Academic literature on the topic 'Graded photonic crystal'
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Journal articles on the topic "Graded photonic crystal":
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Qi, YongLe, XiaoHong Sun, Shuai Wang, WenYang Li, and ZhongYong Wang. "Design of an Electrically Tunable Micro-Lens Based on Graded Photonic Crystal." Crystals 8, no. 7 (July 23, 2018): 303. http://dx.doi.org/10.3390/cryst8070303.
Abstract:
A micro-lens with an adjustable focal length (FL) is designed by using Graded Photonic Crystal (GPC) structures and a Polymer Dispersed Liquid Crystal (PDLC) material. The GPCs are formed by gradually changing the radius of the polymer rods in the Photonic Crystal (PC) with square lattices of polymer rods in the background of Liquid Crystals (LCs). The electrically tunable focusing characteristics of the micro-lens are investigated by loading a continuous voltage source to change the LC rotation angle. The sensitivity of the focal shift in terms of LCs tilting angle is 0.152 λ(nm/deg). Moreover, the effect of the defects and deviations on the focusing characteristics are also analyzed. This research is crucial for future applications of the proposed device in the integrated photonics and adaptive optics.
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Hassan, Safaa, Oliver Sale, David Lowell, Noah Hurley, and Yuankun Lin. "Holographic Fabrication and Optical Property of Graded Photonic Super-Crystals with a Rectangular Unit Super-Cell." Photonics 5, no. 4 (October 11, 2018): 34. http://dx.doi.org/10.3390/photonics5040034.
Abstract:
Recently developed graded photonic super-crystals show an enhanced light absorption and light extraction efficiency if they are integrated with a solar cell and an organic light emitting device, respectively. In this paper, we present the holographic fabrication of a graded photonic super-crystal with a rectangular unit super-cell. The spatial light modulator-based pixel-by-pixel phase engineering of the incident laser beam provides a high resolution phase pattern for interference lithography. This also provides a flexible design for the graded photonic super-crystals with a different ratio of length over the width of the rectangular unit super-cell. The light extraction efficiency is simulated for the organic light emitting device, where the cathode is patterned with the graded photonic super-crystal. The high extraction efficiency is maintained for different exposure thresholds during the interference lithography. The desired polarization effects are observed for certain exposure thresholds. The extraction efficiency reaches as high as 75% in the glass substrate.
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Sano, Daisuke, and Soshu Kirihara. "Fabrication of Metal Photonic Crystals with Graded Lattice Spacing by Using Micro-Stereolithography." Materials Science Forum 631-632 (October 2009): 287–92. http://dx.doi.org/10.4028/www.scientific.net/msf.631-632.287.
Abstract:
We designed micro-scale photonic crystal with or without graded lattice spacing composed of copper to control Terahertz (THz) waves. Designed structures were fabricated by using micro-stereolithography. By proper dewaxing and sintering process, pure copper photonic crystals were obtained. Transmission properties of THz waves propagating through the photonic crystals were measured by THz time-domain spectroscopy. Measured results showed good agreements with the simulated results.
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Liu, Wei, Hechao Liu, Xiaohong Sun, and Fan Zhang. "The Design of Large Curved Waveguide Based on Sunflower Graded Photonic Crystal." Photonics 10, no. 7 (July 5, 2023): 781. http://dx.doi.org/10.3390/photonics10070781.
Abstract:
In this paper, three large curved waveguides based on Sunflower Graded photonic crystal are designed. Numerical simulations of electromagnetic beam bending in Sunflower Graded photonic crystals have shown that homogenization based on the Maxwell–Garnett theory gives very good results for steering the electromagnetic field. In contrast to the progressive bending waveguide structures based on periodic photonic crystal designs reported in the literature, this structure is not only simple in design, but also the optical wave trends in the progressive bending waveguide structures are more smooth. Sunflower structures, due to their high circular symmetry, have a great advantage in making arbitrary curved waveguides. The results have some theoretical implications for the design of optical integrated circuits and the selection of optically thin communication devices. It is also useful for the selection of meta-materials.
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Rezaei, Behrooz, Ibrahim Halil Giden, Mohammad Sadegh Zakerhamidi, Amid Ranjkesh, and Tae-Hoon Yoon. "Two-Dimensional Hybrid Photonic Crystal With Graded Low-Index Using a Nonuniform Voltage." Zeitschrift für Naturforschung A 75, no. 1 (December 18, 2019): 65–71. http://dx.doi.org/10.1515/zna-2019-0144.
