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Espe, Burt Lann. "MATLAB simulation of a distributed feedback (DFB) laser with chirp effects." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA297053.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, December 1994."December 1994." Thesis advisor(s): John P. Powers,Randy L. Borchardt. Includes bibliographical references. Also available online.
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Yu, Zhou. "Optical Properties of Deoxyribonucleic Acid (DNA) and Its Application in Distributed Feedback (DFB) Laser Device Fabrication." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1154706431.
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Moore, Jeanne. "TRANSPORTATION OF THE RF SPECTRA OVER FIBER: A WORKING SYSTEM." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606790.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThis paper presents the results of installing a distributed feedback (DFB) laser transmitter and the appropriate optical receiver in an operational site. Frequencies from 1435 to 2400 megahertz are transported intact from a remote site to a local site. From the theoretical calculations, 10 dB of dynamic range may need to be recovered by the use of an automatic gain circuit. The actual device is a delight, needing no additional circuitry to meet specifications. Predictions of performance were made from calculations. The installed system was measured for 1 dB compression point and for figure of merit.
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Shen, Yangfei. "Coupled Wave Analysis of Two-Dimensional Second Order Surface-Emitting Distributed Feedback Lasers." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1461713975.
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Dupont, Tiphaine. "Réalisation de sources laser III-V sur silicium." Phd thesis, Ecole Centrale de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00604962.
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Le substrat SOI (Silicon-On-Insulator) constitue aujourd'hui le support de choix pour la fabrication de fonctions optiques compactes. Cette plateforme commune avec la micro-électronique favorise l'intégration de circuits photoniques avec des circuits CMOS. Néanmoins, si le silicium peut être utilisé de manière très avantageuse pour la fabrication de composants optiques passifs, il présente l'inconvénient d'être un très mauvais émetteur de lumière. Ceci constitue un obstacle majeur au développement de sources d'émission laser, briques de constructions indispensables à la fabrication d'un circuit photonique. La solution exploitée dans le cadre de cette thèse consiste à reporter sur SOI des épitaxies laser III-V par collage direct SiO2-SiO2. L'objectif est de réaliser sur SOI des sources lasers à cavité horizontale permettant d'injecter au moins 1mW de puissance dans un guide d'onde silicium inclus dans le SOI. Notre démarche est de transférer un maximum des fonctions du laser vers le silicium, dont les procédés sont familiers au monde de la micro-électronique. Dans l'idéal, le III-V ne devrait être utilisé que comme matériau à gain ; la cavité laser pouvant être fabriquée dans le silicium. Mais cette ligne de conduite n'est pas forcément aisée à mettre en œuvre. En effet, les photons sont produits dans le III-V mais doivent être injectés dans un guide silicium placé sous l'épitaxie. La difficulté est que les deux matériaux sont séparés par plus d'une centaine de nanomètres d'oxyde de collage faisant obstacle au transfert de photons. Le développement de lasers III-V couplés à un guide d'onde SOI demande alors de nouvelles conceptions du système laser dans son ensemble. Notre travail a donc consisté à concevoir un laser hybride III-IV / silicium se pliant aux contraintes technologiques du collage. En s'appuyant sur la théorie des modes couplés et les concepts des cristaux photoniques, nous avons imaginé, réalisé, puis caractérisé un laser à contre-réaction distribuée hybride (en anglais : " distributed feedback laser ", laser DFB). Son fonctionnement optique original, permet à la fois un maximum de gain et d'efficacité de couplage grâce à une circulation en boucle des photons du guide III-V au guide SOI. Sur ces dispositifs, nous montrons une émission laser monomode (SMSR de 35 dB) à température ambiante en pompage optique et électrique pulsé. Comme attendu, la longueur d'onde d'émission est dépendante du pas de réseau DFB. Les lasers fonctionnent avec une épaisseur de collage de silice de 200 nm, ce qui offre une grande souplesse quant au procédé d'intégration. Tous les lasers fonctionnent jusqu'à des longueurs de 150 μm (la plus petite longueur prévue sur le masque). Malgré les faibles niveaux de puissances récoltés dans la fibre lors des caractérisations, la prise en compte des pertes optiques induites pas les coupleurs fibres nous indique que la puissance réellement injectée dans le guide silicium dépasse le milliwatt. Notre objectif de ce point de vue est donc rempli. Malheureusement le fonctionnement des lasers en injection électrique continue n'a pas pu être obtenu dans les délais impartis. Cependant, les faibles densités de courant de seuil mesurées en injection pulsée (300A / cm2 à température ambiante sur les lasers de 550 μm de long) laissent présager un fonctionnement prochain en courant continu.
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Van, Dommelen Ronnie Francis. "Bistable distributed feedback laser diodes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0020/MQ48293.pdf.
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Todt, René. "Widely tunable laser diodes with distributed feedback /." München : Walter-Schottky-Institut, Technische Universität München, 2006. http://opac.nebis.ch/cgi-bin/showAbstract.pl?u20=3932749790.
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Hadeler, Oliver. "Distributed feedback fibre laser strain and temperature sensors." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/46100/.
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This thesis presents the development of two new types of polarimetric distributed feedback (DFB) fibre laser sensors for simultaneous strain and temperature measurements. These fibre Bragg grating (FBG) based sensors offer strain and temperature measurement accuracies of ±0.3 - ±15 με and ±0.04 - ±0.2°C which are suitable for many applications. The main advantage of these DFB fibre laser sensors over other FBG based sensors is the simplicity of their interrogation system. The first type of sensor operates stably in a single longitudinal mode which splits into two orthogonally polarised modes. This sensor utilises the wavelength of one polarisation mode and the RF beat frequency between the two polarisation modes. The system complexity is reduced to a minimum in the dual longitudinal mode polarirnetric DFB fibre laser sensor which utilises the RF beat frequencies between two longitudinal modes and their associated orthogonal polarisations, therefore requiring only a simple and cost effective frequency counter. -ions and pump excited state absorption into account. An extended version of this model incorporates, for the first time, self-heating in DFB fibre lasers which is caused by non-radiative decays. The performance of DFB fibre lasers employed in telecommunication applications is likely to benefit from these modelled results, which are also verified by experimental data.
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Pang, Wing Chung. "Ultrashort pulse generation with a distributed feedback dye laser." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47607.
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Kao, Tsung-Yu. "Surface-emitting distributed feedback terahertz quantum-cascade phase-locked laser arrays." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/54235.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 111-114).
A new approach to achieve high-power, symmetric beam-pattern, single-mode THz emission from metal-metal waveguide quantum-cascade laser is proposed and implemented. Several surface-emitting distributed feedback terahertz lasers are coupled through the connection phase sectors between them. Through carefully choosing the length of phase sectors, each laser will be in-phase locked with each other and thus create a tighter beam-pattern along the phased-array direction. A clear proof of phase-locking phenomenon has been observed and the array can be operated in either in-phase or out-of-phase mode at different phase sector length. The phase sector can also be individually biased to provide another frequency tuning mechanism through gain-induced optical index change. A frequency tuning range of 1:5 GHz out of 3:9 THz was measured. Moreover, an electronically controlled "beam steering" device is also proposed based on the result of this work. This thesis focuses on the design, fabrication and measurement of the surface-emitting distributed feedback terahertz quantum-cascade phase-locked laser arrays.
by Tsung-Yu Kao.
