating and film characteristics together with the conditions during deposition. Investigated in this work is the effect of nonreplication of the grating profile at film interfaces on anomalous diffraction; a transition from trapezoidal profile at the grating substrate to a rounded relief at the top surface of the multilayer structure is assumed. For the cases studied, it was found that nonreplication has the effect of reducing the strength of the resonance outcoupling. Finally, experimental results on anomalous resonance effects for multilayer-coated gratings are presented. Good agreement with computational results was attained.
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4

Li, Lifeng. "Application of diffraction grating theory to analysis and fabrication of waveguide gratings." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184388.

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This dissertation includes three separate studies of related waveguide grating phenomena. These studies deal with a numerical improvement of the integral method of diffraction grating theory, the theoretical analysis of waveguide gratings, and fabrication techniques for photoresist grating masks. The first topic addresses the acceleration of the convergence of the integral kernels. To improve the performance of the integral method for calculating diffraction grating efficiencies, the convergence of the integral kernels is studied. A nonlinear sequence transformation, Levin's u-transformation, is successfully applied to accelerate the convergence of the integral kernels. The computer execution time saving is significant. The application details and many numerical examples are given. The second subject is the ray optics theory of waveguide grating analysis. To establish a linkage between the analysis of diffraction gratings and the analysis of waveguide gratings, a new rigorous ray optics theory is developed. It takes into account phase changes on diffraction, multiple diffraction processes, depletion of the incident guided wave, and lateral shifts. A general characteristic equation that determines the waveguide grating attenuation (coupling) coefficient is derived. The symmetry properties of grating diffraction are applied to waveguide grating analysis for the first time. Lateral shifts of optical rays at a periodically corrugated interface similar to the Goos-Haenchen shift at a planar interface are suggested. The third subject is the in situ control of the development of photoresist grating masks. The existing method for monitoring and modeling photoresist grating development are modified and extended to monitoring and modeling photoresist grating mask development. Experimental examples, detailed theoretical considerations, and computer simulations are presented.
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5

Watts, Richard Adrian. "The optical response of metallic diffraction gratings." Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361343.

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6

Chang, Chih-Hao 1980. "Fabrication of extremely smooth blazed diffraction gratings." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/27056.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (p. 103-106).
High efficiency diffraction gratings are important in a variety of applications, such as optical telecommunications, lithography, and spectroscopy. Special interest has been placed on blazed diffraction gratings for their ability to enhance diffraction intensity at the specular reflection angle off the blazed facets. In this thesis I will report a novel process for fabricating extremely smooth blazed diffraction gratings with 200 nm-period. The blazed grating is fabricated using interference lithography and anisotropic etching, then replicated using nanoimprint lithography. This process was developed for fabricating the off-plane blazed diffraction gratings for the NASA Constellation-X x-ray space telescope. In order for x-rays to reflect effectively through grazing incidence reflection, the gratings will be coated with high atomic number materials, such as gold. Deposition of thin metal film often develops residual stress that adds out-of-plane distortion. In this thesis the out-of-plane distortions due to thin metal films are analyzed using wavefront aberration functions known as the Zernike polynomials. The thin film stress is proved to be linearly related to the change of the Z₂₁ Zernike coefficient. The anisotropic material properties of silicon are taken into account in the derivation, and a prediction of lattice dependent distortion is proposed.
by Chih-Hao Chang.
S.M.
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7

Cai, Li-He. "Experimental investigation of some conducting crossed gratings." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25056.

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The properties of a crossed grating of square pyramids and a crossed grating with hemispherical cavities to eliminate specular reflection from a conducting surface are studied experimentally. Measurements were made in the microwave range of 35 GHz. The best performance is that 99.94% of the power of a TM-polarized incident wave can be scattered into a single spectral order by a pyramidal crossed grating, while for TE polarization the reduction in specular reflection can be as high as 98%. Anti-reflection properties of a crossed grating with hemispherical cavities near normal incidence are also observed. Comparison between the behavior of triangular and pyramidal gratings of the same profile is made. Effects of the profile parameters are investigated. Basically the experimental results agree with the theoretical predictions. This investigation provides a set of experimental data to assist further numerical study.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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8

Brundrett, David L. "Analysis, design, and applications of subwavelength diffraction gratings." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/15370.

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9

Napier, Bruce. "Writing of holographic diffraction gratings of unrestricted length." Thesis, De Montfort University, 1998. http://hdl.handle.net/2086/5855.

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10

Pierce, Jordan. "Holographic Sculpting of Electron Beams with Diffraction Gratings." Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24182.