Abstract:
AbstractWe proposed a new method for designing graded index lens using liquid crystal infiltration into annular photonic crystals. Applying an external nonuniform voltage in the transverse direction perpendicular to the direction of light propagation yields different orientation of liquid crystal molecules inside the photonic crystal unit cells. As a result, a gradient refractive index was modulated. We numerically investigate focusing properties of the designed graded index structure using plane-wave expansion and finite-difference time-domain methods. The gradient refractive index profile was adjusted by varying the nonuniform voltage excitations, which consequently altered the focal distance of the graded index structure. A wide tuning range of 1856 nm was achieved for focal distance by the proposed graded index structure. This feature can be implemented for planning a flat lens with tunable focal distance based on electro-optic effect. These achievements may have future applications in some optical devices such as near-field imaging and scanning.
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Chassagneux, Y., R. Colombelli, W. Maineult, S. Barbieri, S. P. Khanna, E. H. Linfield, and A. G. Davies. "Graded photonic crystal terahertz quantum cascade lasers." Applied Physics Letters 96, no. 3 (January 18, 2010): 031104. http://dx.doi.org/10.1063/1.3273056.
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Chen Sujuan, 陈素娟, 周崇喜 Zhou Chongxi, 邱传凯 Qiu Chuankai, and 罗先刚 Luo Xiangang. "Focusing Lens by Three-Dimensional Graded Photonic Crystal." Acta Optica Sinica 30, no. 8 (2010): 2427–31. http://dx.doi.org/10.3788/aos20103008.2427.
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Park, J. H., W. S. Choi, H. Y. Koo, and D. Y. Kim. "Colloidal Photonic Crystal with Graded Refractive-Index Distribution." Advanced Materials 17, no. 7 (April 4, 2005): 879–85. http://dx.doi.org/10.1002/adma.200400632.
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Giden, Ibrahim Halil, Neslihan Eti, Behrooz Rezaei, and Hamza Kurt. "Adaptive Graded Index Photonic Crystal Lens Design via Nematic Liquid Crystals." IEEE Journal of Quantum Electronics 52, no. 10 (October 2016): 1–7. http://dx.doi.org/10.1109/jqe.2016.2605398.
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Rezaei, B., I. H. Giden, and H. Kurt. "Tuning light focusing with liquid crystal infiltrated graded index photonic crystals." Optics Communications 382 (January 2017): 28–35. http://dx.doi.org/10.1016/j.optcom.2016.07.062.
Dissertations / Theses on the topic "Graded photonic crystal":
1
Zheng, Xin. "Graded photonic crystal for silicon photonics." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPAST063.
Abstract:
Les cristaux photoniques à gradient (CPG) permettent une ingénierie de leur indice effectif, ce qui offre de nouveaux degrés de liberté pour la conception de dispositifs photoniques. Ils s’appréhendent par l’optique à gradient d’indice (GRIN optics), qui décrit des milieux inhomogènes dans lesquels la lumière ne se propage pas rectilignement. Il est ainsi possible d’envisager tout profil d’indice. Les CPG sont donc particulièrement attractifs pour la miniaturisation des composants optiques, notamment en photonique sur Silicium. Ils sont fondés sur la variation d’un paramètre de la maille élémentaire du cristal photonique (CP); ici, c’est le facteur de remplissage qui varie afin que l’indice effectif du CPG réalise le profil d’indice souhaité. Le but de cette thèse est d’explorer le potentiel des CPG en concevant des dispositifs à gradient d’indice sur la "plateforme" Silicium sur isolant (SOI) aux longueurs d’onde pour les télécommunications. C’est la chaine complète qui va de la conception à la caractérisation du dispositif, en passant par la simulation et la fabrication, qui est mise en œuvre. Nous nous sommes principalement concentrés sur deux instruments typiques de l’optique à gradient d’indice : la lentille de Mikaelian et le Half Maxwell Fish Eye (HMFE). Dans cette thèse, nous proposons une nouvelle méthode d’approximation de l’indice effectif adaptée à la "plateforme" SOI, que nous avons validée en concevant une lentille de Mikaelian (à profil d’indice sécante hyperbolique). Pour de tels dispositifs, il faut en effet tenir compte de deux indices effectifs : celui du mode guidé dans la couche de Silicium et celui du CP. Dans cette méthode, l’indice effectif du CP est d’abord calculé pour remplacer l’indice de la couche du mode guidé ; puis l’indice effectif de cette couche est calculé. Les résultats de simulation obtenus au moyen d’un logiciel commercial (méthode FDTD) montrent que la lentille ainsi conçue satisfait les prévisions analytiques, contrairement à ce que donnent les méthodes couramment utilisées. Nous l’avons alors appliquée au HMFE. Les dispositifs ont ensuite été fabriqués en salle blanche par lithographie par faisceau d’électrons (EBL) et par gravure plasma (ICP). Les différents CPG fabriqués consistent en des trous d’air répartis périodiquement dans la couche de Silicium, dont le diamètre minimal est d’environ 40 nm. Puis, ils ont été caractérisés en deux temps, notamment par microscopie en champ proche (SNOM). L’épaisseur de ces dispositifs est de quelques longueurs d’onde (3 ou 5 λ_0 environ), tandis la largeur de leur tâche focale est proche de la limite de diffraction (0.5 λ_0 environ). Ils fonctionnent sur une plage de longueurs d’onde de 150 nm environ. Les résultats de la lentille de Mikaelian ont été utilisés pour développer un convertisseur de taille de mode (taper) effectif sur quelques