S.M.
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Saxena, Bhavaye. "Noise Characteristics for Random Fiber Lasers with Rayleigh Distributed Feedback." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31766.
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Frequency and intensity noise are characterized for Erbium-Doped Fiber and Brillouin random lasers based on Rayleigh distributed feedback mechanism. We propose a theoretical model for the frequency noise of an Er-doped fiber random lasers using the property of random phase modulations from multiple scattering points in ultra-long fibers. We find that the Rayleigh feedback suppresses the noise at higher frequencies by introducing a Lorentzian envelope over the thermal frequency noise of a long fiber cavity. The theoretical model and measured frequency noise agree quantitatively with two fitting parameters. A similar model, which also includes additional acoustic fluctuations and a distributed gain profile in the fiber, has been speculated for the Brillouin random laser. These random laser exhibits a frequency noise level of < 6 Hz^2/Hz at 2 kHz, which is lower than what is found in conventional narrow-linewidth EDF fiber lasers and Nonplanar Ring Laser oscillators (NPRO) by a factor of 166 and 2 respectively.
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Sundaresan, H. "The development of narrow linewidth, tunable lasers operating at 1.55#mu#m." Thesis, University of Sheffield, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390890.
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Yeo, Terence E. "Novel high precision microlithographic techniques applicable to distributed feedback laser grating manufacture." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/13625.
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Distributed feedback, DFB, lasers are a major source for long haul optical fibre based telecommunication systems. They rely on ultrahigh precision gratings to reduce mode competition within the laser cavity, thereby making single frequency operation possible. Techniques applied to DFB grating manufacture tend to be either holographic, or a direct serial write process using slow and expensive electron beam lithographic machines. An entirely new approach is proposed which compliments the accuracy of the electron beam systems with the high throughput and relatively low cost of a conventional contact mask regime. The new process relies on a group of materials which are able to retain an embossed relief upon curing with ultraviolet radiation. The main manufacturing stages of this new technique are presented including details of the embossing tool fabrication using reactive ion etching, and characterisation of material properties. It is proposed that the technique, whilst intended for DFB manufacture, could find applications in many other areas, for instance as a route to low cost replication of photomasks. In addition a new grating assessment technique, based on normal reflectance measurements, has been developed. The technique has been used to investigate hitherto unmeasured effects in electron beam lithography on a variety of substrate materials before and after semiconductor overgrowth. Details of a theoretical exercise which agrees closely with experimental results are included. The technique is non-destructive and should be of interest to all areas of microlithography and holographic imaging where it is important to have control over a wide range of process stages or where the feature size rules out the use of conventional optical microscopes.
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Nkanta, Julie Efiok. "Modelling and Characterization of Laterally-Coupled Distributed Feedback Laser and Semiconductor Optical Amplifier." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34869.
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There is an increasing need for tuneable spectrally pure semiconductor laser sources as well as broadband and polarization insensitive semiconductor optical amplifiers based on the InGaASP/InP material system, to be monolithically integrated with other active and passive components in a photonic integrated circuit. This thesis aims to contribute to finding a solution through modelling, experimental characterization and design improvements.
In this thesis we have analyzed laterally-coupled distributed feedback (LC-DFB) lasers. These lasers have the gratings etched directly out of the ridge sidewalls thus lowering the cost associated with the re-growth process required if the gratings were otherwise embedded above the active region. The performance characteristics are analyzed for the LC-DFB lasers partitioned into 1-, 2-, and 3-, electrodes with individual bias control at various operating temperatures. The laser exhibits a stable single mode emission at 1560 nm with a current tuning rate of ~14 pm/mA for a tuning of 2.25 nm. The side modes are highly suppressed with a maximum side-mode suppression ratio of 58 dB. The light-current characteristics show a minimum 40 mA threshold current, and power saturation occurring at higher injection currents. The linewidth characteristics show a minimum Lorentzian linewidth of 210 kHz under free-running and further linewidth reduction under feedback operation. The multi-electrode LC-DFB laser devices under appropriate and selective driving conditions exhibit a flat frequency modulation response from 0 to above 300 MHz. The multi-electrode configuration can thus be further exploited for certain requirements. Simulation results and design improvements are also presented.
The experimental characterization of semiconductor optical amplifier (SOA) and Fabry-Perot (FP) laser operating in the E-band are also presented. For the SOA, the linear vertical and horizontal states of polarization corresponding to the transverse electric (TE) and transverse magnetic (TM) modes were considered. For various input power and bias, performance characteristics shows a peak gain of 21 dBm at 1360 nm, gain bandwidth of 60 nm and polarization sensitivity of under 3 dB obtained for the entire wavelength range analyzed from 1340 to 1440 nm. The analysis presented in this thesis show good results with room for improvement in future designs.
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Gunning, Paul. "Distributed optical TDMA photonic switch fabric based on gain-switched distributed feedback semiconductor laser diodes and electroabsorption modulators." Thesis, University of Essex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247025.
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Thorette, Aurélien. "Synchronization dynamics of dual-mode solid-state and semiconductor DFB lasers under frequency-shifted feedback : applications to microwave photonics." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S059/document.