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Electron microscopes offer scientists an invaluable tool in probing matter at a very small scale. Rapid advancements over the past several decades has allowed electron microscopes to routinely image samples at the atomic scale. These advancements have been in all aspects of electron microscope design – such as more stable control voltages and currents, brighter and more coherent sources, beam aberration correction, and direct electron detectors, to name a few. One very recent advancement is in shaping the electron beam to provide an almost arbitrary set of possible beam profiles. Following the demonstration of electron vortex beams in 2010, there has been a surge of interest in the potential shaping electron beams. Utilizing holographic electron diffraction gratings, an almost arbitrary set of electron beams can be generated. These diffraction gratings are challenging to create due their tiny size and the precision with which they must be fabricated. We present a comprehensive study on the fabrication and design of electron diffraction gratings with the aim of being able to produce optimal gratings that result in bright, well separated beams which closely match a desired beam profile. We have developed and optimized fabrication of these gratings with focused ion beam milling, and have been able to use the fabricated gratings in a number of important experiments. These electron diffraction gratings have allowed us to perform various experiments such as aberration correction, electron helical dichroism, advanced phase-contrast imaging, and multi-beam interferometric techniques. Holographic beam shaping will continue to be an important tool for electron microscopists.
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11

Bangert, D. E. "Computational studies of gratings." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344034.

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12

Rockward, Willie Samuel. "Crossed phase gratings using diffractive optical elements." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/31038.

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13

Harris, Jonathan Blair. "Modelling the optical response of multilayered gratings containing liquid crytals." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337766.

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14

Schmittdiel, Michael C. "Active control of a diffraction grating interferometer for microscale devices." Thesis, Available online, Georgia Institute of Technology, 2005, 2004. http://etd.gatech.edu/theses/available/etd-07102004-164021/.

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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.
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15

Garnier, Jérôme. "Polymer electrochromism and surface plasmons combined on metallic diffraction gratings." Thesis, Linköping University, Department of Science and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11522.

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All conducting polymers are potentially electrochromic, owing to the injection of charge carriers that changes their electronic structure and results in a shift of their optical absorption towards higher wavelengths. PEDOT-PSS and PEDOT-S are very promising materials in terms of electrochromic properties, due to the good contrast existing between their doped and undoped forms. However this contrast has to be enhanced in order to design more efficient electrochromic devices, and new solutions should thus be found in order to solve this issue.

Surface plasmons are described as electromagnetic waves propagating along the surface between a dielectric and a metal. Coupled to an incident radiation, they create an energy loss in the light transmitted and reflected by the interface. When the metallic surface is periodically corrugated, this absorption phenomenon due to plasmonic resonance occurs at a specific wavelength that depends on several parameters, such as the incidence angle, the dielectric constants of the two media and the grating period. By coating metallic gratings with electrochromic polymers, we may thus be able to trigger a plasmonic absorption at a given wavelength and shift it upon reduction or oxidation of the material.

Electrochromic devices consisting of PEDOT-PSS or PEDOT-S spin-deposited on gold and silver gratings were investigated by UV-visible reflectance measurements. The periodically corrugated structures were reproduced from commercial gratings by soft nanolithography and were analyzed by AFM. Some electrochromic cells exhibited new colors or a high shift of the plasmonic resonance upon redox switching of the polymer film. Depending on the step and the nature of the grating employed, this shift could reach 20 nm in the case of PEDOT-PSS and more than 100 nm for PEDOT-S. A theoretical model was found to predict the wavelength of plasmonic excitation and the orientation of the shift.

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16

Suleski, Thomas J. "The talbot effect : Fresnel diffraction of amplitude and phase gratings." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/29829.

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17

Barnes, Robert David Frazer. "Diffraction gratings as a platform for overlayer detection and representation." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319553.

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18

Bisaillon, Eric. "Distributed diffractive structures for micro-optical systems." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103366.

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In modern communications systems, the components supporting wavelength division for increased density are rapidly becoming small compared with the wavelength of light being manipulated. As the size of these devices shrinks there comes a point when the features of interest become smaller than the wavelength and thereby the fundamental properties of light interaction with such structures change dramatically. In these structures and materials, resonances, effective properties, and band-gaps arise and offer designers a new realm of possibilities for the design of high quality factor resonators, filters and switches.
The study of structures comprising two different scales compared with the wavelength of light promises interesting optical possibilities for future devices. In these structures a subwavelength size feature is used in conjunction with a super-wavelength size feature. This thesis will show how the resulting optical behavior for such structures arises from the combination of the sub- and super-wavelength diffractive effects.
Two application examples of these two-scale devices will be studied: the distributed echelle grating and the subwavelength based Fabry-Perot cavity. Both of these applications can be thought, of as distributed diffractive structures, a structure in which diffraction and subwavelength scale interference combine to produce high efficiency and versatile new devices.
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19

Ehrlich, Jeffrey Ellis. "Nonlinear grating structures in indium antimonide waveguides." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184914.

