Dissertations / Theses on the topic 'Narrow band Filters'

In this thesis two versions of a single filter frequency masking narrow-band high-speed recursive digital filter structure, proposed in [1], have been implemented and evaluated considering the maximal clock frequency, the maximal sample frequency and the power consumption. The structures were compared to a conventional filter structure, that was also implemented. The aim was to see if the proposed structure had some benefits when implemented and synthesized, not only in theory. For the synthesis standard cells from AMS csx 0.35 mm CMOS technology were used.

Circuit designs that employ only CMOS technology are becoming more desirable than those using traditional bipolar integrated circuit technology. This technology offers a high density of MOS circuitry, good capacitor accuracy and high stability. The availability of techniques for the design and realization of precision filters in fully integrated form has many applications in signal processing VLSI circuits. The design, simulation and compensation of MOS transistor filters are presented. The MOS transistor is used as a voltage controlled resistor. The resulting "MOSFET-C" filters can then be built of MOS transistors, capacitors and operational amplifiers fabricated in MOS technology. The advantages of MOSFET-C filters over other integrated filters are discussed. Desirable MOS transistor circuit configurations for use in these filter designs are also presented. High-order, high-frequency, narrow-band bandpass filters are designed and simulated to give a systematic step-by-step design procedure for realizing MOSFET-C filters. These steps include modifying existing well established and studied filter building blocks for use in this method. The nonidealities associated with MOS transistors, especially at high frequencies, are studied and modeled for simulation. Compensation techniques for these nonidealities, together with those of operational amplifiers are presented and applied to both RC and MOSFET-C filters. A compensation scheme is developed which cancels the op amp effects in second-order filter building blocks.

Optical fibers have revolutionized telecommunications. Much of the success of optical fiber lies in its near-ideal properties: low transmission loss, high optical damage threshold, and low optical nonlinearity. The photosensitivity of an optical fiber was accidentally discovered by Hill, et al. in 1978. However, the technological advances made in the field of photosensitive optical fibers are relatively recent. This fascinating technology of photosensitive fiber is based on the principle of a simple in-line all-fiber optical filter. It has been shown that the transmission spectrum of a fiber Bragg grating can be tailored by incorporating multiple phase-shift regions during the fabrication process. Phase shifts open up ultra narrowband transmission windows inside the stop band of the Bragg grating. As a specific application, this research is focused on applying this technology in future space-based water vapor DIfferential Absorption LIDAR (DIAL) systems to improve the performance of space-based LIDAR systems by rejecting the reflected solar background. The primary goal of this research effort was to demonstrate the feasibility of using ultra narrow band fiber optic Bragg grating filters for atmospheric water vapor measurements. Fiber Bragg gratings were fabricated such that two transmission filter peaks occurred and were tunable, one peak at a 946 nm water vapor absorption line and another peak at a region of no absorption. Both transmission peaks were in the middle of a 2.66-nm stop band. Experimental demonstration of both pressure and temperature tuning was achieved and characterization of the performance of several custom-made optical fiber Bragg grating filters was made. To our knowledge these are the first optical fiber gratings made in this frequency range and for this application. The bandwidth and efficiency of these filters were measured and then these measurements were compared with theoretical calculations using a piecewise matrix form of the coupled-mode equation. Finally, an ultra narrow band water vapor DIAL filter was characterized having two pass bands less than 8 pm and peak transmissions greater than 80 percent. Such fiber optic filters are now ready for integrating into space-based water vapor LIDAR systems. More broadly, these filters have the characteristics that will revolutionized satellite remote-sensing.

In radio frequency (RF), filtering is an essential part of RF transceivers. They are employed for different purposes of band selection, channel selection, interference cancellation, image rejection, etc. These are all translated in selecting the wanted signal while mitigating the rest. This can be performed by either selecting the desired frequency range by a band pass filter or rejecting the unwanted part by a band stop filter. Although there has been tremendous effort to design RF tunable filters, there is still lack of designs with frequency and bandwidth software-tuning capability at frequencies above 4 GHz. This prevents the implementation of Software Defined Radios (SDR) where software tuning is a critical part in supporting multiple standards and frequency bands. Designing a tunable integrated filter will not only assist in realization of SDR, but it also causes an enormous shrinkage in the size of the circuit by replacing the current bulky off-chip filters. The main purpose of this research is to design integrated band pass and band stop filters aimed to perform interference cancellation. In order to do so, two systems are proposed for this thesis. The first system is a band pass filter capable of frequency and band with tuning for C band frequency range (4-8 GHz) and is implemented in 0.13 µm BiCMOS technology. Frequency tunability is accomplished by using a variable capacitor (varactor) and bandwidth tuning is carried out by employing a negative transconductance cell to compensate for the loss of the elements. Additional circuitry is added to the band pass filter to enhance the selectivity of the filter. The second system is a band stop filter (notch) with the same capability as the band pass filter in terms of tuning. This system is implemented in C band, similar to its band stop counterpart and is capable of tuning its depth by using a negative transconductance in an LC tank. A negative feedback is added to the circuit to improve the bandwidth. While implemented in the same process as the band pass filter, it only employs CMOS transistors since it is generally more attractive due to its lower cost and scalability. Both of the systems mentioned use a varactor for changing the center frequency which is a nonlinear element. Therefore, the nonlinearity of it is modelled using two different methods of nonlinear feedback and Volterra series in order to gain further understanding of the nonlinear process taking place in the LC tank. After the validation of the models proposed using Cadence Virtuoso simulator, two methods of design and tuning are suggested to improve the linearity of the system. After post layout-extraction, the band pass filter is capable of Q tuning in the range of 3 to 270 and higher. With the noise figure of 10 to 14 dB and input 1-dB compression point as high as 2 dBm, the system shows a reasonably good performance along its operating frequency of 4 to 8 GHz. The band stop filter which is designed in the same frequency band can achieve better than 55 dB of rejection with the noise figure of 6.7 to 8.8 dB and 1-dB compression point of -4 dBm. With the power consumption of 39 to 70 mW, the band stop filter can be used in a low power receiver to suppress unwanted signals. The technique used in the band stop filter can be applied to higher frequency ranges if the circuit is implemented in a more advanced silicon technology. Implementing the mentioned filters in a receiver along with other elements of low noise amplifiers, mixers, etc. would be a major step toward full implementation of SDR systems. Studying the linearity theory of varactors would help future designers identify the sources of nonlinearity and suggest more efficient tuning techniques to improve the linearity of RF electronic systems.
Master of Science