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Le contrôle de la différence de fréquence entre deux lasers est un défi transversal à de nombreux domaines de la photonique, que ce soit dans un but de génération hétérodyne d'un battement micro-onde de grande pureté, ou pour des expériences de métrologie ou de télécommunication. L'avancée des connaissances sur la dynamique de lasers soumis à divers couplages a permis le développement de méthodes de stabilisation basées sur l'injection optique. Nous étudions ici théoriquement et expérimentalement un mécanisme appelé réinjection décalée en fréquence (RDF), qui permet dans des situations variées de contrôler précisément la différence de fréquence entre deux lasers. Dans un premier temps, la méthode RDF est appliquée à un laser à état solide bi-polarisation bi-fréquence Nd:YAG afin de verrouiller en phase ses deux modes de polarisation orthogonaux. Le développement d'un modèle type «rate equations» en bonne adéquation avec les expériences a aussi permis de mettre en lumière un certain nombre de régimes de synchronisation partielle dits de phase bornée. De plus, nous montrons que cet état peut subsister en présence d'oscillations chaotiques de l'intensité et de la phase. Le comportement du laser sous RDF est étudié pour différentes valeurs du désaccord de fréquence, du taux d'injection, du retard éventuel, et du couplage inter-modes. Enfin, la nécessité d'inclure un couplage phase-amplitude (facteur de Henry non-nul) dans le modèle a mené au développement d'une méthode pour mesurer ce coefficient habituellement négligé dans les lasers solides. Le mécanisme de stabilisation par RDF est ensuite appliqué à un composant semiconducteur original contenant deux lasers DFB sur InP. Malgré une plus grand complexité du schéma de couplage, et la présence de retards effectifs importants, il reste possible de synchroniser en phase ces lasers. Des bandes d'accrochages liées au retard sont observées, et reproduites à l'aide d'un modèle numérique. Ce dernier permet aussi de déterminer les conditions de fonctionnement minimisant l'influence de paramètres expérimentaux non maîtrisés. Enfin, ce système, permettant de contrôler une phase micro-onde sur porteuse optique, peut être intégré dans une boucle résonante de type oscillateur opto-électronique (OEO) qui ne nécessite pas de référence externe. On réalise un oscillateur micro-onde sur porteuse optique auto-référencé, à bande latérale unique, ayant des performances encourageantes. Dans ce cadre, il semble que la plupart des techniques développées pour les OEO puissent être réinvestiesThe control of the frequency difference between two lasers is a cross-cutting challenge in many fields of photonics, either for the generation of high-purity heterodyne microwave beatnotes, or in metrology and telecommunication experiments. The advances of the comprehension of laser dynamics under various couplings has allowed to develop stabilization methods based on optical injection. We study here theoretically and experimentally a mechanism called frequency-shifted feedback (FSF), which allows to precisely control the frequency difference between two lasers in several situations.First, the FSF method is applied to a dual-frequency dual-polarization solid-state Nd:YAG laser, in order to lock the phases of its two orthogonal polarization modes. A model of rate equations is used to precisely describe the experiment, and allows to highlight partial "bounded phase" synchronization regimes. Furthermore, we show that in some cases this synchronization can subsist even with chaotic oscillations of the intensity and phase. The behavior of the laser under FSF is studied for varying values of the frequency detuning, injection rate, possible injection delay, and mode coupling in the active medium. Finally, we find that the inclusion of a phase-amplitude coupling (non-zero linewidth enhancement factor) is needed in the model to account for experimental observation. This leads to the development of an ad-hoc technique to measure the low value of this usually neglected factor in solid-laser lasers.The FSF stabilization mechanism is then applied to a custom semiconductor component embedding two DFB lasers overs InP. In spite of a more complex coupling scheme and the large effective delays into play, phase locking of the two lasers is possible. Due to the delay, locking bands appear when the detuning changes, and this behavior can be replicated using a numerical model. This model also permit to determine working conditions minimizing the influence of uncontrolled experimental optical feedback phases. Finally, as this system allows to control a microwave phase over an optical carrier, it can be integrated in a resonant loop not unlike an opto-electronic oscillator (OEO). We realized an oscillator generating a self-referenced, single sideband microwave signal over an optical carrier, with encouraging phase noise performances. In this case, it seems that most of the techniques that exist for standard OEO can be reused
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Al-Hosiny, Najm M. "Nonlinear dynamics of a distributed feedback laser subject to single and dual optical injection." Thesis, University of Essex, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434393.
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Haughey, Anne-Marie. "A distributed feedback for organic semiconductor laser platform for assessing the risk of cardiovascular disease." Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24548.
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Organic distributed feedback (DFB) lasers are a class of evanescent wave technology that can be used to measure changes in refractive index at the laser surface. These sensors are highly attractive for biosensing applications as they provide a sensitive platform for the label-free detection of a range of analytes, possibly in real-time, and they can be multiplexed for the detection of a suite of different analytes from a single test sample. The simple implementation of DFB lasers for sensing also means that they can be packaged into a compact sensing platform; this is especially true of DFB lasers incorporating an organic semiconductor as the gain layer where optical pumping may be performed with a compact source, such as a laser diode. In addition, organic semiconductor based DFB lasers have the potential for improved sensitivity relative to other organic DFB lasers (such as dye-doped) as the refractive index of organic semiconductors is generally higher, which leads to an increase in the interaction of the laser mode with the analyte binding region at the laser surface. In this thesis, the rst demonstration of an organic semiconductor (oligofluorene truxene (T3)) DFB laser for biosensing applications is described. Sensor development is focused on the ultimate aim of incorporating a T3 DFB laser into a compact and portable highthroughput sensing platform for the detection of cardiac biomarkers, Apolipoprotein B100, C-reactive protein and B-type natriuretic peptide in particular. Detection of these biomarkers is to be achieved via functionalisation of the T3 surface with oligonucleotide based probes. The structure of the T3 DFB laser is optimised experimentally and theoretically by tuning the gain layer thickness to maximise sensitivity to changes in refractive index at the laser surface, such as the binding of an analyte. The optimised laser sensor has a laser threshold of 30 µJ.cm⁻²/6 kW.cm⁻² (5 ns pulse duration) which makes optical pumping with a laser diode a possibility. The sensing potential of the DFB laser is shown via the detection of bulk solution refractive index changes and the addition of biomolecules to the laser surface, where a bulk sensitivity of 22 nm per refractive index unit is observed. The specific biosensing potential of the laser is highlighted through the functionalisation of the laser surface with biotin molecules and the subsequent detection of the complementary protein, avidin. The lowest limit of avidin detection achieved is 1µg.mL⁻¹; at this level of sensitivity, the current T3 laser is expected to be able to detect the larger and more abundant of two of the three cardiac biomarker targets, ApoB and CRP. The effects of structural changes to device sensitivity are modelled theoretically and demonstrate that detection of BNP may be achieved through the addition of a high-index cladding layer, a technique currently used for dye-doped DFB lasers. The first demonstration of a DFB laser used for reversible sensing is also presented in this thesis. Through the use of desthiobiotin, a biotin analogue, reversible avidin detection is performed. A reversible biosensor may be of particular interest for applications where a large number of repeated measurements are required, and may be prohibitive to the use of single-use, disposable sensors. Finally, functionalisation of the DFB laser with oligonucleotide probes is described. Several different techniques are explored for immobilisation of oligonucleotide probes on the T3 surface, with click chemistry and sulfhydryl linkage chemistries showing the most promise.
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Rocha, Licinio. "Microstructures électroluminescentes organiques : applications à la gestion de l'émission lumineuse." Paris 6, 2002. https://tel.archives-ouvertes.fr/tel-00126698.
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Kechaou, Khalil. "Modélisation et caractérisation de sources optiques pour les réseaux d'accès et métropolitains." Phd thesis, Télécom ParisTech, 2012. http://pastel.archives-ouvertes.fr/pastel-00998832.
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Le déploiement des réseaux optiques d'accés et métropolitains à crée un besoin incessant de débits élevés et de portées étendues. Une demande pour des sources optiques compactes, polyvalentes, de bas coût et de consommation réduite a vu le jour dans ce contexte. Le but de cette thèse consiste à étudier expérimentalement et par la simulation deux techniques pour combattre les effets de la dispersion chromatique à travers l'ingénierie du chirp de la source. La première technique concerne les lasers DFB (Distributed Feedback Laser) modulés directement. Premièrement, un modèle complet et flexible d'un laser DFB développé au cours de la thèse a été exploité pour confirmer l'étude expérimentale des effets de phases du réseau de Bragg aux facettes sur le comportement du chirp. Les résultats ont montré l'existence de deux familles de lasers définies suivant la position du mode d'émission par rapport à la bande interdite. Deuxiémement, une étude théorique et expérimentale a montré la stabilisation et le contrôle du chirp des lasers DFB via la présence d'une rétroaction optique externe bien ajustée. La deuxième technique concerne le concept de la modulation duale des lasers modulateurs intégrés (D-EML : Dual Electroabsorption Modulated Laser) exploitant l'ajustement de la dérive en fréquence résultant de la juxtaposition d'une modulation de fréquence appliquée sur le laser et une modulation d'intensité appliquée sur le modulateur. L'évaluation expérimentale et théorique des performances du D-EML a permis de prouver sa compatibilité aux hauts débits (20, 25 et 40 Gb/s) ainsi que son efficacité par rapport à la modulation simple de l'EAM (Electro-Absorption Modulator).