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This dissertation describes various nonlinear grating coupling phenomena in InSb waveguides. InSb exhibits an opto-thermal, diffusive nonlinearity at 9.6μm. This nonlinearity strongly modifies the growth of a guided wave via the grating coupling of an incident, Gaussian signal. In particular, optical limiting and bistability in the coupled power were demonstrated for a detuned grating coupler. The limits on the detunings were also investigated. The experimental results showed qualitative agreement with a theory based upon a diffusive nonlinearity in the grating coupling process. Also demonstrated and theoretically explained was a new form of "butterfly" bistability in the output coupled signal from a nonlinear waveguide. In this situation, nonlinear interference effects in the substrate modified the proportion of power outcoupled into the cover and the substrate. The effects of a thermal nonlinearity on the response of a distributed feedback grating (DFB) were also studied. The DFB reflection response of an incident guided wave was modified either by varying the power of the incident guided wave or that of a second guided wave. Also, the effects of the DFB reflection were shown to enhance the bistable input grating coupling process by providing an additional feedback. This enhancement resulted in a smaller incident switching power required to obtain bistability in the input coupler.
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20

Cotter, Nicholas Paul Kyle. "Scattering matrix modelling of optical gratings." Thesis, University of Exeter, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300552.

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21

Kuo, Chai-Pei. "Characterization of photoinduced gratings in optical glass fibers." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184515.

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The properties of photo-induced gratings in germania doped glass fibers were studied. Permanent phase gratings in a fiber core were fabricated by the mixing of two contra propagating waves. Experiments are described and results are presented which show that the strength of a photoinduced grating is strongly dependent on the writing power as well as the laser writing wavelength. A rigorous development of linear coupled mode theory for the contra propagation geometry is given and used to model the experimentally observed grating responses as a function of fine tuning frequency of probing light. Measurements have been done of the amplitude and phase response of the grating structure and compared with theoretical models of uniform and chirped gratings. The theoretically predicted negative group velocity dispersion in fiber grating was observed interferometrically and described in detail. The nonlinear coupled mode theory has been fully implemented in a computer program and some numerical results are given in the second part of this thesis. The dynamics of a pulse propagating in the fiber grating is simulated and the results show its dependence on pulse energy, frequency detuning, and the type of grating geometry. A limitation is found in the dispersion property of a constant amplitude fiber grating so that the pulse compression ratio and the width of a compressible pulse is strictly limited to ≅250 picoseconds.
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22

Shi, Lei. "Tunable liquid crystal polarization gratings." [Kent, Ohio] : Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1258988951.

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Thesis (Ph.D.)--Kent State University, 2009.
Title from PDF t.p. (viewed Apr. 22, 2010). Advisor: Philip Bos. Keywords: Liquid crystal; beam steering; polarization gratings; diffraction efficiency; decentered microlens array. Includes bibliographical references (p. 216-219).
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23

D'Alberto, Tiffanie Gabrielle. "Long-Period Gratings as Immuno-Diagnostic biosensors." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/30480.

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This research presents a novel biosensor which utilizes the refractive index sensitivity of a fiber optic long-period grating. The long period grating couples light from the forward propagating guided core mode of a single-mode fiber into discrete circularly symmetric cladding modes. Due to imperfections in the cladding surface, loss bands are seen in the transmission spectrum corresponding to the coupled wavelengths. Based on the phase-matching condition between the coupling and coupled modes, the loss bands shift with changes in the refractive index of the surrounding medium. The grating surface is chemically treated to covalently bond antibody to the cladding of the sensor. Treatment with the proper antigen increases the effective index seen by the cladding modes and affects the placement of the loss bands. This sensor demonstrates specific antigen binding capacity with loss band shifts of 10 nm or more. The device offers several advantages over the widely used Enzyme-Linked Immuno-Sorbent Assays. Diagnostic applications can be expanded beyond the tests presented here.
Master of Science
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24

Gushchin, Ivan. "The modal method : a reference method for modeling of the 2D metal diffraction gratings." Thesis, Saint-Etienne, 2011. http://www.theses.fr/2011STET4010/document.