The Narrow-Band Imaging (NBI) technique allows the detection of lesions not identified with white light. Medical studies revealed that the wavelengths of 415 nm and 540 nm of the electromagnetic spectrum correspond to the peaks of hemoglobin absorptions band. The wavelength of 415 nm is located in the blue region of the electromagnetic spectrum, allowing the visualization enhancement of superficial veins. Moreover, the wavelength of 540 nm is located in the green region of the spectrum, and it is related to the visualization of sub-epithelial vessels. Initially, this work aims the design, simulation, fabrication (as well as stablish all the ideal settings for the depositions) and characterization of optical filters for the wavelength around 415 nm and 540 nm, through the application of the Fabry-Perot principle. Additionally, this work aims the investigation of two hypotheses: the first one is test the optical filters on the image sensor, and the second one is to test them on the light sources, in order to determined which adaptation technique is better for improving the image contrast of the blood vessels.
A técnica de Narrow-Band Imaging (NBI), ou imageamento por banda estreita, permite a detecção de lesões que não podem ser identificadas com a luz branca. Estudos clínicos revelaram que os comprimentos de onda de 415 nm e 540 nm do espectro eletromagnético correspondem aos picos de banda de absorção da hemoglobina. O comprimento de onda de 415 nm localiza-se na parte azul do espectro eletromagnético, o que permite uma melhor visualização de vasos superficiais. Além disso, o comprimento de onda 540 nm localiza-se na faixa verde do espectro e está relacionado com a visualização de vasos sub-epitheliais. O intuito deste trabalho é o projeto, simulação, fabricação (assim como estabelecer os parâmetros ideais para as deposições) e caracterização de filtros ópticos para os comprimentos de onda próximos de 415 nm e 540 nm, com aplicação do princípio físico de Fabry-Perot. Posteriormente, pretende-se investigar duas hipóteses: a primeira é a de testar os filtros ópticos no sensor de imagem, e o segundo é a de testá-los nas fontes de luz, para verificar qual técnica de adaptação seria melhor para aumentar o contraste entre os vasos sanguíneos.

El cartografiat Physics of the Accelerating Universe (PAU) al telescopi William Herschel (WHT) farà servir una nova càmera òptica (PAUCam) amb un gran conjunt de filtres de banda estreta per a dur a terme un cartografiat de galàxies amb determinacions fotomètriques del desplaçament al roig (photoz) de precisió quasiespectroscòpica σ(z)/(1+z ) ~ 0,0035, així com també fer un mapa de l'estructura a gran escala de l'univers en tres dimensions fins iAB < 22.523.0. A la primera part de la tesi es presenta un estudi detallat del rendiment en photoz utilitzant simulacions fotomètriques de 40 filtres equidistants de 12.5 nm d'amplada (FWHM) cadascun, amb un ~25% de solapament entre ells i que en conjunt abasten de 450 nm a 850 nm en longitud d'ona, juntament amb un sistema de filtres de banda ampla ugrizY. A continuació, presentem la matriu de migració rij, que conté la probabilitat que una galàxia dins del interval j en desplaçament al roig real es mesuria l'interval i en photoz, i estudiar el seu efecte en la determinació de les correlacions espacials entre galàxies, tant les autocorrelacions com les correlacions creuades entre diferents intervals de photoz. Finalment, també estudiem l'impacte en el rendiment de la determinació de photozs en aplicar petites variacions en l'amplada, la cobertura de longituds d'ona, etc., del conjunt de filtres, i trobem una àmplia regió en la qual els conjunts de filtres lleugerament modificats ofereixen resultats similars, deduint que el conjunt original és prou òptim. A la primera part de la tesi, es fa ús d'un tall de qualitat en la determinació dels photoz, és a dir, s’eliminen aquelles galàxies de la mostra per a les quals se sospita que l'estimació del photoz podria ser poc fiable, per així aconseguir la precisió que es necessita. A la segona part de la tesi, es mostra que l'aplicació d'aquests talls de qualitat pot esbiaixar substancialment tant les correlacions entre galàxies mesurades a cadascun del intervals en photoz com les creuades. A continuació, es desenvolupa un mètode simple i eficaç per corregir aquest efecte fent servir les mateixes dades. Finalment, s'aplica el mètode al catàleg de MegaZ, que conté al voltant d'un milió de galàxies vermelles lluminoses amb un desplaçament al roig de 0.45 < z < 0.65. Després de dividir la mostra en quatre intervals de photoz d’amplada Δz = 0.05 utilitzant l'algoritme BPZ, veiem com les nostres correccions fan que les mesures de les correlacions entre galàxies en un mateix interval i entre els intervals creuats estiguin d’acord amb les prediccions. A continuació, busquem el senyal de les oscil·lacions acústiques de barions (BAO) en els quatre intervals de photoz, amb i sense l'aplicació dels talls de qualitat, i trobem un ampli acord entre les escales BAO extretes en ambdós casos. És interessant de notar que s'observa una correlació entre la densitat de galàxies i la qualitat de les determinacions de photoz fins i tot abans que s'apliqui qualsevol tall de qualitat. Això pot ser degut a efectes observacionals no corregits que resultin en gradients correlacionats en el cel entre la densitat de galàxies i la precisió en la determinació de photozs. El nostre procediment de correcció podria, doncs, ajudar a mitigar alguns d'aquests efectes sistemàtics.
The Physics of the Accelerating Universe (PAU) survey at the William Herschel Telescope (WHT) will use a new optical camera (PAUCam) with a large set of narrowband filters to perform a photometric galaxy survey with a quasispectroscopic redshift precision of σ(z)/(1 + z) ~ 0.0035 and map the largescale structure of the universe in three dimensions up to iAB < 22.523.0. In the first part of the thesis we present a detailed photoz performance study using photometric simulations for 40 equallyspaced 12.5nmwide (FWHM) filters with a ~25% overlap and spanning the wavelength range from 450 nm to 850 nm, together with a ugrizY broadband filter system. We then present the migration matrix rij, containing the probability that a galaxy in a true redshift bin j is measured in a photoz bin i, and study its effect on the determination of galaxy autoand crosscorrelations. Finally, we also study the impact on the photoz performance of small variations of the filter set in terms of width, wavelength coverage, etc., and find a broad region where slightly modified filter sets provide similar results, with the original set being close to optimal. In the first part of the thesis we make use of a photometric redshift (photoz) quality cut, that is removing those galaxies from the sample for which one suspects that the photoz estimation might be unreliable, in order to achieve the stringent photoz precision needed. In the second part of the thesis, we show that applying these photoz quality cuts blindly can grossly bias the measured galaxy correlations within and across photometric redshift bins. We then develop a simple and effective method to correct for this using the data themselves. Finally, we apply the method to the MegaZ catalog, containing about a million luminous red galaxies in the redshift range 0.45 < z < 0.65. After splitting the sample into four Δz = 0.05 photoz bins using the BPZ algorithm, we see how our corrections bring the measured galaxy autoand crosscorrelations into agreement with expectations. We then look for the BAO feature in the four bins, with and without applying the photoz quality cuts, and find a broad agreement between the BAO scales extracted in both cases. Intriguingly, we observe a correlation between galaxy density and photoz quality even before any photoz quality cuts are applied. This may be due to uncorrected observational effects that result in correlated gradients across the sky of the galaxy density and the galaxy photoz precision. Our correction procedure could also help to mitigate some of these systematic effects.