longueurs d’onde. Il est dix fois plus court qu’un convertisseur classique. Dans cette thèse, nous montrons aussi comment il est possible d’interpréter la propagation de l’onde EM dans ces composants à gradient d’indice sur "plateforme" SOI au moyen du principe de l’interféromètre multimode. En se propageant, les différents modes accumulent une différence de phase, qui se traduit par un battement qui modifie la distribution du champ EM, conduisant à la focalisation. La longueur caractéristique de ce battement est égale à la distance focale. Tous ces dispositifs sont étudiés pour s’intégrer dans des circuits de photonique intégréeGradient photonic crystals (GPhCs) enable the engineering of their effective index, opening up new degrees of freedom in photonic device design. They can be understood through gradient index optics (GRIN optics), which describe inhomogeneous media in which light does not propagate along straight paths. This makes it possible to consider any index profile. This makes GPhCs particularly attractive for the miniaturization of optical components, especially in silicon photonics. They are based on the variation of a parameter of the photonic crystal elemental cell (PhC); here, the filling factor is varied so that the effective index of the GPhC achieves the desired index profile. The aim of this thesis is to explore the potential of GPhCs by designing graded-index devices on the Silicon-On-Insulator (SOI) "platform" at telecom wavelengths. The complete chain from design to device characterization, including simulation and manufacturing, is implemented. We focused on two typical gradient index optics instruments: the Mikaelian lens and the Half Maxwell Fish Eye (HMFE). In this thesis, we propose a new effective index approximation method for the SOI "platform", which we have validated by designing a Mikaelian lens (with a hyperbolic secant index profile). For such devices, two effective indices need to be taken into account: that of the guided mode in the Silicon layer and that of the PhC. In this method, the effective index of the PhC is first calculated to replace the index of the guided mode layer; then the effective index of this layer is calculated. Simulation results obtained using commercial software (FDTD method) show that the lens designed in this way satisfies the analytical predictions, contrary to the results obtained with commonly used methods. We then applied it to HMFE.The devices were then fabricated in the cleanroom by electron beam lithography (EBL) and plasma etching (ICP). The individual GPhCs consisted of periodically distributed air holes in the Silicon layer, with a minimum diameter of around 40 nm. They were then characterized in two stages, notably by near-field microscopy (SNOM). These devices are only a few wavelengths thick (approx. 3 or 5 λ_0), while their focal spot width is close to the diffraction limit (approx. 0.5 λ_0). They operate over a wavelength range of around 150 nm. The Mikaelian lens results have been used to develop a mode size converter (taper), which is effective over a few wavelengths. It is ten times shorter than a conventional converter. In this thesis, we also show how it is possible to interpret EM wave propagation in these graded-index components on the SOI platforms using the multimode interferometer principle. As they propagate, the different modes accumulate a phase difference, resulting in a mode beat that modifies the EM field distribution, leading to focusing. The characteristic length of this mode beat is equal to the focal length. All these devices are studied for integration into integrated photonics circuits
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Hassan, Safaa. "Optical Property Study of 2D Graded Photonic Super-Crystals for Photon Management." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1703318/.
Abstract:
In this dissertation, we study the optical property of 2D graded photonic super-crystals (GPSCs) for photon management. We focused primarily on manipulation and control of light by using the newly discovered GPSCs which present great opportunity for electromagnetic wave control in photonic devices. The GPSC has been used to explore the superior capability of improving the light extraction efficiency of OLEDs. The enhancement of extraction efficiency has been explained in term of destructive interference of surface plasmon resonance and out-coupling of surface plasmon through phase matching provided by GPSC and verified by e-field intensity distributions. A large light extraction efficiency up to 75% into glass substrate has been predicted through simulation. We also study the light trapping enhancement in GPSCs. Broadband, wide incident angle, and polarization independent light trapping enhancement is achieved in silicon solar cells patterned with the GPSCs. In addition, novel 2D GPSCs were fabricated using holographic lithography through the interference lithography by two sets of multiple beams arranged in a cone geometry using a spatial light modulator (SLM). Finally, we also report a fabrication of GPSCs with a super-cell size of 12a×12a by using e-beam lithography. Diffraction pattern from GPSCs reveals unique diffraction properties. In an application aspect, light emitting diode arrays can be replaced by a single light emitting diode shinning onto the diffraction pattern for a uniform fluorescence.
3
Lowell, David. "Fabrication and Study of the Optical Properties of 3D Photonic Crystals and 2D Graded Photonic Super-Crystals." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1404552/.