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Les éléments de diffraction sont largement utilisés aujourd'hui dans un nombre grandissant d'applications grâce à la progression des technologies de microstructuration dans le sillage de la micro-électronique. Pour un design optimal de ces éléments, des méthodes de modélisation précises sont nécessaires. Plusieurs méthodes ont été développées et sont utilisées avec succès pour des réseaux de diffraction unidimensionnel de différents types. Cependant, les méthodes existantes pour les réseaux deux dimensionnel ne couvrent pas tous types de structures possibles. En particulier, le calcul de l'efficacité de diffraction sur les réseaux métalliques à deux dimensionnel avec parois verticales représente encore une grosse difficulté pour les méthodes existantes. Le présent travail a pour objectif le développement d'une méthode exacte de calcul de l'efficacité de diffraction de tels réseaux qui puisse servir de référence. La méthode modale développée ici - dénommée ,,true-mode" en anglais - exprime le champ électromagnétique sur la base des vrais modes électromagnétiques satisfaisant les conditions limites de la structure 2D à la différence d'une méthode modale où les modes sont ceux d'une structure approchée obtenue, par exemple, par développement de Fourier. L'identification et la représentation de ces vrais modes à deux dimensions restait à faire et ce n'est pas le moindre des résultats du présent travail que d'y avoir conduit. Les expressions pour la construction du champ sont données avec des exemples de résultats concrets. Sont aussi fournies les équations pour le calcul des intégrales de recouvrement et des éléments de la matrice de diffusion
Diffractive elements are widely used in many applications now as the microstructuring technologies are making fast progresses in the wake of microelectronics. For the optimization of these elements accurate modeling methods are needed. There exists well-developed and widely used methods for one-dimensional diffraction gratings of different types. However, the methods available for solving two-dimensional periodic structures do not cover all possible grating types. The development of a method to calculate the diffraction efficiency of two dimensional metallic gratings represents the objective of this work. The one-dimensional true-mode method is based on the representation of the field inside the periodic element as a superposition of particular solutions, each one of them satisfying exactly the boundary conditions. In the developed method for the two-dimensional gratings the representation of the field within the grating in such way is used. In the present work, the existing modal methods for one-dimensional gratings can be used as the basis for the construction of the modal field distribution functions within two-dimensional gratings. The modal function distributions allow to calculate the overlap integrals of the fields outside the grating with those within the structure. The transition matrix coefficients are formed on the basis of these integrals. The final stage is the calculation of the scattering matrix based on two transition matrices. The equations for the field reconstruction are provided and accompanied by examples of results. Further equations used to calculate the overlap integrals and scattering matrix coefficients are provided
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25

Wanstall, Nicholas Peter. "Modelling the electromagnetic response of deep, blazed and overhanging gratings." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288019.

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26

Aslund, Mattas L. "Bragg grating interference devices." Thesis, The University of Sydney, 2004. https://hdl.handle.net/2123/28157.

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This thesis is about novel components designed to enable low-cost optical fiber networks. These networks constitute the global backbone of the in— ternet and all other telecommunication. However, the available technologies are much to expensive to be considered for home-users, so the optical fiber networks only reach as far as the substations half—way to the home—user. Op— tical fiber networks all the way to the home—users is potentially an immense market, and there is a large interest from the industry in novel enabling technologies.
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27

Barrett, Christopher John. "Laser inscription of holographic diffraction gratings in thin films of azo polymers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/nq22445.pdf.

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28

Abd-Eldayem, Ibrahim Ali Mahmoud. "Design and microwave modelling of optical diffraction gratings having shaped scanned beams." Thesis, Cranfield University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261162.

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29

Hutchinson, Glenn David. "Direct laser fabrication of diffraction gratings on polymer thin films and waveguides." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2563.

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Thesis (M.S.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Dept. of Electrical and Computer Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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30

Andrew, Piers. "Molecular fluorescence near metallic interfaces." Thesis, University of Exeter, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265270.

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31

Maikisch, Jonathan Stephen. "Compact silicon diffractive sensor: design, fabrication, and functional demonstration." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45882.