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Richardson, Scott. "The fabrication and lithography of conjugated polymer distributed feedback lasers and development of their applications." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/401.
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Blanchard, Romain. "Fourier optics for wavefront engineering and wavelength control of lasers." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11216.
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Since their initial demonstration in 1994, quantum cascade lasers (QCLs) have become prominent sources of mid-infrared radiation. Over the years, a large scientific and engineering effort has led to a dramatic improvement in their efficiency and power output, with continuous wave operation at room temperature and Watt-level output power now standard. However, beyond this progress, new functionalities and capabilities need to be added to this compact source to enable its integration into consumer-ready systems. Two main areas of development are particularly relevant from an application standpoint and were pursued during the course of this thesis: wavelength control and wavefront engineering of QCLs. The first research direction, wavelength control, is mainly driven by spectroscopic applications of QCLs, such as trace gas sensing, process monitoring or explosive detection. We demonstrated three different capabilities, corresponding to different potential spectroscopic measurement techniques: widely tunable single longitudinal mode lasing, simultaneous lasing on multiple well-defined longitudinal modes, and simultaneous lasing over a broad and continuous range of the spectrum. The second research direction, wavefront engineering of QCLs, i.e. the improvement of their beam quality, is relevant for applications necessitating transmission of the QCL output over a large distance, for example for remote sensing or military countermeasures. To address this issue, we developed plasmonic lenses directly integrated on the facets of QCLs. The plasmonic structures designed are analogous to antenna arrays imparting directionality to the QCLs, as well as providing means for polarization control. Finally, a research interest in plasmonics led us to design passive flat optical elements using plasmonic antennas. All these projects are tied together by the involvement of Fourier analysis as an essential design tool to predict the interaction of light with various gratings and periodic arrays of grooves and scatterers.Engineering and Applied Sciences
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Lange, Sophie Gloria [Verfasser], Klaus [Akademischer Betreuer] Petermann, Klaus [Gutachter] Petermann, Martin [Gutachter] Schell, and Markus-Christian [Gutachter] Amann. "Optical feedback effects within 1.55 μm InP-based DFB laser integrated Mach-Zehnder modulators for up to 100 GBd data transmission / Sophie Gloria Lange ; Gutachter: Klaus Petermann, Martin Schell, Markus-Christian Amann ; Betreuer: Klaus Petermann." Berlin : Technische Universität Berlin, 2019. http://d-nb.info/1185571809/34.
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Khairuzzaman, Md. "Digitally selected electronically switchable terahertz-over-fibre." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/digitally-selected-electronically-switchable-terahertzoverfibre(7003c9cb-fa46-4933-9348-b1977a446b7f).html.
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The Quantum Cascade Laser (QCL)-based terahertz-over-fibre (ToF) concept combines the strength of QCLs as ultra-wide bandwidth, high speed data sources, with the mature optical fibre technology. In this thesis, for the first time, by fusing multiple technologies, digitally selected, electronically-switchable ToF concept is experimentally demonstrated. Furthermore, the digital mode selection principle and electronic tuning mechanism provided by novel aperiodic distributed feedback (ADFB) multi-band filters are presented. For the development of electronically tunable ADFB lasers, a range of bound-to-continuum and chirped superlattice terahertz (THz) QCLs are measured across the frequency range 2.9 – 4.5 THz. The availability of these active materials allowed rapid assessments of the optimum design parameters for subsequent measurements. First, a range of photonic lattice-engineered lasers operating at 4.4 THz are characterized and key design parameters identified. Following this initial development, full electrical and spectral characterization of ADFB lasers operating at 2.9 THz are presented. The novelty of this work lies in the first-ever successful demonstration of discretely tunable QCLs, operating at six distinct THz frequencies. The ADFB technology was experimentally applied using various device geometries and gain dynamics. Toward this aim, results are presented for a Y coupled QCL architecture, showing that complex on-chip signal manipulation can be extended into the THz regime. In addition, it is demonstrated that ADFB technology provides broadband multi-channel optical filtering for the entire gain bandwidth. It is shown that discrete, purely electronic, tuning of simultaneous dual colour output can be achieved. Multi band optical filter functions derived from ADFB gratings possess highly nonlinear dispersion across the filter bandwidth and are found to modify the gain-induced, driving current-dependent continuous mode tuning. This thesis, therefore, presents a systematic experimental analysis of the dispersion engineered continuous fine-tuning in THz QCLs. In the final two chapters, the thesis presents, for the first time, transmission of tunable THz signals over standard single-mode optical fibre by up converting 2.9 THz QCL radiation via intra-cavity nonlinear mixing with an optical fibre-injected near-infrared (NIR) carrier in the 1.3 µm band. Discrete and continuous tuning technologies, as developed in chapters 3 – 5, are now successfully transferred to THz sidebands on the NIR carrier, extracted via a butt coupled single mode fibre and recorded using an optical spectrum analyzer. The major novel outcome of this thesis is the first demonstration of electronically tunable phase-matched points in a THz plasmon waveguide. The key breakthrough is the experimental confirmation of the photonic band-gap engineering of group velocity of THz signals – as both ‘fast’ and ‘slow’ switchable side bands are observed. Such novel nonlinear up-conversion of spectrally flexible THz signals may open up new possibilities for ultrafast THz telecom frameworks.
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Wienold, Martin. "Development of terahertz quantum-cascade lasers as sources for heterodyne receivers." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16560.