Abstract:
In this dissertation, I am presenting my research on the fabrication and simulation of the optical properties of 3D photonic crystals and 2D graded photonic super-crystals. The 3D photonic crystals were fabricated using holographic lithography with a single, custom-built reflective optical element (ROE) and single exposure from a visible light laser. Fully 3D photonic crystals with 4-fold, 5- fold, and 6-fold symmetries were fabricated using the flexible, 3D printed ROE. In addition, novel 2D graded photonic super-crystals were fabricated using a spatial light modulator (SLM) in a 4f setup for pixel-by-pixel phase engineering. The SLM was used to control the phase and intensity of sets of beams to fabricate the 2D photonic crystals in a single exposure. The 2D photonic crystals integrate super-cell periodicities with 4-fold, 5-fold, and 6-fold symmetries and a graded fill fraction. The simulations of the 2D graded photonic super-crystals show extraordinary properties such as full photonic band gaps and cavity modes with Q-factors of ~106. This research could help in the development of organic light emitting diodes, high-efficiency solar cells, and other devices.
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Zhao, Mingrui, and Manish Keswani. "Fabrication of Radially Symmetric Graded Porous Silicon using a Novel Cell Design." NATURE PUBLISHING GROUP, 2016. http://hdl.handle.net/10150/614761.
Abstract:
A contactless method using a novel design of the experimental cell for formation of porous silicon with morphological gradient is reported. Fabricated porous silicon layers show a large distribution in porosity, pore size and depth along the radius of the samples. Symmetrical arrangements of morphology gradient were successfully formulated radially on porous films and the formation was attributed to decreasing current density radially inward on the silicon surface exposed to Triton (R) X-100 containing HF based etchant solution. Increasing the surfactant concentration increases the pore depth gradient but has a reverse effect on the pore size distribution. Interestingly, when dimethyl sulfoxide was used instead of Triton (R) X-100 in the etchant solution, no such morphological gradients were observed and a homogeneous porous film was formed.
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Do, Khanh Van. "Contribution à l’exploration des propriétés dispersives et de polarisation de structures à cristaux photoniques graduels." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112237/document.
Abstract:
Cette thèse apporte une contribution théorique et expérimentale à l'exploration des propriétés de dispersion et de polarisation de structures à cristaux photoniques à gradient (GPhCs). Nous explorons pour commencer la relation qui existe entre les déformations des surfaces équi-fréquences (EFS) de différents cristaux photoniques et les paramètres de maille des configurations envisagées. Compte tenu de la complexité des structures possibles obtenues à partir d'un chirp spatial bidimensionnel d'au moins un paramètre de maille, nous avons limité notre étude à un type particulier de structure basé sur un réseau carré de silicium sur isolant (SOI) planaire constitué de trous d'air de facteur de remplissage variable. Une expression analytique des EFS connexes en fonction du rayon des motifs a d’abord été extraite, et une structure GPhC de "référence" a ensuite été proposé pour l'exploration des propriétés de dispersion et de polarisation des GPhCs utilisant à la fois une approche consistant à propager un ou plusieurs rayons optiques dont les trajectoires sont données par les équations de l’optique Hamiltonienne et une approche tout numérique basée sur des simulations FDTD. Nous décrivons ensuite les processus de fabrication de salle blanche des structures à cristaux photoniques graduels, obtenues à partir de substrats semiconducteurs par lithographie par faisceau d'électrons et gravure ionique réactive. Les échantillons fabriqués sont étudiés expérimentalement par des techniques de mesure en champ lointain et en champ proche (SNOM) en s'appuyant sur une collaboration avec un autre groupe du CNRS. Les résultats expérimentaux montrent une relation dispersive quasi-linéaire de 0.25μm/nm dans la gamme de longueur d’onde allant de 1470nm à 1600nm. Les premiers dispositifs fabriqués présentent aussi la possibilité de séparer des couples de deux longueurs d'onde (démultiplexage) avec des pertes d'insertion faibles (inférieures à 2 dB) et un niveau de diaphonie faible (de l'ordre de -20 dB). Ils présentent également un effet très net de séparation des polarisations de la lumière avec une diaphonie inter-polarisations TE/TM de -27dB dans une bande spectrale de l’ordre de 70 nm. Au-delà de ces mesures optiques obtenus dans une configuration particulière de cristal photonique graduel, les travaux présentés dans cette thèse ont permis l'observation directe de la transition entre les régimes d’homogénéisation et de diffraction de propagation de la lumière dans un matériau optique artificiel tout diélectrique. Globalement, la méthodologie présentée et adoptée pour l'étude de la propagation de la lumière dans les structures étudiées a ouvert des perspectives pour la réalisation de fonctions optiques plus complexesThis PhD thesis brings a theoretical and experimental contribution to the exploration of dispersive and polarization properties of graded photonic crystal (GPhC) structures. We first present a quantitative relationship between the deformations of the equi-frequency surfaces (EFSs) of different photonic crystals and the lattice parameters of the considered configurations. Considering the complexity of the possible GPhC structures made of a two-dimensional spatial chirp of at least one lattice parameter, we limit in this thesis our study to one particular type of GPhC structure based on a square lattice silicon on insulator (SOI) planar photonic crystal with a variable air hole filling factor profile. An analytical expression of the related EFSs as a function of the varied lattice parameter is extracted, and a GPhC “reference” structure is then proposed for the exploration of the dispersive and polarization properties of GPhCs using both Hamiltonian optic-assisted ray tracing as well as FDTD simulations. The clean room fabrication process of this