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The primary objective of the presented research is to develop a class of integrated compact silicon diffractive sensors (CSDS) based on in-plane diffraction gratings. This class of sensors uses a silicon-on-insulator (SOI) substrate to limit costs, exploit established fabrication processes, enable integration of supporting electronics, and use the well-understood telecommunications wavelength of 1.55µm. Sensing is achieved by combining constant-diffraction-efficiency and highly-angularly-selective in-plane resonance-domain diffraction gratings. Detection is based on the diffraction efficiency of the highly angularly selective grating. In this research, the design processes for the constant-diffraction-efficiency and the highly angularly selective gratings are detailed. Grating designs are optimized with rigorous coupled-wave analysis (RCWA) and simulated with finite-difference time-domain (FDTD) analysis. Fabrication results are presented for the CSDS gratings. An inductively coupled plasma (ICP) Bosch etch process enables grating fabrication to within one percent of designed values with nearly vertical sidewalls. Experimental results are presented for individual CSDS gratings, the prototype sensor, and a prototype linear sensor array. The results agree well with simulation. The linear sensor array prototype demonstrates the intrinsic splitting mechanism and forms the basis of a 2-D sensor array. Finally, a toluene sensor was functionally demonstrated. The proof-of-concept device includes a polymer immobilization layer and microfluidic delivery of toluene. Toluene concentrations as low as 100ppm are measured, corresponding to a refractive index change of 3x10⁻⁴ RIU.
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32

Doroshenko, V. O., N. P. Klimova, N. P. Stognii, and G. V. Sova. "Modeling the Electromagnetic Wave Diffraction on Conical Gratings Consisting of Zero-Thickness PEC Strips." Thesis, 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers, CAOL*2019, 2019. https://openarchive.nure.ua/handle/document/16297.

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The periodic gratings are effectively used for producing modern electronics and radio engineering equipment and complexes. The electromagnetic wave diffraction problem for cone gratings is considered. Impedance boundary conditions at cone structure are proposed. The problem of electromagnetic wave diffraction on cone gratings with imperfectly conducting strips is studied. Diagrams of electromagnetic field distribution are given
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33

Gushchin, Ivan. "La méthode modale : une méthode de référence pour la modélisation de réseaux de diffraction métalliques deux dimensionnel." Phd thesis, Université Jean Monnet - Saint-Etienne, 2011. http://tel.archives-ouvertes.fr/tel-00694044.

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Les éléments de diffraction sont largement utilises aujourd'hui dans un nombre grandissant d'applications grâce à la progression des technologies de micro-structuration dans le sillage de la microélectronique. Pour un design optimal de ces éléments, des méthodes de modélisation précises sont nécessaires. Plusieurs méthodes ont été développées et sont utilisées avec succès pour des réseaux de diffraction unidimensionnel de différents types. Cependant, les méthodes existantes pour les réseaux deux dimensionnel ne couvrent pas tous types de structures possibles. En particulier, le calcul de l'efficacité de diffraction sur les réseaux métalliques à deux dimensionnel avec parois verticales représente encore une grosse difficulté pour les méthodes existantes. Le présent travail a l'objectif le développement d'une méthode exacte de calcul de l'efficacité de diffraction de tels réseaux qui puisse servir de référence. La méthode modale développée ici - dénommée -true-mode" en anglais - exprime le champ électromagnétique sur la base des vrais modes électromagnétiques satisfaisant les conditions limites de la structure 2D à la différence d'une méthode modale où les modes sont ceux d'une structure approchée obtenue, par exemple, par développement de Fourier. L'identification et la représentation de ces vrais modes 'a deux dimensions restait 'a faire et ce n'est pas le moindre des résultats du présent travail que d'y avoir conduit. Les expressions pour la construction du champ sont données avec des exemples de résultats concrets. Sont aussi fournies les équations pour le calcul des intégrales de recouvrement et des éléments de la matrice de diffusion.
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34

Smith, Sean A. "Development of grating light reflection spectroscopy for chemical sensing applications /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/11592.

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35

Hamad, Mazen Lee. "Exploring and developing the instrumental aspects of grating light reflection spectroscopy /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8610.

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36

Anderson, Brian Benjamin. "Grating light reflection spectroscopy /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/8600.

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37

Smith, Michael Sean Dyck. "Application of the differential method to diffraction gratings that utilize total internal reflection facets." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0006/MQ32250.pdf.

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38

Schultz, Stephen M. "High efficiency volume grating coupler." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/16899.

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39

Urtiga, Lucas. "Long-period gratings in chalcogenide fibers." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27124/27124.pdf.

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40

Khalaf, Loay D. "Optimization of periodic devices using the finite element method." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/13758.

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41

Ang, Tze Wei. "Optical grating couplers in silicon-on-insulator." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843726/.

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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.
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42

Aesa, Abdulsattar Ahmad. "Characterisation of laser processed bio-compatible materials and the realisation of electro optical diffraction gratings." Thesis, University of Hull, 2018. http://hydra.hull.ac.uk/resources/hull:16591.