Full textAbstract:
Die vorliegende Arbeit beschäftigt sich mit der Entwicklung und Optimierung von Terahertz-Quantenkaskadenlasern (THz-QCLs) für die Anwendung als Lokaloszillator in THz-Heterodyndetektoren, insbesondere für die Detektion der astronomisch wichtigen Sauerstoff (OI) Linie bei 4.75 THz. Hierfür wurden zunächst unterschiedliche QCL-Heterostrukturen untersucht. Basierend auf einer Heterostruktur, welche schnelle Intersubbandübergänge über Streuung an Phononen ausnutzt, konnten QCLs mit hoher Ausgangsleistung und niedriger Betriebsspannung bei 3 THz erzielt werden. Während diese Laser auf dem Materialsystem GaAs/Al_xGa_(1-x)As mit $x=0.15$ basieren, führt die Erhöhung des Al-Anteils auf x=0.25 für ähnliche Strukturen zu sehr niedrigen Schwellstromdichten. Durch schrittweise Optimierungen gelang es, QCLs zu realisieren, die bei 4.75 THz emittieren. Mit Hilfe von lateralen Gittern erster Ordnung für die verteilte Rückkopplung (DFB) konnten Einzelmoden-Dauerstrichbetrieb mit hoher Ausgangsleistung, sowie Einzelmoden-Betrieb innerhalb des spezifizierten Frequenzbereichs bei 4.75 THz erzielt werden. Eine allgemeine Methode zur Bestimmung der DFB-Kopplungskonstanten erlaubt eine gute Beschreibung der Laser innerhalb der etablierten Theorie der gekoppelten Moden für DFB-Laser mit reflektiven Endfacetten. Oft steht das Auftreten negativer differentieller Leitfähigkeit bei höheren Feldstärken und die damit verbundenen Bildung von elektrischer Felddomänen (EFDs) im Konflikt mit einem stabilen Betrieb der THz-QCLs. Es wird gezeigt, dass stationäre EFDs mit Diskontinuitäten in der statischen Licht-Strom-Spannungskennlinie verbunden sind, während Selbstoszillationen, verursacht durch nicht-stationäre EFDs, eine zeitliche Modulation der Ausgangsleistung bewirken. Mit Hilfe einer effektiven Driftgeschwindigkeit für QCLs lassen sich viele der beobachteten Phänomene durch die nichtlinearen Transportgleichungen für schwach gekoppelte Übergitter beschreiben.This thesis presents the development and optimization of terahertz quantum-cascade lasers (THz QCLs) as sources for heterodyne receivers. A particular focus is on single-mode emitters for the heterodyne detection of the important astronomic oxygen (OI) line at 4.75 THz. Various active-region designs are investigated. High-output-power THz QCLs with low operating voltages and emission around 3 THz are obtained for an active region, which involves phonon-assisted intersubband transitions. While these QCLs are based on a GaAs/Al_xGa_(1-x)As heterostructure with x=0.15, similar heterostructures with x=0.25 allowed for very low threshold current densities. By successive modifications of the active-region design, THz QCLs have been optimized toward the desired frequency at 4.75 THz. To obtain single-mode operation, first-order lateral distributed-feedback (DFB) gratings are investigated. It shows that such gratings allow for single-mode operation in combination with high continuous-wave (cw) output powers. A general method is presented to calculate the coupling coefficients of lateral gratings. In conjunction with this method, the lasers are well described by the coupled-mode theory of DFB lasers with two reflective end facets. Single-mode operation within the specified frequency bands at 4.75 THz is demonstrated. Stable operation of THz QCLs is often in conflict with the occurrence of a negative differential resistance (NDR) regime at elevated field strengths and the formation of electric-field domains (EFDs). Stationary EFDs are shown to be related to discontinuities in the cw light-current-voltage characteristics, while non-stationary EFDs are related to current self-oscillations and cause a temporal modulation of the output power. To model such effects, the nonlinear transport equations of weakly coupled superlattices are adopted for QCLs by introducing an effective drift velocity-field relation.
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Hsu, Ying Chieh, and 許應捷. "Transient Grating toward Tunable Distributed Feedback (DFB) Optical Parametric Oscillation (OPO)." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/31516365510060825266.
Full textAbstract:
碩士國立清華大學
光電工程研究所
104
In the thesis, we have investigated on distributed feedback structure toward optical parametric oscillation. In order to fabricate a grating structure in the nonlinear gain medium such as MgO: LN, we used nano-second 355 nm UV pulse laser with interferometer technique to induce a periodical refractive index modulation (grating) structure, and this phenomenon is generated by photorefractive effect. Also, we demonstrated an optical parametric generation in MgO: LN which is used to detect the DFB structure. In our knowledge, Mg-doped LiNbO3 is better than pure congruent LiNbO3 with low noise, fast photorefractive response time, higher photorefractive sensitivity and optical damage threshold. We demonstrated a type I phase matching optical parametric generation with pump 532 nm by changing the temperature of the crystal from 200.7 to 106.5℃. The results shows a wide tuning range of signal and idler from 817.5 to 1523 nm. In order to design a tunable resonated cavity structure which means a tunable grating structure, we investigated on Indium Tin Oxide (ITO). In the experiment, when we pump a 355 nm UV with interferometer pattern, we discovered that there is a transient grating structure in the ITO by two-photon absorption. The maxima value of the refractive index change in ITO is ∆n=4.1×〖10〗^(-3). The tunable grating period in our interferometer setup is widely from 193.6 nm to 766.7 nm, which means the resonated wavelength is from 890nm to 2.5 μm. This particular transient grating result may give a chance on DFB OPO wave guide in future. Furthermore, in theoretical simulation, we combined the coupled-wave theory with DFB theory to discuss the longitudinal mode selectivity and parametric threshold gain, also we modified the simulation with considering the absorption term completely. At last, we used the present experimental results and then combined it into the theory. To understand the physics and the opportunity for application.
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Dong, Yao-Zhong, and 董耀中. "Microwave Spectral Characteristics of a Monolithic Two-Section DFB Laser under Controllable Optical Feedback." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/afw6uk.
Full textAbstract:
碩士國立交通大學
照明與能源光電研究所
105
Optical heterodyne is a common way to generate radio frequency (RF) signal by optical source. In our research, the monolithic two-section distributed feedback (DFB) laser with a distributed Bragg reflector (DBR) structure can generate a tunable RF signal by the interaction between each laser cavity. Due to the advantages of optical feedback effect on laser performance, especially the linewidth, we demonstrated a feedback controlling system to investigate the spectral characteristics of RF signal under different feedback level. Eventually, the linewidth reduced to almost half of intrinsic signal with the max controllable feedback intensity, and a narrow linewidth RF signal was detected when the both sections of our monolithic device were influenced by optical feedback. The dynamic behavior of RF signals under different feedback level was investigated. To analyze the multi-mode signal, we constructed a convolution spectrum which could be used to fit the lineshape measured by delayed self-homodyne technique. Besides, the linewidth of RF signal was changed by different current configuration and exhibited narrower near the injection locking region.
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Holguin, Lerma Jorge Alberto. "High-Speed GaN-Based Distributed-Feedback Lasers and Optoelectronics." Diss., 2020. http://hdl.handle.net/10754/665246.
Full textAbstract:
Gallium nitride (GaN) is a semiconductor material highly regarded for visible light generation since it provides the most efficient platform for compact violet, blue, and green light emitters, and in turn, high-quality and ubiquitous white lighting. Despite this fact, the potential of the GaN platform has not been fully exploited. This potential must enable the precise control in the various properties of light, realizing functions beyond the conventional. Simultaneously, the field of the telecommunications is looking for candidate technologies fit for wireless transmission in the next generations of communication. Visible light communication (VLC) may play a significant role in the future of the last mile of the network by providing both a fast internet connection and a high-quality illumination. Hence, a variety of optoelectronic platforms, including distributed-feedback (DFB) lasers, superluminescent diodes (SLDs), and multi-section lasers, can be used to exploit the full potential of GaN while offering unprecedented solutions for VLC and other applications, such as atomic clocks, high-resolution fluorescence microscopy, and on-chip nonlinear processing at visible wavelengths. This dissertation demonstrates green and sky-blue DFB lasers based on GaN, with resolution-limited single-mode emission at wavelengths around 514 nm and 480
nm, side-mode suppression ratio as large as 42.4 dB, and application to up to 10.5 Gbit/s data transmission. Preliminary observations of DFB lasers with emission close to the Fraunhofer lines are presented, offering a pathway for low-background noise applications. Blue-emitting SLDs are used to demonstrate a 3.8 Gbit/s transmitter while achieving spectral efficiency of up 118.2 (mW・nm)/(kA/cm2) in
continuous-wave operation. Visual quality is confirmed by coherence length and white light generation. Short-wavelength SLDs have the potential for higher resolution and fluorescence excitation in classical optical coherence tomography and fiber gyroscopes. The demonstration of a two-section green laser diode is presented, achieving coupled-cavity lasing at wavelengths of 514 nm based on an integrated green laser–absorber in self-colliding pulse configuration, operated in continuous-wave electrical injection. The integrated laser offer potential for mode- locked and Q-switched lasing. The integrated laser is suitable for reconfiguration where laser–modulator, laser–absorber, and laser–amplifier are proposed and investigated at green wavelengths.