Quasars are valuable sources for several cosmological applications. In particular, they can be used to trace some of the heaviest halos and their high intrinsic luminosities allow them to be detected at high redshifts. This implies that quasars (or active galactic nuclei, in a more general sense) have a huge potential to map the large-scale structure. However, this potential has not yet been fully realized, because instruments which rely on broad-band imaging to pre-select spectroscopic targets usually miss most quasars and, consequently, are not able to properly separate broad-line emitting quasars from other point-like sources (such as stars and low resolution galaxies). This work is an initial attempt to investigate the realistic gains on the identification and separation of quasars and stars when medium- and narrow-band filters in the optical are employed. The main novelty of our approach is the use of Bayesian priors both for the angular distribution of stars of different types on the sky and for the distribution of quasars as a function of redshift. Since the evidence from these priors convolve the angular dependence of stars with the redshift dependence of quasars, this allows us to control for the near degeneracy between these objects. However, our results are inconclusive to quantify the efficiency of star-quasar separation by using this approach and, hence, some critical refinements and improvements are still necessary.
Quasares são objetos valiosos para diversas aplicações cosmológicas. Em particular, eles podem ser usados para localizar alguns dos halos mais massivos e suas luminosidades intrinsecamente elevadas permitem que eles sejam detectados a altos redshifts. Isso implica que quasares (ou núcleos ativos de galáxias, de um modo geral) possuem um grande potencial para mapear a estrutura em larga escala. Entretanto, esse potencial ainda não foi completamente atingido, porque instrumentos que se baseiam no imageamento por bandas largas para pré-selecionar alvos espectroscópicos perdem a maioria dos quasares e, consequentemente, não são capazes de separar adequadamente quasares com linhas de emissão largas de outras fontes pontuais (como estrelas e galáxias de baixa resolução). Esse trabalho é uma tentativa inicial de investigar os ganhos reais na identificação e separação de quasares e estrelas quando são usados filtros de bandas médias e estreitas. A principal novidade desse método é o uso de priors Bayesianos tanto para a distribuição angular de estrelas de diferentes tipos no céu quanto para a distribuição de quasares como função do redshift. Como a evidência desses priors é uma convolução entre a dependência angular das estrelas e a dependência em redshift dos quasares, isso permite que a degenerescência entre esses objetos seja levada em consideração. Entretanto, nossos resultados ainda são inconclusivos para quantificar a eficiência da separação entre estrelas e quasares utilizando esse método e, portanto, alguns refinamentos críticos são necessários.