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Laser processing methods using excimer lasers have become very attractive for processing materials and the fabrication of micro and nano optical components. Diffraction gratings are used in a wide range of applications and require different fabrication methods. These components can be fabricated from a variety of biocompatible polymers. In this work, an Argon Fluoride (ArF) excimer laser operating at a wavelength of 193 nm has been used to process chitosan and agarose substrates. These materials have been characterised for differing laser processing conditions. Diffraction gratings and component demonstrators have been realised using Laser Direct writing (LDW) and nanoimprinting lithography (NIL). Characterisation of the ArF 193 nm laser work involves ablation threshold, optical absorption measurements and quantification of structural and morphological changes. This results can be used to identify the ideal laser fluence to be used for the production of a diffraction grating and similar optical components fabricated from chitosan. An ablation threshold of chitosan at 193 nm wavelength has been measured as 85 mJcm−2 and an optical absorption coefficient of 3×103 cm−1. A diffraction grating structure, measuring 12 μm, was generated in biocompatible materials films; chitosan and agarose, using a laser processing method. The results showed that the interaction between the laser and these materials can potentially open the pathway for a wide range of practical, real world applications such as optical and biomedical applications. Diffraction gratings with a feature size of 1 μm were successfully formed on the biocompatible material free standing films using a NIL technique. Microstructure cross grating patterning made of chitosan and agarose have been fabricated by ArF excimer laser processing using a mask projection ablation technique. Temperature rise calculations have been carried out by COMSOLTM Multi-Physics v5.3 using a Finite Element Method (FEM), to predict the temperature rise during laser ablation processing of chitosan and agarose. In addition, COMSOLTM Multi-physics v5.3 has been used to simulate the electric field in the vicinity of a diffraction grating that is illuminated with light from a HeNe laser emitting at a wavelength of 632.8 nm. The final experimental work investigated the possibility of realising 5CB liquid crystal doped chitosan diffraction gratings doped with Sudan Black B (SBB) dye to enhance the absorption properties at 632.8 nm. Diffraction gratings was fabricated using two intersecting beams from a HeNe laser. Polymer Dispersed Liquid Crystal (PDLC) chitosan doped with 5CB and SBB dye diffraction gratings were experimentally characterised.
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43

Meng, Xianqin. "Design and fabrication of photonic crystals and diffraction gratings for ultra thin film Si solar cells." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00780711.

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Ce travail de thèse est consacré au piégeage de la lumière par des cristaux photoniques(CP) et des réseaux de diffraction. L'objectif consiste à intégrer de telles structures dans des cellules solaires à couches ultra-minces de silicium, afin d'augmenter leur rendement de conversion. Nous avons conçu et optimisé des cellules solaires en silicium cristallin (c-Si) assistées par les CP, grâce à la méthode FDTD (Finite Difference Time Domain). En gravant un CP 2Ddans la couche active de silicium, l'absorption intégrée sur l'ensemble du spectre est augmentée de 50%. Cette amélioration est atteinte en combinant des modes de Bloch lent et des résonances Fabry-Perot. Afin de réaliser de telles cellules solaires, nous avons développé une filière technologique combinant insolation holographique, gravure ionique réactive et gravure ICP (Inductively Coupled Plasma). Nous avons étudié l'influence des paramètres de ces procédés sur la structuration réalisée. Enfin, les caractéristiques optiques et électriques de ces objets ont été mesurées par nos collaborateurs de l'IMEC, en Belgique. Les mesures d'absorption sont en bon accord avec les prédictions théoriques. De plus, l'absorption intégrée est peu sensible à l'angle d'incidence de la lumière solaire. La cellule solaire structurée comme un CP 2D présente finalement un courant de court-circuit d'environ 15mA/cm², soit20% plus élevé que dans le cas de la cellule de référence. Par ailleurs, nous avons conçu une cellule solaire en c-Si plus complexe, intégrant des réseaux de diffraction avant et arrière. L'absorption aux grandes longueurs d'onde est augmentée du fait de la période élevée (750 nm) du réseau arrière, tandis que la réflexion en face avant est diminuée du fait de la faible période (250 nm) du réseau avant. Nous avons prédit une augmentation du courant de court-circuit jusqu'à 30m A/cm² pour ce dispositif, en comparaison avec la valeur de 18 mA/cm² correspondant à la cellule de référence non structurée. Ces résultats sont première étape vers le développement de futures générations de cellules solaires assistées par des cristaux photoniques et des réseaux de diffraction.
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44

Harper, Kevin Randolph. "Theory, Design, and Fabrication of Diffractive Grating Coupler for Slab Waveguide." Diss., CLICK HERE for online access, 2003. http://contentdm.lib.byu.edu/ETD/image/etd281.pdf.