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Li, Jingsi. "Distributed feedback lasers and integrated laser arrays for wavelength-division multiplexing systems." Thesis, 2014. http://hdl.handle.net/2152/30490.
Full textAbstract:
Distributed Feedback (DFB) lasers and integrated laser arrays are of great importance in Wavelength-Division Multiplexing (WDM) systems in fiber optic communication systems. High-performance, low-cost DFB lasers and laser arrays are highly desirable for applications in intra-datacenter transport and in local access networks. This dissertation is focused on the design, fabrication and achievement of high-performance, low-cost DFB Lasers and Integrated DFB Arrays for WDM Systems. It investigates the use of a novel sampled grating approach, called the equivalent phase shift method, to achieve integrated DFB laser arrays with single-mode lasing at uniformly-spaced and precisely-positioned wavelengths. First, laterally-Coupled DFB (LC-DFB) lasers with first-order sidewall gratings are realized, with gratings fabricated by optical interference lithography instead of e-beam. Then, LC-DFB lasers and LC-DFB laser arrays with sampled gratings and equivalent phase shifts are proposed, numerically analyzed and experimentally demonstrated. Each LC-DFB laser with an equivalent quarter-wave phase shift is shown to lase at the pre-specified wavelength in a single longitudinal mode, with good side-mode suppression ratio (SMSR) over a very wide range of injection currents. Integrated LC-DFB laser arrays with five uniformly-spaced wavelength channels are demonstrated, in close agreement with the design. For better performance, buried heterostructure (BH)-DFB laser and laser arrays are also demonstrated using the same sampled-grating technology. A 6-wavelenth laser array with a 300 μm cavity length and a 8-wavelength laser array with 250 μm cavity length are successively demonstrated, each showing precisely positioned lasing wavelengths, good SMSR, and uniformly good lasing characteristics under a wide range of operating currents and temperatures. Finally, it is demonstrated that the wavelength of a monolithic WDM laser array can be continuously tuned over a very wide wavelength range of nearly 40 nm. The proposed method offers a practical and cost-effective solution for the manufacture of high-performance, monolithic multi-wavelength DFB laser arrays as well as widely wavelength-tunable DFB lasers for integrated WDM systems.
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Chang, Bing Hui, and 張冰慧. "Surface-emitting photonic-crystal distributed-feedback laser for mid-infrared." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/hmzy3u.
Full textAbstract:
碩士國立交通大學
電子工程學系 電子研究所
104
Mid-infrared Surface-emitting photonic-crystal distributed-feedback lasers emitting at around 2.3m are reported in this thesis. The surface emission was obtained by using second order two-dimensional photonic crystal, formed by etched air holes in the semiconductor. The lasers were operated by optical pumping. Single mode operation at and above room temperature was achieved. Three different kinds of air hole shapes were used for the photonic crystal fabrication. The dependence of device performance on the air holes’ period geometry, etched depth and the filling factor were studied. Besides single wavelength lasers, we have also fabricated two-wavelength lasers using different periods for the etched holes along the X and the Y directions. The lasers were characterized at different temperatures. The characteristic temperature (T0) for the threshold shift and the temperature dependence of the emission wavelength were studied. As all DFB lasers, our lasers had very small temperature dependence on the wavelength. The polarization of the emitted light was also studied. For the single wavelength lasers, the polarization had no preferred orientation. But for the two wavelength lasers, two clear polarization orientations were clearly observed for the two different wavelengths. The mid-infrared surface emitting lasers are expected to be useful in many different applications, especially in environmental control such as gas sensing. In this thesis, the two wavelength surface emission at this wavelength was reported for the first time. I will provide additional flexibility for sensing applications.
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Hsieh, Ping-Feng, and 謝秉峰. "Holographic moiré phase-shifted grating for distributed feedback laser applications." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/q694c8.
Full textAbstract:
碩士國立中山大學
光電工程學系研究所
107
The major issue in the production of high speed distributed feedback (DFB) laser is its low device yield, which comes from the lasing wavelength instability and low side-mode suppression ratio (SMSR). Unstable lasing wavelength also leads to degraded device performance in high speed operation. It usually requires a quarter-wavelength phase-shifted grating structure to achieve stable single-wavelength lasing condition in DFB lasers. However, such grating structure can only be realized by expensive and time-consuming e-beam lithography. Alternatively, moiré phase-shifted gratings can be realized by low-cost laser interference lithography. It was originally applied for fiber grating applications. In this thesis we successfully realize highly uniform amplitude-moiré phase-shifted gratings over a large sample area by using our custom-made laser interference lithography system. In addition, we also demonstrate phase-moiré gratings by stacking two layers of grating with different periodicities to introduce phase misalignment between two grating layers. Finally, we apply both types of moiré gratings in DFB laser fabrication. The resulting devices achieve > 40 dB SMSR, > 10-mW output power, a threshold current of 9~12 mA, and a 3-dB bandwidth of up to 27.5Gb/s.
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"Distributed feedback dye-doped sol-gel silica lasers." 2001. http://library.cuhk.edu.hk/record=b6073321.
Full textAbstract:
Zhu Xiao Lei.Thesis (Ph.D.)--Chinese University of Hong Kong, 2001.
Includes bibliographical references (p. 116-121).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Mode of access: World Wide Web.
Abstracts in English and Chinese.
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Lu, Meng. "Label-free biosensor based upon replica-molded vertically emitting distributed feedback laser /." 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3363026.
Full textAbstract:
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009.Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3640. Adviser: Brian T. Cunningham. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.
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"Optical generation of millimeter-waves with a two section distributed feedback laser." 1999. http://library.cuhk.edu.hk/record=b5890043.
Full textAbstract:
by Ho Hing Wa.Thesis (M.Phil.)--Chinese University of Hong Kong, 1999.
Includes bibliographical references.
Abstracts in English and Chinese.