This thesis tackles issues of particular interest regarding analysis and design of passive components at the mm-wave and Terahertz (THz) bands. Innovative analysis techniques and modeling of complex structures, design procedures, and practical implementation of advanced passive devices are presented. The first part of the thesis is dedicated to THz passive components. These days, THz technology suffers from the lack of suitable waveguiding structures since both, metals and dielectric, are lossy at THz frequencies. This implies that neither conventional closed metallic structures used at microwave frequencies, nor dielectric waveguides used in the optical regime, are adequate solutions. Among a variety of new proposals, the Single Wire Waveguide (SWW) stands out due to its low attenuation and dispersion. However, this surface waveguide presents difficult excitation and strong radiation on bends. A Dielectric-Coated Single Wire Waveguide (DCSWW) can be used to alleviate these problems, but advantages of the SWW are lost and new problems arise. Until now, literature has not given proper solution to radiation on bends and, on the other hand, rigorous characterization of these waveguides lacks these days. This thesis provides, for the first time, a complete modal analysis of both waveguides, appropriated for THz frequencies. This analysis is later applied to solve the problem of radiation on bends. Several structures and design procedures to alleviate radiation losses are presented and experimentally validated. The second part of the thesis is dedicated to mm-wave passive components. These days, when implementing passive components to operate at such small, millimetric wavelengths, to ensure proper metallic contact and alignment between parts results challenging. In addition, dielectric absorption becomes significant at mm-wave frequencies. Consequently, conventional hollow metallic waveguides and planar transmission lines present high attenuation so that new topologies are being considered. Gap Waveguides (GWs), based on a periodic structure introducing an Electromagnetic Bandgap effect, result very suitable since they do not require metallic contacts and avoid dielectric losses. However, although GWs have great potential, several issues prevent GW technology from becoming consolidated and universally used. On the one hand, the topological complexity of GWs difficulties the design process since full-wave simulations are time-costly and there is a lack of appropriate analysis methods and suitable synthesis procedures. On the other hand, benefits of using GWs instead of conventional structures are required to be more clearly evidenced with high-performance GW components and proper comparatives with conventional structures. This thesis introduces several efficient analysis methods, models, and synthesis techniques that will allow engineers without significant background in GWs to straightforwardly implement GW devices. In addition, several high-performance narrow-band filters operating at Ka-band and V-band, as well as a rigorous comparative with rectangular waveguide topology, are presented.
Esta tesis aborda problemas actuales en el análisis y diseño de componentes pasivos en las bandas de onda milimétrica y Terahercios (THz). Se presentan nuevas técnicas de análisis y modelado de estructuras complejas, procedimientos de diseño, e implementación práctica de dispositivos pasivos avanzados. La primera parte de la tesis se dedica a componentes pasivos de THz. Actualmente no se disponen de guías de onda adecuadas a THz debido a que ambos, metales y dieléctricos, introducen grandes pérdidas. En consecuencia, no es adecuado escalar las estructuras metálicas cerradas usadas en microondas, ni las guías dieléctricas usadas a frecuencias ópticas. Entre un gran número de recientes propuestas, la Single Wire Waveguide (SWW) destaca por su baja atenuación y casi nula dispersión. No obstante, como guía superficial, la SWW presenta difícil excitación y radiación en curvas. El uso de un recubrimiento dieléctrico, creando la Dielecric-Coated Single Wire Waveguide (DCSWW), alivia estos inconvenientes, pero las ventajas anteriores se pierden y nuevos problemas aparecen. Hasta la fecha, no se han encontrado soluciones adecuadas para la radiación en curvas de la SWW. Además, se echa en falta una caracterización rigurosa de ambas guías. Esta tesis presenta, por primera vez, un análisis modal completo de SWW y DCSWW, adecuado a la banda de THz. Este análisis es aplicado posteriormente para evitar el problema de la radiación en curvas. Se presentan y validan experimentalmente diversas estructuras y procedimientos de diseño. La segunda parte de la tesis abarca componentes pasivos de ondas milimétricas. Actualmente, estos componentes sufren una importante degradación de su respuesta debido a que resulta difícil asegurar contacto metálico y alineamiento adecuados para la operación a longitudes de onda tan pequeñas. Además, la absorción dieléctrica incrementa notablemente a estas frecuencias. En consecuencia, tanto guías metálicas huecas como líneas de transmisión planares convencionales presentan gran atenuación, siendo necesario considerar topologías alternativas. Las Gap Waveguides (GWs), basadas en una estructura periódica que introduce un efecto de Electromagnetic Bandgap, resultan muy adecuadas puesto que no requieren contacto entre partes metálicas y evitan las pérdidas en dieléctricos. No obstante, a pesar del potencial de las GWs, varias barreras impiden la consolidación y uso universal de esta tecnología. Por una parte, la compleja topología de las GWs dificulta el proceso de diseño dado que las simulaciones de onda completa consumen mucho tiempo y no existen actualmente métodos de análisis y diseño apropiados. Por otra parte, es necesario evidenciar el beneficio de usar GWs mediante dispositivos GW de altas prestaciones y comparativas adecuadas con estructuras convencionales. Esta tesis presenta diversos métodos de análisis eficientes, modelos, y técnicas de diseño que permitirán la síntesis de dispositivos GW sin necesidad de un conocimiento profundo de esta tecnología. Asimismo, se presentan varios filtros de banda estrecha operando en las bandas Ka y V con altas prestaciones, así como una comparativa rigurosa con la guía rectangular.
Aquesta tesi aborda problemes actuals en relació a l'anàlisi i disseny de components passius en les bandes d'ona mil·limètrica i Terahercis. Es presenten noves tècniques d'anàlisi i modelatge d'estructures complexes, procediments de disseny, i implementació pràctica de dispositius passius avançats. La primera part de la tesi es focalitza en components passius de THz. Actualment no es disposen de guies d'ona adequades a THz causa que tots dos, metalls i dielèctrics, introdueixen grans pèrdues. En conseqüència, no és adequat escalar les estructures metál·liques tancades usades en microones, ni les guies dielèctriques usades a freqüències òptiques. Entre un gran nombre de propostes recents, la Single Wire Waveguide (SWW) destaca per la seua baixa atenuació i quasi nul·la dispersió. No obstant això, com a guia superficial, la SWW presenta difícil excitació i radiació en corbes. L'ús d'un recobriment dielèctric, creant la Dielecric-Coated Single Wire Waveguide (DCSWW), alleuja aquests inconvenients, però els avantatges anteriors es perden i nous problemes apareixen. Fins a la data, no s'han trobat solucions adequades per a la radiació en corbes de la SWW. A més, es troba a faltar una caracterització rigorosa d'ambdues guies. Aquesta tesi presenta, per primera vegada, un anàlisi modal complet de SWW i DCSWW, adequat a la banda de THz. Aquest anàlisi és aplicat posteriorment per evitar el problema de la radiació en corbes. Es presenten i validen experimentalment diverses estructures i procediments de disseny. La segona part de la tesi es centra en components passius d'ones mil·limètriques. Actualment, aquests components pateixen una important degradació de la seua resposta a causa de que resulta difícil assegurar contacte metàl·lic i alineament adequats per a l'operació a longituds d'ona tan menudes. A més, l'absorció dielèctrica incrementa notablement a aquestes freqüències. En conseqüència, tant guies metàl·liques buides com línies de transmissió planars convencionals presenten gran atenuació, sent necessari considerar topologies alternatives. Les Gap Waveguides (GWs), basades en una estructura periòdica que introdueix un efecte de Electromagnetic Bandgap, resulten molt adequades ja que no requereixen contacte entre parts metàl·liques i eviten les pèrdues en dielèctrics. No obstant, tot i el potencial de les GWs, diverses barreres impedixen la consolidació i ús universal d'aquesta tecnologia. D'una banda, la complexa topologia de les GWs dificulta el procés de disseny atés que les simulacions d'ona completa consumeixen molt de temps i no existeixen actualment mètodes d'anàlisi i disseny apropiats. D'altra banda, és necessari evidenciar el benefici d'utilitzar GWs mitjançant dispositius GW d'altes prestacions i comparatives adequades amb estructures convencionals. Aquesta tesi presenta diversos mètodes d'anàlisi eficients, models, i tècniques de disseny que permetran la síntesi de dispositius GW sense necessitat d'un coneixement profund d'aquesta tecnologia. Així mateix, es presenten diversos filtres de banda estreta operant en les bandes Ka i V amb altes prestacions, així com una comparativa rigorosa amb la guia rectangular.
Berenguer Verdú, AJ. (2017). Analysis and design of efficient passive components for the millimeter-wave and THz bands [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84004
TESIS

Thesis (M.S. in Combat Systems Technology)--Naval Postgraduate School, December 2004.
Thesis advisor(s): Alfred W.Cooper, Gamani Karunasiri. Includes bibliographical references (p. 91-92). Also available online.

Les filtres spectraux à réseaux résonants, ou GMRF (Guided-Mode Resonance Filters), sont une nouvelle génération de filtres à bande étroite et constituent une alternative très prometteuse aux filtres conventionnels multicouches Fabry-Pérot. Le pic de résonance d'un GMRF peut être très fin spectralement et de longueur d'onde de centrage accordable en fonction de l'angle d'incidence. Ces propriétés sont particulièrement importantes pour la spectroscopie. Les travaux antérieurs ont permis de mettre en œuvre une structure originale comportant deux réseaux 1D croisés. Les performances de ce filtre surpassent celles des filtres conventionnels par leur réponse spectrale subnanométrique, leur accordabilité, et leur capacité à s'affranchir de l'influence de la polarisation de l'onde incidente sous incidence oblique. Le but de ce travail est d'explorer les performances ultimes de ce type de dispositif en termes de résolution et taux de réjection, par une approche mêlant théorie, technologie et caractérisation. Nous présentons des résultats expérimentaux d'un filtre en réflexion indépendant de la polarisation, accordable sur 40 nm avec 8.3nm/° d'accordabilité, ayant une réflexion de 10-3 sur une plage de 90nm en dehors de la résonance et un facteur de qualité supérieur à 5000
Guided Mode Resonance Filters ( GMRF ) are a new generation of narrowband optical filters and are a very promising alternative to conventional multilayer Fabry-Perot filters. The resonance peak of GMRF can be spectrally extremely thin and with a centering wavelength tunable according to the angle of incidence of the light. These properties are particularly important for spectroscopy. Previous works have helped to implement an original structure with two 1D crossed gratings. The performance of this filter overpasses those of conventional filters in their spectral subnanometric response, tunability and their ability to overcome the influence of the polarization of the incident wave under oblique incidence. The aim of this work is to explore the final performances of such devices in terms of resolution and rejection rate, thanks to an approach combining theory, fabrication technology and characterization. We present experimental results of a polarization independent reflective filter, tunable over 40nm with a tunability of 8.3nm / °, having a reflection of 10-3 on a 90nm range outside the resonance and a quality factor over 5000