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45

Blasiak, Thomas C. "Modeling holographic grating imaging systems using the angular spectrum propagation method /." Link to online version, 2006. https://ritdml.rit.edu/dspace/handle/1850/2294.

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46

Goodman, Steven John. "Resonances of scattering in non-uniform and anisotropic periodic gratings at extreme angles." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16429/1/Steven_Goodman_Thesis.pdf.

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Bragg scattering of optical waves in thick gratings at extreme angles, where the scattered wave propagates parallel (extremely asymmetric scattering - EAS) or nearly parallel (grazing angle scattering - GAS) to the grating boundaries, is associated with many unique and practically important resonant phenomena. It has been demonstrated that one of the main physical mechanisms for these resonant phenomena is the diffractional divergence of the scattered wave inside and outside the grating region. This thesis fills the gaps in the theoretical and experimental understanding of Bragg scattering in gratings at extreme angles by investigating EAS and GAS in structures where diffractional divergence of waves is significantly affected by anisotropy and/or non-uniformities of the dielectric permittivity. Unusually high sensitivity of wave scattering in thick periodic gratings to small step-like variations of mean structural parameters at the grating boundaries is predicted and described for the case when the scattered wave (the +1 diffracted order) propagates almost parallel to the front grating boundary (the geometry of GAS). A unusual pattern of strong multiple resonances for bulk electromagnetic waves is predicted and analysed numerically in thick periodic holographic gratings in a guiding slab with mean permittivity that is greater than that of the surrounding media. It is demonstrated that these resonances are related to resonant generation of a new type of eigenmodes in a thick slab with a periodic grating. These eigenmodes are generically related to the grating -- they do exist not if the grating amplitude is zero. A new type of resonant coupling of bulk radiation into the conventional guided modes of a slab with a thick holographic grating is predicted and explained theoretically. It occurs in the presence of strong frequency detunings of the Bragg condition by means of interaction of the strongly non-eigen +1 diffracted order with the slab-grating boundaries. Therefore, it is only in the presence of step-like variations of the mean permittivity at the grating boundaries that this type of resonant coupling can occur. A new method for the analysis of EAS and GAS in anisotropic gratings is developed. This method is based on the consideration of the diffractional divergence of the scattered wave and the two-wave approximation in anisotropic gratings. Special efforts are focused on the analysis of EAS and GAS of extraordinary waves in uniaxial gratings. In particular, it is demonstrated that increasing curvature of the normal surface in the direction of propagation of the scattered wave results in increase of its diffraction divergence and the resonant amplitude. A theoretical model is developed for comparison of the theoretical predictions with data obtained from experimental observations of EAS in a holographic grating written in a photorefractive medium. The developed model is applied for the interpretation of experimental observations of EAS in BaTiO3 photorefractive crystals. Good agreement with the theoretical predictions is demonstrated.
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47

Goodman, Steven John. "Resonances of scattering in non-uniform and anisotropic periodic gratings at extreme angles." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16429/.

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Bragg scattering of optical waves in thick gratings at extreme angles, where the scattered wave propagates parallel (extremely asymmetric scattering - EAS) or nearly parallel (grazing angle scattering - GAS) to the grating boundaries, is associated with many unique and practically important resonant phenomena. It has been demonstrated that one of the main physical mechanisms for these resonant phenomena is the diffractional divergence of the scattered wave inside and outside the grating region. This thesis fills the gaps in the theoretical and experimental understanding of Bragg scattering in gratings at extreme angles by investigating EAS and GAS in structures where diffractional divergence of waves is significantly affected by anisotropy and/or non-uniformities of the dielectric permittivity. Unusually high sensitivity of wave scattering in thick periodic gratings to small step-like variations of mean structural parameters at the grating boundaries is predicted and described for the case when the scattered wave (the +1 diffracted order) propagates almost parallel to the front grating boundary (the geometry of GAS). A unusual pattern of strong multiple resonances for bulk electromagnetic waves is predicted and analysed numerically in thick periodic holographic gratings in a guiding slab with mean permittivity that is greater than that of the surrounding media. It is demonstrated that these resonances are related to resonant generation of a new type of eigenmodes in a thick slab with a periodic grating. These eigenmodes are generically related to the grating -- they do exist not if the grating amplitude is zero. A new type of resonant coupling of bulk radiation into the conventional guided modes of a slab with a thick holographic grating is predicted and explained theoretically. It occurs in the presence of strong frequency detunings of the Bragg condition by means of interaction of the strongly non-eigen +1 diffracted order with the slab-grating boundaries. Therefore, it is only in the presence of step-like variations of the mean permittivity at the grating boundaries that this type of resonant coupling can occur. A new method for the analysis of EAS and GAS in anisotropic gratings is developed. This method is based on the consideration of the diffractional divergence of the scattered wave and the two-wave approximation in anisotropic gratings. Special efforts are focused on the analysis of EAS and GAS of extraordinary waves in uniaxial gratings. In particular, it is demonstrated that increasing curvature of the normal surface in the direction of propagation of the scattered wave results in increase of its diffraction divergence and the resonant amplitude. A theoretical model is developed for comparison of the theoretical predictions with data obtained from experimental observations of EAS in a holographic grating written in a photorefractive medium. The developed model is applied for the interpretation of experimental observations of EAS in BaTiO3 photorefractive crystals. Good agreement with the theoretical predictions is demonstrated.
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48