Abstract --- p.i
摘要 --- p.iii
Acknowledgment --- p.iv
Table of Contents --- p.v
Chapter 1 --- Introduction
Chapter 1.1 --- Background of optical generation of millimeter-waves --- p.1 -1
Chapter 1.2 --- Application of the two-section DFB laser on optical generation of millimeter-waves --- p.1 -4
Chapter 1.3 --- Analysis --- p.1-4
Chapter 1.4 --- Organization of Thesis --- p.1 -5
References --- p.1-6
Chapter 2 --- Techniques of Optical Generation of Millimeter-waves
Chapter 2.1 --- Direct modulation and mode-locking of lasers --- p.2-1
Chapter 2.2 --- Beating of two optical waves --- p.2-3
References --- p.2-11
Chapter 3 --- Experimental Results and Discussions
Chapter 3.1 --- Device structure and experimental setup --- p.3-1
Chapter 3.2 --- Light-Current Characteristics of the two-section laser --- p.3-3
Chapter 3.3 --- Spectral behaviours of the two-section DFB laser --- p.3-5
Chapter 3.3.1 --- Linewidth of the two-section DFB laser --- p.3-5
Chapter 3.3.2 --- Wavelength tuning of the two-section DFB laser --- p.3-5
Chapter 3.3.3 --- Biasing conditions for the dual-mode oscillations --- p.3-16
Chapter 3.4 --- Optical generation of millimeter-waves --- p.3-17
Chapter 3.4.1 --- Mechanism of beating --- p.3-17
Chapter 3.4.2 --- Generation of millimeter-waves by optical beating --- p.3-20
Chapter 3.5 --- Optical Transmission of the millimeter-waves --- p.3-22
References --- p.3-24
Chapter 4 --- Theory of DFB Laser
Chapter 4.1 --- Development of DFB laser --- p.4-1
Chapter 4.2 --- Structure of DFB laser --- p.4-2
Chapter 4.3 --- Model of one-section DFB laser --- p.4-4
Chapter 4.4 --- Analysis of two-section DFB laser --- p.4-10
Chapter 4.4.1 --- Introduction of transfer matrix method --- p.4-11
Chapter 4.4.2 --- Formulation of transfer matrix --- p.4-12
Chapter 4.4.3 --- Application of the transfer matrix --- p.4-13
References --- p.4-17
Chapter 5 --- Numerical Analysis of the Spectral Behaviours of the Two-Section DFB Laser
Chapter 5.1 --- Solving the Transcendental Equation --- p.5-1
Chapter 5.2 --- Simulation of the spectral behaviour of the two-section DFB laser --- p.5-4
Chapter 5.2.1 --- Assumptions and Approximations --- p.5-4
Chapter 5.2.2 --- Parameters --- p.5-5
Chapter 5.2.3 --- Computer Implementation --- p.5-6
Chapter 5.2.4 --- Results and Discussion --- p.5-7
References --- p.5-14
Chapter 6 --- Conclusion
Chapter 6.1 --- Summary --- p.6-1
Chapter 6.2 --- Future works --- p.6-2
Appendices
Appendix A Source code for simulation of spectral behaviours of the two-section DFB laser --- p.A-1
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"Numerical modelling of an Erbium-Ytterbium co-doped distributed feedback fiber laser." Thesis, 2015. http://hdl.handle.net/10210/13815.
Full textAbstract:
M.Phil. (Electrical and Electronic Engineering)A numerical model of an Erbium-Ytterbium co-doped distributed feedback (DFB) fiber laser is developed. The DFB fiber laser is a short length fiber laser whose feedback is distributed throughout the cavity. Its main advantage is its single longitudinal mode operation. The amplifying medium of a DFB fiber laser is a few centimetres long rare earth doped fiber. The feedback is obtained by a fibre Bragg grating printed in the core of the rare earth doped fiber. This type of laser emits naturally in two longitudinal modes. To obtain the single longitudinal mode operation, a π phase shift is introduced in the middle of the grating. Erbium doped DFB fiber lasers present the advantage of emitting single frequency light in the 1550 nm region where telecommunication fibers present the minimum loss. However due to the relatively short length of the gain medium, the number of available Erbium ions is small; as a result pump power absorption is low and the efficiency of the fiber laser is strongly reduced. The straightforward solution to this problem could be increasing the concentration of Erbium ions. This solution however has the disadvantage of increasing the Erbium ions interactions, thus leading to detrimental effect like cooperative upconversion and excited state absorption, which in term reduce considerably the laser efficiency. The best solution is to use Ytterbium ions as sensitizers along with Erbium ions to enhance the pump absorption, hence the efficiency of the laser. A model of the DFB fiber laser is an indispensable tool for its design, because it allows one to predict characteristic behaviour that would be both difficult and costly to deduce in laboratory conditions. The model developed in this project is based on rate equations of the Er3+-Yb3+ gain medium and coupled mode equations describing the laser field propagation in the fibre Bragg grating structure. The equations are solved using a quasi-analytical iterative method along with transfer matrix method with appropriate boundary conditions. The quasianalytical method used in this thesis is more robust than numerical solutions because it does not require providing an initial guess on the solution. Furthermore this method is hundreds time faster than the exact numerical solution while giving almost similar results.
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Wu, Chi-Chang, and 吳奇璋. "Fabrication of Integrated Distributed-Feedback Laser with Traveling-Wave Electro-Absorption Modulator." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/97647015496727869189.
Full textAbstract:
碩士國立臺灣科技大學
光電工程研究所
98
The goal of this thesis is to design and realize high-speed electroabsorption-modulator lasers (EMLs). The material for gain and modulation region is InGaAsP-based multiple quantum wells (MQWs) with the same composition. Quantum well intermixing technique is used to blue-shift the MQWs in the modulation region. Laser emission is designed at 1550 nm of wavelength. For high-speed modulation, wavelength difference between gain and modulation region needs to be about 110 nm. Besides, traveling-wave coplanar structure is utilized to overcome the RC-limited bandwidth, thus achieving a higher modulation speed. PMGI is also used to further reduce the parasitics in this 4 um ridge-waveguide EMLs. We have designed and tested the whole process procedures and conditions for realizing this type of device, including lithography conditions, PMGI deposition, and self-alignment. For device characterization, the wavelength difference between the gain and modulation region is obtained from the photo-luminescent spectra and electro-luminescent spectra to be about 97.88 nm and 65 nm, respectively. The emission wavelength bands of the controlled lasers and modulator samples are around 1550 nm and 1485 nm with a contact resistance of around 27 Ω and 34 Ω. The absorption peak wavelength of the modulator is about 1500 nm or lower. The electrical isolation between the gain and modulation region is achieved by etching 50 um wide and 1.4 um deep trenches between the two section. The electrical resistance is measured to be around 19 kΩ.
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Lin, Li-Fan, and 林立凡. "Study of GaN-based Two-Dimensional Surface-Emitting Photonic Crystal Distributed-Feedback Laser." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/06931231337490490359.