碩士
逢甲大學
資訊電機工程碩士在職專班
96
In the RF front-end of a modern communication system. Bandpass filter is very important component in the system. We proposed one filter which is center frequency at 2.4 GHz Narrow CPW filter, CPW main characteristic that it is a transmission line of a really single level and signal and ground are on the same level, This make series connection, circuit of component and connect in parallel very easy, it need not transmit like microstrip line must have via hole.Dispensing with the vertical trouble that bored a hole has not only reduced the expenses of the circuit of making. So will study coplanar waveguide to design the Narrow band(3%) bandpass filter in dissertation, prevents during the different frequency channel Crosstalk.The BPF used first order CPW and second order CPW study circuit and characteristic and performance.We used the bend in the skill produces the coupling improves the circuit performance,the compact circuit is again parallel compact circuit achieves the narrow.

by Meng Wei.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.
Includes bibliographical references (leaves 115-119).
Abstracts in English and Chinese.
Abstract
Acknowledgements
Table of Contents
Chapter 1. --- Introduction --- p.1
Chapter 1.1 --- Overview of Microwave Filter --- p.1
Chapter 1.2 --- Introduction to Synthesis and Diagnosis of Generalized Chebyshev Coupled Resonator Filters --- p.3
Chapter 1.3 --- Original Contributions --- p.5
Chapter 1.4 --- Thesis Organization --- p.6
Chapter 2. --- Fundamental Theory --- p.7
Chapter 2.1 --- Generalized Chebyshev Polynomial --- p.7
Chapter 2.2 --- Cross Coupled Resonator Network --- p.19
Chapter 2.3 --- N x N Coupling Matrix Synthesis --- p.22
Chapter 2.4 --- Similarity Transformation --- p.28
Chapter 2.5 --- N + 2 Transversal Network Synthesis --- p.34
Chapter 2.6 --- Example --- p.39
Chapter 2.7 --- Summary --- p.46
Chapter 3. --- Analytical Diagnosis of Narrow-Band Coupled Resonator Filters --- p.47
Chapter 3.1 --- Introduction --- p.47
Chapter 3.2 --- Extended Realizability Conditions --- p.50
Chapter 3.3 --- Filter Circuit Model Extraction with Finite Q Value --- p.57
Chapter 3.4 --- Diagnosis of a Dual-Mode Circular Waveguide Filter --- p.64
Chapter 3.5 --- Diagnosis of a In-Line Waveguide Filter --- p.69
Chapter 3.6 --- Application in Tuning a Sixth Order Dual-Mode Filter --- p.74
Chapter 3.7 --- Future Work --- p.82
Chapter 3.8 --- Summary --- p.83
Chapter 4. --- Hybrid Synthesis of Microwave Coupled Resonator Filters --- p.84
Chapter 4.1 --- Introduction --- p.84
Chapter 4.2 --- A Hybrid Approach --- p.86
Chapter 4.3 --- Matrix Transformations --- p.90
Chapter 4.4 --- Application of Proposed Method --- p.94
Chapter 4.5 --- Future Work --- p.100
Chapter 4.6 --- Summary --- p.101
Chapter 5. --- Conclusion --- p.102
Appendix --- p.104
References --- p.115
Author's Publications --- p.120

碩士
國立臺灣科技大學
電子工程系
95
The filters play an important part in mobile device of wireless communication, cellular phone, global positioning system (GPS) and signal processing systems. There are many different kinds of specification of wireless communication put into a device in the market that will be usually required and the bandwidth efficiency describes the ability of a modulation technique to accommodate data within a limited bandwidth. The microwave filters are widely used in all radio system in order to discriminate between wanted and unwanted signal frequency. Traditionally, most of the filters are made by passive networks that such as waveguide, transmission line or discrete lumped elements. But ,due to keep improvement of monolithic microwave integrated circuit (MMIC) process technology, more and more system utilize the active filters and it is the trend to reduce the size of mobile device so it also is the reason to use the active filters to instead of the passive filters. Because the advantages of active filters are small size, compatibility with other ICs and low losses in narrow bandwidth designs. The thesis plays a important to design a high frequency and narrow bandwidth filters and design concept to be use negative resistance compensation technique to compensate the losses that are made by elements of circuit. We design the resonator that consists of an active capacitance circuit together with a conventional inductor and the active capacitance circuit was made of a field-effect transistor that exhibits negative resistance as well as capacitance. It can, therefore, compensate the loss of an inductor. The element values of the circuit and the computer simulation for the circuit performance are given. The EDA analysis results show that this active filter does have the narrow band property, and gain of more than at center frequency and the attenuation of more than at are achieved. By the way, a 1.9GHz active narrow band-pass filter fabricated on FR4 substrate is implemented to ensure the circuit topology used throughout this thesis is applicable.

Due to advances in high-density low-cost VLSI and communication technology, digital filtering and signal processing are being widely used for real-time signal processing applications. Given the filter specification, choosing the best filter structure for a given application is not a trivial task. The choice of a particular filter structure depends on many factors such as sensitivity to finite word-length quantization effects, hardware complexity and power consumption. The objective of this thesis is to examine digital IIR (Infinite Impulse Response) filter structures for the VLSI implementation of narrow-band sharp-transition filters. This thesis examines several different digital IIR filter structures; namely cascade form IIR filter, five different digital lattice filters and lattice wave digital filter structures. For fixed-point implementation, the sensitivity, round-off noise properties and the scaling of these filter structures are described and analyzed. These filter structures are compared with respect to the architectural complexity, the sensitivity to coefficient quantization, the round-off noise due to product quantization and the signal dynamic range. Fixed-point implementation simulations using two's-complement arithmetic are carried out for a number of narrow-band sharp-transition digital low-pass filters.
Graduation date: 1995

碩士
國立中央大學
光電科學研究所
90
Abstract DWDM thin film filters have been widely used in fiber-communication system. In order to have a stable communication, it’s necessary to do reliability measurement and improve the quality. The main subject in this study is to construct a spectral measurement system of band-pass filters in fiber-communication system. After system constructed and system error analysis, we conclude that the wavelength resolution width must be smaller than one-tenth of the FWHM of the bandpass filters. We have measured the TSCW (Temperature Shift of Central Wavelength) of the DWDM thin film filters deposited on two kinds of substrate with different thermal expansion coefficients (83´10-7/oC and 133´10-7/oC), and get the following the results: (1) Water absorption effect which is deposited by IAD (Ion Assisted Deposition ) or IBSD (Ion Beam Sputtering Deposition ) technology is no longer the main effect for TSCW of the DWDM thin film filters. (2) We can predict that the zero TSCW of the DWDM thin film filter deposited on the substrate with thermal expansion coefficient is 133´10-7/oC under such IBSD parameters (Main: BV=1100V (current density»260mA/cm2), IAD:BV=400V (current density»40mA/cm2)). (3) We can get the value of some thermal coefficients of the bandpass filter, such as thermal expansion coefficient, Possion’s ratio, refractive-index of temperature coefficient of the bandpass filter.