Glytsis, Elias N. "Interdigitated electrodes and anisotropic diffraction analysis of phase and/or lossy gratings for bulk and integrated applications." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/14817.

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49

Mills, John David. "An investigation of phase-mask diffraction patterns and fibre Bragg gratings with scanning near-field optical microscopy." Thesis, University of Southampton, 2001. https://eprints.soton.ac.uk/15492/.

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In recent years, near-field microscopy has been utilized for assessing the properties of optical wave-guides at an increasing rate. Here, a Scanning Near-field Optical Microscope (SNOM) has been designed and constructed in order to expand this work into an analysis of the optical and structural properties of fibre Bragg gratings, which are used throughout the optical fibre telecommunications network. By imaging the evanescent fields of Bragg gratings, a characterization technique has been developed which has enabled the acquisition of sub-wavelength information about the optical field distribution within a fibre grating and its refractive index structure. Six separate fibre grating samples have been examined, demonstrating the feasibility of the developed scanning technique to become a useful characterization tool. In particular, the study has enabled grating standing wave fringes to be imaged relative to corresponding refractive index fringes, for the first time. The SNOM has also been utilized to map free-space diffraction patterns close to a phase-mask (transmission diffraction grating). The patterns are normally used to create fibre gratings via UV photosensitivity mechanisms. The field distributions have been imaged under various experimental conditions and have revealed some of the technical problems that might occur during the writing of gratings. The measured patterns have also served to confirm existing diffraction grating theory, which has been expanded during the course of this work to produce a new expression for the 'Talbot length', originally formulated by Rayleigh in 1881.
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50

Constant, Thomas J. "Optical excitation of surface plasmon polaritons on novel bigratings." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/9001.

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This thesis details original experimental investigations in to the interaction of light with the mobile electrons at the surface of metallic diffraction gratings. The gratings used in this work to support the resultant trapped surface waves (surface plasmon polaritons), may be divided into two classes: ‘crossed’ bigratings and ‘zigzag’ gratings. Crossed bigratings are composed of two diffraction gratings formed of periodic grooves in a metal surface, which are crossed at an angle relative to one another. While crossed bigratings have been studied previously, this work focuses on symmetries which have received comparatively little attention in the literature. The gratings explored in this work possesses two different underlying Bravais lattices: rectangular and oblique. Control over the surface plasmon polariton (SPP) dispersion on a rectangular bigrating is demonstrated by the deepening of one of the two constituent gratings. The resulting change in the diffraction efficiency of the surface waves leads to large SPP band-gaps in one direction across the grating, leaving the SPP propagation in the orthogonal direction largely unperturbed. This provides a mechanism to design surfaces that support highly anisotropic propagation of SPPs. SPPs on the oblique grating are found to mediate polarisation conversion of the incident light field. Additionally, the SPP band-gaps that form on such a surface are shown to not necessarily occur at the Brillouin Zone boundaries of this lattice, as the BZ boundary for an oblique lattice is not a continuous contour of high-symmetry points. The second class of diffraction grating investigated in this thesis is the new zigzag grating geometry. This grating is formed of sub-wavelength (non-diffracting) grooves that are ‘zigzagged’ along their length to provide a diffractive periodicity for visible frequency radiation. The excitation and propagation of SPPs on such gratings is investigated and found to be highly polarisation selective. The first type of zigzag grating investigated possesses a single mirror plane. SPP excitation to found to be dependant on which diffracted order of SPP is under polarised illumination. The formation of SPP band-gaps is also investigated, finding that the band-gap at the first Brillouin Zone boundary is forbidden by the grating’s symmetry. The final grating considered is a zigzag grating which possesses no mirror symmetry. Using this grating, it is demonstrated that any polarisation of incident light may resonantly drive the same SPP modes. SPP propagation on this grating is found to be forbidden in all directions for a range of frequencies, forming a full SPP band-gap.
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