GPhC structure family, which is based on electron beam lithography and reactive ion etching technologies, is reported. Fabricated samples are experimentally studied by far-field and near-field (SNOM) measurement techniques relying on a collaboration with a CNRS group of the Bourgogne university. Experimental results show an almost linear dispersive relationship of 0.25µm/nm in the 1470nm-1600nm spectral range. The fabricated samples also present the possibility for two-wavelength demultiplexing with low insertion loss (below 2dB) and low crosstalk level (around -20dB), and a polarization beam splitting effect with a crosstalk of -27dB in a 70nm bandwidth. Beyond these optical metrics obtained in one particular GPhC configuration, the works presented in this thesis have allowed the direct observation of the transition between the homogeneous and diffraction regimes of light propagation in an artificial optical all-dielectric material, and the presented and adopted methodology for the study of light propagation in GPhC structures has raised open perspectives for the realization of more complex optical functions in forthcoming works using low loss and flexible metamaterial-like photonic crystals
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Gaufillet, Fabian. "Cristaux photoniques à gradient : dispositifs et applications." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112295.
Abstract:
Les matériaux artificiellement structurés que sont les cristaux photoniques sont couramment utilisés pour leurs propriétés dispersives. Leur constante diélectrique varie périodiquement à l'échelle de la longueur d'onde selon deux ou trois directions avec un contraste d'indice suffisamment élevé. La relation de dispersion ω = ω(k) qui résulte de cette variation périodique a la forme d'une structure de bande à l'intérieur de laquelle il existe des bandes interdites photoniques où la propagation du champ électromagnétique est interdite. En dehors de ces bandes, i.e. dans les bandes photoniques, se trouvent les propriétés de dispersion des cristaux photoniques.Le but de ce travail de thèse est de concevoir, de fabriquer et de caractériser des dispositifs à cristal photonique à gradient. Ces dispositifs ont été conçus de façon à s'appliquer dans les domaines allant des micro-ondes à l'optique. Nous avons conçu des dispositifs à partir de cristaux photoniques dont les propriétés dispersives les rendent analogues à des milieux linéaires, homogènes et isotropes (LHI). À la maille élémentaire de ces cristaux photoniques LHI, nous avons appliqué un gradient pour réaliser des lentilles à gradient 1D. Des résultats importants concernant la conception, la fabrication et la caractérisation expérimentale d'une lentille plate à gradient d'indice fonctionnant dans la bande X des micro-ondes sont reportés. Celle lentille focalise une onde plane incidente et collimate l'onde émise par une source ponctuelle situés dans son plan focal. Si cette lentille constitue en soi un démonstrateur et valide la démarche mise en œuvre pour la concevoir, ses applications potentielles concernent particulièrement les antennes. Nous réalisons également plusieurs lentilles à gradient 2D dont des lentilles de Lüneburg et Half Maxwell Fisheye; leurs applications aux antennes sont importantes. Nous nous intéressons aussi à la réalisation de lentilles optiques à gradient d'indice dites « SELFOC® ». Dans le but de confirmer les propriétés dispersives remarquables qui ont été mises en évidence, nous avons poursuivi dans ce sens en revisitant une expérience classique qui met en évidence l'existence des ondes évanescentes : celle du « double prisme à angle droit ». Nous mettons également en évidence le phénomène de « réflexion totale frustrée » ainsi que le décalage, découvert par Goos et Hänchen, que subit l'onde réfléchie sur le dioptre. Ce sont ces deux points — réflexion totale frustrée et effet Goos-Hänchen — que nous vérifions dans le cas de cristaux photoniques LHIArtificially structured materials that are photonic crystals are commonly used for their dispersive properties. Their dielectric constant varies periodically across the wavelength in two or three directions with a sufficiently high index contrast. The resulting dispersion relation ω = ω(k) of the periodic variation has the form of a band structure within which there are photonic bandgaps in which the propagation of the electromagnetic field is prohibited. Outside of these bands, i.e. in the photonic band, there are the dispersion properties of the photonic crystals.The aim of this thesis is to design, fabricate and characterize graded photonic crystal devices. These devices were designed to be applied in areas ranging from microwaves to optics. We designed devices from photonic crystals with dispersive properties which make them similar to linear, homogeneous and isotropic media (LHI). In the unit cell of the LHI photonic crystal, we applied a gradient to achieve 1D graded lenses. Important results regarding the design, manufacturing and experimental characterization of a flat lens GRIN operating in X-band microwaves are deferred. This lens focuses an incident plane wave and collimates the wave emitted by a point source located in its focal plane. If this lens is itself a demonstrator and validates the approach implemented for the design, its potential applications particularly concern antennas. We also carry several 2D graded lenses including Lüneburg and Half Maxwell Fisheye lenses; their applications to the antennas are important. We are also interested in making optical graded index lenses called "SELFOC®".In order to confirm the remarkable dispersive properties that have been identified, we continued in that direction by revisiting a classic experiment that highlights the existence of evanescent waves: the "double right angle prism". We also highlight the phenomenon of "frustrated total internal reflection" and the shift discovered by Goos and Hänchen suffered by the reflected wave on the interface. It's these two points – frustrated total internal reflection and Goos-Hänchen effect - that we check in the case of LHI photonic crystals
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Cheng, Yu-Chieh, and 鄭鈺潔. "Study of Graded Photonic Crystal Cavities." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/13088426478779350949.