碩士
國立中興大學
材料科學與工程學系
96
The main objective of this thesis is to study on how to improve the color-purity of LEDs, design and develop the optical filter to apply on RGB LEDs. Using measuring equipments to measure the spectrum and check the effects of improving the color-purity of LEDs. And estimating the effects on color gamut after improving the color-purity of LEDs by check the space on the CIE chromaticity coordinates. The standard color of space that had been approved by the National Television System Committee (NTSC) is used as the reference and defined as 100%. About the FWHM (Full Width Half Maximum) of Green light is too wide and there is mixed-zone between blue and green light in the RGB LEDs spectrum, we design green light narrow band-pass filter, mixed-zone band-stop filter and RGB narrow band-pass filter by optical design software. And we use the materials of TiO2 and SiO2 to make the filter film by thin film evaporation equipment. From the experiment, we have found the results as following: 1. The RGB-narrow-band-pass-filter is the best one for improving the LED color purity, and the 0.4mm-glass is the best substrate. 2. The FWHM of red, green and blue light were decreasing under 17nm in axial light measurement after RGB-narrow-band-pass-filter apply on LEDs, and the range of color gamut was increasing from 118.41% to 132.56% according to NTSC standard. 3. The limitation of this study is that the filters in our experiments can not be effective for lateral light because of the light leaking from cross-section of LED chip and the different incident angle of light.

碩士
國立中央大學
光電科學研究所
97
The research point in this paper is the designs of antireflection coatings and narrow band pass filters using negative refraction index materials (NIMs). First, the properties of NIMs and the modification of electromagnetism are discussed to illustrate how to design optical thin film filters using those properties. The thin film matrix and admittance locus methods have been applied to design antireflection coatings and narrow band pass filters. Finally, the special optical properties of antireflection coatings and narrow band pass filters with NIMs are analyzed. Normally, the phase of optical thin film is increased when the thickness of optical thin film is increased. However, the phase of NIM is decreased as the thickness of the film is increased to affect the whole phase decreased. In other words, the whole phase is compensated. The result affects the spectra of the thin films have less sensitivity in wavelength and incident angle. If the antireflection coatings are designed with NIMs, the low reflection range is broader than without NIM and the average reflection is lower, too. Another application for NIM is to replace the spacer layer using NIM to be a new type of narrow band pass filter. As the whole phase changes, the central wavelength is different. Hence the narrow band pass filter can be designed as a wavelength-non-shift filter with incident angle based on the relationship of incident angle and central wavelength.

碩士
國立中央大學
光電科學與工程學系
101
With the advance of science and technology, optical thin film coating has been applied extensively in various optoelectronic devices. This is a very important issue to fabricate high quality optical thin films. The optical monitor is extremely important in precision interference coatings, since it provides error compensation during the fabrication of each thin-film layer. In the article, we provide a new monitoring method－reflection coefficient loci monitoring which combined the advantages of single-wavelength and broadband monitoring. The single-wavelength monitoring has a clear deposition termination mechanism, and broadband monitoring can obtain many wavelengths at the same time. This new monitoring method use the real-time broadband spectrum measurements to extract the real-time thin film refraction index and thickness. We use the reflection coefficient loci monitoring to fabricate narrowband pass filter (NPF). In the experimental results, we know that the central wavelength of NPF shift less than 0.28 nm, the different of transmittance at the central wavelength is lower than 3.47% closer to the design by the proposed monitoring method. Besides, we also discuss whether the real-time reflection Coefficient loci monitoring can compensate the errors due to refractive index variation. In the analysis, it shows that the central monitoring wavelength shift less than 0.2 nm, the different of transmittance at the central wavelength is lower than 0.16% compared with the design.

碩士
國立成功大學
機械工程學系
89
An analytical model is developed in the article to evaluate the effects of temperature and humidity change as well as stress level on the optical characteristics of three-cavity subnanometer bandpass filters made by TiO2 and SiO2 film materials through ion-assisted deposition (IAD) in consideration of the coupled photo-elastic and hygro-thermo-optical effects. A more realistic stress analysis, which is capable of considering the effects of intrinsic and thermal stresses, bending moment as well as non-uniform temperature rise, is proposed and formulated first. A variety of factors including the errors of film thickness, change of refractive index and film thickness due to temperature rise, humidity change as well as the stress level, are then considered to evaluate their individual influence on optical characteristics of the bandpass filters. The results show that the change of film thickness due to temperature rise and stress plays a significant role on center wavelength shift. A protective coating on filter has significant effort to reduce the influence of humidity on center wavelength shift. Moreover, a remarkable degradation of transmission curve due to non-uniform temperature rise can be observed.

碩士
國立交通大學
光電(科學)研究所
82
A new design for optical narrow-band filter is investigated by using substrate-mode holograms(SMHs). It combines transmission and reflection-type SMHs cascading up and down. This device has the advantages of narrow-linewidth(subnarometer), high transmittance (>90%), tunable central wavelength and normally incident and output coupling of the structure. Its applications include the detection of Sun's spectrum in solar astronomy, wavelength-division-multiplexing technology(WDM) in optical communication and wavelength selector for optical interconnection . Computer simulation of necessary conditions and experiment results with free space recording technology of short wavelength is presented. In our experiments, we also confirmed the filtering effect by light passing the combination of the two-type SMHs.

碩士
大同大學
通訊工程研究所
89
In this thesis, design of a new miniaturized narrow-band filter is discussed. It composes of four slip-ring step-impedance resonators. The resonant frequency of each resonator is firstly determined, then, the coupling coefficients between any two resonators and the external quality factor are extracted. A commercially available software package (IE3D version 5.3) was used in this survey. Filters designed in this thesis are well prepared for 2.45GHz ISM-band use. The fractional bandwidth is around 4%. Two type of filters are studied-one is used to realize the Chebyshev function, and the other the elliptic function. The filters can be achieved with a 4-pole structure. The filter response could be composed of a coupling matrix. Each element is represented the coupling coefficient between two resonators. We expect the circuit area could be reduced effectively. Finally, we measure the filter response with the network analyzer HP8510C, and compare the measured results with the theoretical and simulation response. The measured insertion loss is around —2 dB, and the fractional bandwidth is about 4% to 5%. It is close to the theoretical response.

碩士
國立中央大學
光電科學與工程學系
102
The thesis is consisted of two parts, the first part is about fabrication of CdS quantum dots by chemical bath deposition (CBD), in which we improve the size distribution of quantum dots, QDs, uniformity of crystalline phase. The optimized parameters are 3 minutes process time, 1.2 M ammonia, and 300˚C post-annealing with 30 minutes which results in the quantum dots of 2.5 nm with high performance of crystallization. The second part is about the fabrication of narrow band pass filter, NBPF, with spacers including quantum dots. We successfully fabricate QDs-NBPF with the 3, 4, 5 pair number by Ion-Beam Sputtering Deposition and spin coating. And then with the 325 nm He-Cd laser pumping, the transmission of QDs-NBPF with 3 pairs, 4 pairs and 5 pairs at the center wavelength are 152.2 %, 418.3 % and 534.0 %, respectively. Finally we calculate the equivalent extinction coefficient k of the spacer of the QDs-NBPF by fitting the transmission intensity on the center wavelength.

碩士
國立交通大學
電子物理系
91
In this thesis, we propose a method to achieve a narrow band-pass optical filter using cascaded Distributed-Bragg-Reflectors (DBRs) and optical cavity, which construct a Fabry-Perot-like interferometry. Firstly, we analyze the traditional thin-film coating multi-layer optical filter by the use of transfer matrix method. The results can give us a guide how to design an optical narrow band-pass filter with nearly rectangular transmission spectrum. Secondly, by using the coupled-wave analyses of a volume hologram, we derive the scattering matrix method to analyses the diffraction properties of a reflection-type volume hologram. It provides us an extended matrix method to investigate the transmission characteristics of different cascaded structures of the volume holographic gratings. In experiment, we use PQ/PMMA photopolymer to fabricate volume holographic reflection-type gratings, and then the resonance cavities are fabricated by using thermal coating of MgF2 thin film. The theoretical and experimental results show that it is possible to achieve a narrow band-pass optical filter by using cascaded volume holographic gratings. However, the grating length, cascading structure and optical resonance cavity length must be chosen carefully such that the phase condition of Fabry-Perot-like structure can be matched.

碩士
國立成功大學
電機工程學系碩博士班
97
This thesis proposes the modified EMI filter for suppressing narrow-band conducted noise. The circuit consists of sorts of passive elements, including the induction winding, capacitors and resistors. By combining the passive elements in series and parallel to produce resonance, the modified EMI filter is made to achieve the narrow-band conducted noise suppression. By designing and adjusting ideal parameters of elements to produce resonance, it achieves to reduce common-mode noise current and differential-mode noise current efficiently of the narrow-band conducted suppression without affecting broad-band conducted noise suppression. This paper further provides to prove the modified EMI filter for suppression of narrow-band conducted noise, which can effectively reduce electromagnetic interference from the narrow-band conducted noise by theoretical analysis added with circuit simulations and results of measured experiments.

碩士
國立臺灣科技大學
電子工程系
99
In this thesis, we propose an approach to design and implement networks with capability of being microwave filters. Using z-domain technique and parallel two-section stubs to design a narrow bandpass filter. This method present a z-domain transform technique to design an arbitrarily pre-defined filter is implemented by using equal-length transmission lines. Parallel open stubs placed on both sides of the serial transmission line are used to induce a passband that forms a narrow bandpass filter. The filters are implemented with serial transmission lines, parallel open one-section stub, parallel short one-section stub, and parallel two-section stubs. The filter responses of defined by design can be implemented with the configuration of transmission lines for microwave application. The simulated results show that the passband is narrow, and the filter can suppress the higher order harmonics. Eventually, experimental results are presented to illustrate the validity of the two design method.

碩士
國立中央大學
光電科學與工程學系
104
Optical thin film is an important technology and it is widely used in daily life. For example, the anti-reflection (AR) coating on the glasses and camera lens. Owing to achieve the design properties of optical film, the optical monitoring assisted deposition is an effective method. In the coating process, the changes of chamber environment and temperature will cause changes in refractive index of materials. If the refractive index is fixed in the monitoring process, the results will different to the design. In this research, the real-time refractive index was calculated by the transmittance information, and applies to the reflection coefficient monitoring to deposit the narrowband filters. The error of monitoring wavelength is less than 0.5 nm, and the difference of transmittance and FWHM is less than 1.5 percent and 1.4 nm, respectively. We also apply the method to deposit the dual-cavity narrowband filter. The error of monitoring wavelength is 0.15 nm, the difference of transmittance and FWHM is 2.18 percent and 0.2 nm, respectively. In conclusion, the reflection coefficient monitoring applied the real-time refractive index could been a very high accuracy and repeatability method.

博士
國立成功大學
微電子工程研究所
105
The dissertation is divided into four sections, comprising: (a) design of tri-band bandpass filter (BPF) by using asymmetric stub-loaded resonators (ASLR); (b) design of low-pass filter (LPF) with ultra broad stopband characteristic; (c) design of compact ultra-wideband (UWB) BPF; (d) design of dual-band BPF with narrow-bandwidth and wide-bandwidth responses. Firstly, introductions about the operation of wireless communication system and relative protocol are proposed in this research. Moreover, the feature of filters in the wireless communication system and the basic transmission line theory are discussed. Secondly, a tri-band BPF, constructed by ASLRs, is proposed. This ASLR is constructed by tapping a stub-loaded on the other uniform microstrip line. By properly tuning the electrical length ratios of the ASLRs (α and γ), the spurious modes of ASLR are controlled easily to form a tri-band response. In addition, a resonant chart of ASLR is provided to find the frequency of each spurious mode accurately. Thirdly, a LPF, constructed by rectangular stub loaded resonator and open-circuited stubs, is proposed. The rectangular stub loaded resonator consists of a parallel coupled line and a rectangular stub patch, and it creates multiple transmission zeros at higher frequency side to form a low-pass response. It is noted that the cutoff frequency of rectangular resonators is dominated by the electrical length ratio and impedance ratio. Fourthly, two UWB BPFs, basically constructed by rectangular stub loaded resonator, are fabricated and proposed. The resonant modes of one UWB BPF are excited by adopting parallel coupled line and rectangular stub loaded resonator, additionally, multiple transmission zeros created by rectangular stub loaded resonator are used to eliminate interference at the higher frequency side. And the resonant modes of the other UWB BPF are excited by using the mode-exciting technology. By properly tuning the electrical length ratio of the stub and parallel coupled-lines, a controllable resonant mode is excited and two transmission zeros are created in accordance with the results of imaginary-admittance analysis. Finally, a dual-band BPF, constructed by stepped-impedance ring loaded resonator (SIRLR) and rectangular stub loaded resonator (RSLR), is fabricated and proposed. Based on even- and odd-mode analysis, the properties of SIRLR is analyzed and predicted. Herein, three parameters (two electrical length ratios and one impedance ratio) are defined and used to control the resonant modes of SIRLR. Moreover, Three transmission zeros, created by RSLR, are located near the passband edge to improve the band selectivity and achieve a sharp cutoff skirt. The fabricated dual-band BPF exhibits good performance, including a narrow passband at 2.4 GHz, a wide passband from 3 GHz to 5GHz, low insertion loss, high passband selectivity, and broad stopband region. The designed dual-band bandpass filter are fabricated and measured, and the measured results match the theoretical prediction.