Abstract:
碩士國立中央大學
光電科學研究所
99
In this study, the photonic crystals nanocavity has been designed, fabricated, and characterized in GaN bulk materials with the heterostructure which could achieve extremely high-Q factors. The device characterization was performed at room temperature using a micro-photoluminescence system. We obtain a lasing signal whose full width at half maximum (FWHM) obtained by Gaussian curve fitting is ??=0.04 nm for ?=362 nm and the threshold of excitation power is found to be 0.9 mW, corresponding to the power density of 17 kmW/cm2. The Q-factor of the cavity is as high as 104.
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Chien, Hung-Ta, and 簡宏達. "Study of Graded Photonic Crystal Lens." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/23g2j7.
Abstract:
博士國立中央大學
光電科學研究所
97
In this work, we studied the graded photonic crystal consisting of spatial-varying air holes in a square array theoretically and experimentally. The radii of the air holes are identical in each column and modified from the central column to the edge column. We found that the graded photonic crystal could focus the electromagnetic waves. Through finite-difference time-domain method, we studied the relations between the geometry of the graded photonic crystal, focal length, spot size, and the intensity at focal point. The structure focuses the electromagnetic waves to a focal point measuring only two lattice constants which is close to the width of a single-line-defect photonic crystal waveguide. Therefore, the graded photonic crystal is applied to the issue of the coupling between photonic crystal waveguides and conventional dielectric waveguides. The coupling efficiency is compared with various couplers including the photonic crystal taper, the waveguide taper, and the parabolic mirror coupler. All of the couplers were designed and fabricated on a silicon-on-insulator substrate. The simulation and experimental results suggest that the graded photonic crystal coupler could offer a higher coupling efficiency in a shorter coupling length. Besides, the innate properties of each coupler are discussed.
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Hsing-HungChiang and 江興鴻. "Focusing Analysis of Sectorial Graded Photonic Crystal." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/45756242511283762826.
Abstract:
碩士國立成功大學
製造資訊與系統研究所碩博士班
101
The photonic crystal is a periodic artificial structure. This structure produces photonic bandgaps, make the light of certain frequency bands can not pass in it. So we can use the characteristic of photonic crystal structure to have application and design some optical components. Because of Yablonovitch and John found the characteristic of photonic crystal structure few decades ago, many researchers began to be interested in the photonic crystal and studied extensively in this direction as possible as they can. Because the photonic band gap can be designed purposely, the vast majority of research in this field has been devoted to applications of the bandgap and defects in photonic crystal. Recently, the research has been extended to new transmission phenomena such as the superprism, self-collimation, negative refraction and slab lens. In this paper, we research a two-dimensional sectorial graded photonic crystal base on a graded photonic crystal lens with square lattice of air columns. The radii of the air columns are identical in horizontal arrangement and are modified from the central to the edge in vertical arrangement. We change the geometric shape, radius of curvature and periodic arrangement to optimize the structure, and discuss the parameters of the focal length, the depth of focus, the size of focal point and the focusing intensity. Then we apply the sectorial graded photonic crystal to the photonic crystal waveguide coupling, and compare the coupling efficiency of it with other couplers including the graded photonic crystal lens waveguide and the curved graded photonic crystal waveguide. We calculate and analyze the properties of the photonic crystal we design by using plane wave expansion method and finite-difference time-domain method here. All of the couplers are designed and fabricated on a silicon-on-insulator substrate. The simulation and experimental results suggest that the sectorial graded photonic crystal coupler could offer a higher coupling efficiency in a short coupling length. Besides, the innate properties of each coupler are discussed. The graded photonic crystal lens has the short focal length and coupling length, but its disadvantage is that the coupling efficiency is low. The curved graded photonic crystal has the longest depth of focus than the others, but its disadvantages are that the focal length and coupling length are long resulting in demand for space during the manufacturing process. Therefore, the sectorial graded photonic crystal is the most suitable for application in the coupler than the graded photonic crystal lens and the curved graded photonic crystal. Its coupling efficiency is 56.2% almost double of the graded photonic crystal lens’s coupling efficiency 28.4%.
10
Lu, Tsung-Yi, and 呂宗益. "Study of acousto-optic coupling in graded photonic crystal nanobeam cavities." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/vaj2pb.
Abstract:
碩士國立臺灣海洋大學
光電科學研究所
102
Acousto-optic coupling in graded photonic crystal nanobeam cavities is theoretically investigate with the finite-element method. We propose a hybrid optical nanocavity consisting of photonic crystals with a metal-plate. The hybridization of photonic crystal modes and surface plasmonic modes forms hybrid cavity modes, which are highly confined around the interface between GaAs crystals and an Ag metal-plate. The nanocavity has high quality factor and low mode volume. We show that high-Q/Vm leads to enhanced acousto-optic coupling in a nanocavity. Numerical results indicate that the breathing mode of acoustic wave causes the optical resonant wavelength shift of 6 nm in the nanocavity. The novel graded photonic crystal nanobeam cavities open up opportunities for various applications in enhanced acousto-optic coupling.
Book chapters on the topic "Graded photonic crystal":
1
Singh, Bipin Kumar, and Praveen Chandra Pandey. "Effect of Exponentially Graded Material on Photonic and Omni-Directional Band Gaps in 1-D Photonic Crystals." In Springer Proceedings in Physics, 119–44. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-30137-2_8.
2
Kirihara, Soshu, and Yoshinari Miyamoto. "Selective Transmission of Electromagnetic Wave by Using Diamond Photonic Crystals with Graded Lattice Spacing." In Advances in Science and Technology, 1139–44. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/3-908158-01-x.1139.
3
"Photonic Crystals and Metamaterials." In Physics and Engineering of Graded-Index Media, 292–314. Cambridge University Press, 2023. http://dx.doi.org/10.1017/9781009282086.011.
4
Chouhan, Er R. K., and Manish Mudgal. "Novel Radiation Shielding Concrete Utilizing Industrial Waste for Gamma-Ray Shielding." In Smart Materials Design for Electromagnetic Interference Shielding Applications, 527–54. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815036428122010015.
Abstract:
For the first time, the capability of red mud waste has been explored for the development of advanced synthetic radiation shielding aggregate and radiation shielding concrete. Red mud, an aluminium industry waste, consists of multi.component and multi-elemental characteristics. Approximately two tons of red mud are generated for every ton of aluminium production. There are about 85 alumina plants all over the world, thus leading to the generation of about 77 million tons of highly alkaline waste annually. The major mineral content of red mud waste includes hematite, anatase, and cancrinite, thus making red mud waste the most suitable multi.component resource material for developing multi phases containing shielding aggregate. Further, these multi-elements in the red mud are present in the form of oxide, oxy-hydroxide, and hydroxides, having low as well as high atomic number elements, namely sodium, iron, titanium compounds, respectively, and are non-toxic in nature. The concrete possessing specific gravity higher than 2600 kg/m3 is known as heavyweight concrete, and aggregate with specific gravities higher than 3000 kg/m3 is called heavyweight aggregate as per TS EN 206-1 (2002). The shielding aggregate contains both naturally occurring as well as some of the artificial aggregate. The natural aggregate includes hematite, magnetite, limonite barite, etc., which are non.replenishable and are useful for many other important applications, and the artificial aggregate includes the use of iron shots and steel filing and in some cases, lead shots, etc. The use of lead shots makes the material toxic in nature, therefore, there is a need to avoid the use of lead-based materials for shielding applications, as it ranks second in the list of hazardous materials. Apart from toxicity associated with lead, the low melting point of lead is also prohibitive as the shielding concrete should be preferably heat and fire-resistant. Further, all the natural minerals inherently contain only a single shielding phase, therefore, conventionally shielding concretes are developed by a combination of various natural minerals, which leads to an inhomogeneous radiation shielding matrix in the developed conventional radiation shielding concrete. In view of the above, there is an urgent need to develop advanced non-toxic synthetic shielding aggregate capable of providing homogeneous radiation shielding matrix preferably obviating the use of toxic lead and conventional non-replenishable natural minerals resources. In this chapter, aluminium industrial waste, i.e., red mud, has been utilized. Chemical formulation and mineralogical designing of the red mud has been done by ceramic processing using appropriate reducing agents and additives. The chemical analysis, SEM microphotographs, and XRD analysis confirm the presence of multi-component, multi shielding, and multi-layered phases in developed advanced synthetic radiation shielding aggregate. The maximum density of developed synthetic aggregate is found to be 4.16 g/cc. The mechanical properties, namely aggregate impact value, aggregate crushing value, and aggregate abrasion value, have been evaluated and was compared with hematite ore aggregate and found to be an excellent material useful for making advanced radiation shielding concrete for the construction of nuclear power plants and other radiation installations. For the first time, the development and design mix of novel radiation shielding concrete using innovative red mud-based synthetic shielding aggregates have been carried out in which the heavy density shielding aggregates are developed using red mud and are basically ceramic materials consisting of shielding phases, namely barium silicate (san-bornite), barium iron titanium silicate (bafertisite), barium aluminium silicate, iron titanium oxide (pseudorutile), barium titanate, barium iron titanium oxide, barium aluminium oxide, and magnetite, which are multi-elemental, multi phases, multi-layered crystal structures, therefore, they are excellent shielding materials. The radiation shielding concrete was made using developed synthetic shielding aggregates adopting IS 10262-2009 standard for grade designation of M-30 concrete. The reference hematite ore concrete and developed concrete tested for radiation shielding attenuation properties for gamma rays using 137Cs (of photon energy 662 keV) and 241Am (of photon energy 60 keV) were found to possess highly effective shielding properties. The developed novel design mix concrete achieved an attenuation factor of 5.8 as compared to 5.1 attenuation factor for reference hematite ore concrete. The developed radiation shielding concrete using red mud-based synthetic shielding aggregates possess a broad application spectrum ranging from the construction of diagnostic X-ray, CT scanner rooms, and storing radioactive waste to nuclear power plants.