碩士
大葉大學
電機工程學系碩士班
93
ABSTRACT 　　Narrow-band microstrip cross-coupled band-pass filters based on the quadruplet geometry are designed for wireless-communication applications. We have fabricated the high-Tc superconducting filters by pattering YBa2Cu3Oy (YBCO) films deposited on LaAlO3 substrates. The flux pinning in YBCO resonators is increased with an artificial magnetic lattice of La0.7Sr0.3MnO3 (LSMO) pinning dots. The 4-pole 15-mm-square filter has a pair of transmission zeros near the pass-band edge, a ~2.173-GHz center frequency with a ~9.5-MHz bandwidth and a ~3.78-dB minimum insertion loss at 77 K. With a LSMO bulk and an applied field of 200 Oe, the center frequency (fc) shifts to 2.161 GHz and the insertion loss increases to 4.76 dB. This increase of insertion loss is attributes to variation of magnetic-coupling coefficient in filter. The results are discussed and compared with that of an identical YBCO filter without LSMO pinning dots. The influences of the flux pinning on filter performance are discussed .

碩士
國立臺灣大學
電信工程學研究所
95
In this thesis, a tunable inductorless CMOS narrow-band bandpass filter at UHF (ultra-high-frequency, 300MHz-3GHz) band is presented. Issues related to active-inductor design and filter design procedure is discussed in detail. The filter is fabricated in 0.18μm CMOS process, measured an insertion loss of 0.1dB, a return loss of 18dB and a 0.51dB in-band ripple with a 436MHz center frequency and 24MHz bandwidth. The filter occupies a chip size of 333 x 653 μm2, with a -27.1dBm input 1dB compression point , a 17.6dB noise figure and a 62.5 mW power consumption.

碩士
國立中央大學
光電科學研究所
89
Recently, DWDM technology has been playing an important role in the fiber-optic communication systems. Narrow Band Pass Filter is the essential device of a DWDM system. All filters must provide many standard properties﹐so it is difficult to fabricate. In the dissertation﹐we use Ta2O5 and SiO2 films to design the Narrow Band Pass Filter. We also choose process﹐build Dual Ion Beam Deposition System﹐and find out the optimum deposition parameters to fabricate subnanometer bandwidth Narrow Band Pass Filter. Several filters have been successfully fabricated and analyzed.

碩士
國立雲林科技大學
電子工程與資訊工程技術研究所
87
The optical fiber communication system has introduced for a period of time. As time goes on, people have more and more requirement for the application such as Internet access, high-quality videoconferencing and multimedia traffic. Dense wavelength division multiplexing（DWDM）is currently the leading technology in transmission links. In DWDM system each channel is related to a different wavelength, channel manipulations and particularly channel selection require optical wavelength selection（i.e., optical filtering）. The purpose of this paper is to investigate narrow band all-dielectric Fabry-Perot optical interference filters, which are used to select required wavelength signal for each channel to transmit and/or receive. Besides, we have investigated the optical characteristics of Ta2O5(92%)/TiO2(8%) film. The design specification of the filter is: bandwidth less than 1nm, transmittance loss less than 1db, and the bandwidth for 30db down less than 2nm, design incident angle is 00. The materials using in design and simulation are following : the high refractive material TiO2 (nH=2.15) and the low refractive material SiO2 (nL=1.435). The substrate and incidence medium is glass(ns=1.52) and air(n0=1) respectively. By the simulation of various multilayer systems and analyzing the influence of layer thickness and refractive index deviation, we obtain the conclusion as below: 1. Except for type IV ( BW30db=2.71nm>2nm) and type VII (BW30db=2.15nm>2nm), the remainder are valid, 2. In order to keep the yield up to acceptable level, the error of film thickness and refractive index must keep as low as 0.03% and 4% respectively.

碩士
國立交通大學
電子研究所
107
We study the absorption characteristics of carbon dioxide gas in infrared region and the mechanism behind non-dispersive infrared measurement. Based on the theoretical analysis, we observe that when we shift the central frequency of the filter in sensor to the specific position of the absorption spectrum of gas and reduce the bandwidth of filter narrower than that of absorption bandwidth, it can enhance the sensitivity of gas sensor. By designing the distributed bragg reflectors as reflection layer, we fabricate a Fabry-Perot resonance cavity to achieve the narrow-band filter. We simulate a filter centered in carbon dioxide absorption spectrum with full width at half maximum(FWHM) of 15nm. We can find that the central frequency of the filter will blueshift with incident angle increasing. We fabricate the narrow-band filter and measure the transmission and reflection spectrums. The measurement result is consistent with the simulation in the central frequency variation with the incident angle. The absorption intensity ratio is also enhanced from 16.2% to 34%.

碩士
中華大學
電機工程學系碩士班
90
In this paper, we have used the numerical method of electro -magnetic to simulate optical waveguide filter, and obtained a high performance bandpass filter. However, we analyze the model of optical filter are the buried rectangular waveguide filter, embedded rectangular waveguide filter and elliptical core optical fiber filter. Their size are very small. Main theory, which photonic crystal is defined by a 1-D periodical array of SiO2 holes in waveguide. In material, the waveguide consists of a silicon that are made within a SiO2. The photonic crystal allows strong field confinement within Si Waveguide and enable photonic crystals to be made with large PBG’s. Here we report analyses of microcavity resonances in photonic bandgap structure. The microcavity has a resonance at a wavelength of 1.55μm, a high quality factor 250 and a modal volume of (λ/2n)3. In this work, we have used the FEM(HFSS) software, the effective dielectric constant method and network analysis method for multilayer dielectric waveguide to simulate photonic bandgap filter.

碩士
國立中央大學
機械工程研究所
90
In this thesis the reliability of narrow-band-pass filter is investigated. Since during the coating process either or both of the layer thickness and material refractive index are considered to be statistical varied. In the study it is found that there exists as least a minimum numbers of layers above which the function of narrow-band-pass filter can be guaranteed. Such number of layers depends on the statistical variance of thickness or/and refractive index. However as the variance becomes large there may not exists such minimum layers.