Conference papers on the topic "Graded photonic crystal":
1
Chien, Hung-Ta, and Chii-Chang Chen. "Waveguide coupler formed by a Graded Photonic Crystal." In National Fiber Optic Engineers Conference. Washington, D.C.: OSA, 2009. http://dx.doi.org/10.1364/nfoec.2009.jtha20.
2
Qi, YongLe, XiaoHong Sun, and Shuai Wang. "Fabrication of double-periodic graded photonic crystal array." In Holography, Diffractive Optics, and Applications VIII, edited by Chongxiu Yu, Changhe Zhou, and Yunlong Sheng. SPIE, 2018. http://dx.doi.org/10.1117/12.2502420.
3
Turduev, Mirbek, Ibrahim I. Taskiran, and Hamza Kurt. "Penrose type graded photonic quasi-crystal for light manipulation." In 2015 17th International Conference on Transparent Optical Networks (ICTON). IEEE, 2015. http://dx.doi.org/10.1109/icton.2015.7193651.
4
Dash, Diptimayee, and Jasmine Saini. "Linearly Graded Photonic Crystal with Improved Sensitivity for Sensing Application." In 2022 8th International Conference on Signal Processing and Communication (ICSC). IEEE, 2022. http://dx.doi.org/10.1109/icsc56524.2022.10009517.
5
Netti, M. C., J. J. Baumberg, M. D. B. Charlton, M. E. Zoorob, and G. J. Parker. "Coupling of light in graded effective index photonic crystal waveguides." In CLEO 2001. Technical Digest. Summaries of papers presented at the Conference on Lasers and Electro-Optics. Postconference Technical Digest. IEEE, 2001. http://dx.doi.org/10.1109/cleo.2001.948200.
6
Xia, Feng, Mei Wang, Meiling Liu, Wei Lv, Zan Zhang, and Maojin Yun. "Focusing on the graded negative index flat by annular photonic crystal." In SPIE Optical Engineering + Applications, edited by Shizhuo Yin and Ruyan Guo. SPIE, 2013. http://dx.doi.org/10.1117/12.2022564.
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Liu, Xu, Y. Y. Li, B. Q. Wang, and P. F. Gu. "Graded Wave-Like Two-Dimensional Photonic Crystal made of Thin Films." In Optical Interference Coatings. Washington, D.C.: OSA, 2007. http://dx.doi.org/10.1364/oic.2007.md3.
8
Panahianfar, P., and B. Rezaei. "Dynamically tunable Graded Index Photonic Crystal lens based on Dirac semimetal." In 2022 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD). IEEE, 2022. http://dx.doi.org/10.1109/nusod54938.2022.9894795.
9
Dash, Diptimayee, Jasmine Saini, Amit Kumar Goyal, and Yehia MassoudFellow. "Graded Index Nanophotonic Resonator with Improved Sensing Performance." In Frontiers in Optics. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/fio.2022.jtu4b.38.
Abstract:
The proposed work demonstrates the performance evaluation of graded index photonic crystal resonator structure using finite element method. This exhibits generation of lower energy resonating mode having 125% higher sensitivity than conventional resonator structures.
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Kumar, Ajeet, Lakshay Gautam, and Alankrit Tomar. "Design and analysis of graded rectangular-core photonic crystal fiber for terahertz communication." In Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications XII, edited by Shizhuo Yin and Ruyan Guo. SPIE, 2018. http://dx.doi.org/10.1117/12.2320912.