Full textAbstract:
碩士國立交通大學
光電工程系所
95
In this thesis, we study the fabrication and characteristics of GaN-based two-dimensional surface-emitting photonic crystal distributed-feedback (2D SEPC DFB) laser. We also simulated the band diagram of the PC structure to realize the lasing mechanism by using plane-wave expansion (PWE) method. We fabricated these devices with different lattice constant (from 190nm to 300nm) by using electron-beam lithography (EBL). The laser action of photonic crystal devices was achieved under the optical pumping at room temperature. The clear threshold characteristic was observed at different devices (a=190-300nm). All these devices show a similar threshold pumping energy densities to be about 3.5mJ/cm2. The GaN-based 2D SEPC DFB laser emits violet wavelength (from 397nm to 425nm) with a linewidth of about 1.1Å. In addition, the degree of polarization (53%)、divergence angel (<10∘) and emission image of the laser was also measured. In emission image of the laser, we obtain a stimulated emission of GaN-based 2D SEPC DFB laser over a large area. All emission light normal to the sample surface is collected into a spectrometer/CCD, and the lasing spectrum shows just one lasing mode in the whole lasing area. So, it is clear, the single mode GaN-based 2D SEPC DFB laser with large lasing area was demonstrated. Finally, we compare experiment results with simulation results. We are able to classify the normalized frequency into few groups. Different groups of the normalized frequency occur at different points of Brillouin-zone boundary, Γ、M、K points. All points of normalized frequency can exactly correspond to points of Brillouin-zone boundary because the Bragg condition only satisfies at these points.
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Nesnidal, Michael P. "Novel spatial-mode selection using distributed feedback gratings in single-mode resonant antiguided diode laser arrays." 1998. http://catalog.hathitrust.org/api/volumes/oclc/40282621.html.
Full textAbstract:
Thesis (Ph. D.)--University of Wisconsin--Madison, 1998.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 147-152).
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Chen, Sing-Yu, and 陳星宇. "Design and Fabrication of Distributed-Feedback Laser and Electro-Absorption Modulator by Quantum-Well Intermixing Technique." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/98128391610536634717.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
96
We integrate DFB laser and electroabsorption modulator by using the quantum well intermixing(QWI) technique for application in high speed transmission system. The active region is InGaAsP based quantum well structure. We utilize the impurity-induced inter-diffusion technique to change the bandgap of the active region and analyze the diffusion effect for different annealing conditions. We simulated the change of bandgap in the active region after appling the QWI technique. We observe the trend of wave-function change in the parabolic well. The active region material characteristics are analyzed to optimize the quantum well width. We measure the photoluminescent spectrum after the annealing at 700℃and 750℃, respectively. The shift of peak wavelength up to 80 nm is observed. After this investigation, we choose 65 nm of blue shift from the QWI to realize the electron-absorption modulated laser. The fabrication procedures and preliminary experimental results are demonstrated.
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Hsiao, Yu-Chao, and 蕭宇超. "Radio-over-Fiber Transport Systems Based On Distributed Feedback Laser Diode With Main and -1 Side Modes Injection-locked Technique." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/8ffh98.
Full textAbstract:
碩士國立臺北科技大學
光電工程系研究所
97
In this thesis, we study various structures of optical fiber communication transport systems. The proposed transmission systems which are demonstrated include transport systems of analog and digital as well as transport systems of Radio-over-Fiber (ROF) and Full-duplex Radio-over-Fiber. The different schemes of transmission are engineered according to different techniques such as injection-locked technique, direct modulation, external modulation, and single sideband modulation in order to enhance side-mode suppression ratio (SMSR) and reduce dispersion. Therefore, the overall performance and configuration of transmission are extremely improved First, employing mutually injection-locked Fabry-Perot (FP) Laser Diodes which possesses superior cost-effective benefits and multi-modes characteristics can achieve the flat and multi-modes spectrum. Accordingly, a broadband light source is obtained. Besides, it reveals an outstanding alternative with advantages in simplicity and cost instead of using expensive external modulators and sophisticated optical carrier suppression technique. Second, employing only one optical sideband modulation technique greatly reduced the dispersion because it effectively diminished the linewidth so as to decrease radio frequency (RF) fading effect. Furthermore, it is convenient and beneficial for the systems and base stations to simplify and upgrade architectures through wavelength division multiplexing (WDM) and optical add-drop multiplexers (OADM) techniques. Third, employing the -1 side mode of distributed feedback (DFB) laser diode injection-locked technique and optoelectronic feedback technique extremely raises SMSR and optical power according to the extension of previous studies and researches. Consequently, the baseband (622Mbps) signal and the RF (622Mbps/10GHz) signal are successfully transmitted simultaneously over an-80 km single mode fiber (SMF). Hence, it integrates the transport systems of fiber-to-the-home (FTTH) and ROF. Finally, employing main and -1 side modes of DFB LD injection-locked technique according to the extension of previous studies and researches not only significantly increases the resonance frequency of the slave laser, but also prominently enhances SMSR. Moreover, any chosen side modes can be transmission light sources which provide several light sources to transmit. In addition, the system based on these techniques in direct modulation can transmit over a-40km SMF for the downstream and an-80km SMF for the upstream without any other light source in base stations. Good performances of bit error rate (BER) was achieved and improved. Therefore, a state-of-the-art lightwave centralized network is realized.
41
Lin, Shih-Chang, and 林世昌. "Design of Device Structure and Fabrication Procedures for Integrated Distributed-Feedback Laser with Electro-Absorption Modulator on Semi-Insulating Substrate." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/72921175444834372106.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
97
The quantum well intermixing（QWI）technique is used to fabricate the integrated device that combines a distributed feedback laser（DFB） and an electro-absorption modulator（EAM） on semi-insulating substrate for very high speed fiber communication system（>40 Gbits/s）. The active layers of quantum wells are made of InGaAsP materials, and the lasing wavelength is designed to be 1550 nm. In the device structure, the traveling-wave（TW）structure is better than the lumped structure due to its lower parasitic capacitance, which leads to a high modulation bandwidth. We choose the traveling-wave coplanar structure to realize the DFB/EAM integrated devices. To obtain lower transmission loss （< 10 dB） and higher extinction ratio（>15 dB）, the EAM absorption spectrum is analyzed, and the optimal blue shift value is approximately 52 to 64 nm. In this range of blue shift wavelength, a high extinction ratio（>18dB）can be obtained for 1.2 V driving voltage. The maximum blue shift value can reach to 98 nm for the QWI annealing test. For comparisons with the QWI device, the identical active layers and used for realizing the integrated DFB/EAM laser, the key concept of this technique is to locate the lasing wavelength of the DFB at the absorption edge of EAM. Therefore, we should make sure that the laser could lase at the wavelength of absorption edge of the EAM. From the simulation results, the lasing wavelength may exceed 1600 nm.
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Kai-YuYu and 游凱宇. "Investigations on tunabilities of pretilt angle and distributed feedback laser based on liquid crystal cells incorporating with micro- and nano-grooves of polymer." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/91329408023067214457.
Full textAbstract:
博士國立成功大學
光電科學與工程學系
102
This thesis, entitled “Investigations on the tunability of pretilt angle and distributed feedback laser based on liquid crystal cells incorporated with micro- and nano-grooves of polymer,” examines the tunability of liquid crystal (LC)-based optical devices with a grooved structure. The following two topics are discussed. (1) Controllable pretilt angle of LCs with the formation of microgrooves. This work investigates the controllability of the pretilt angle of LCs in a cell with an initial vertical alignment through microgrooves induced by the holographic fast-writing method. By changing the writing time or intensity of the pumped beam, the microgrooves with various surface modulations can form and provide distinct planar anchoring strength for the LCs. The pretilt angle of the LCs can be controlled from 18.3° to 89°. The writing time of the microgrooves takes less than 25 s, which is a two-fold reduction in the time taken in previous investigations using other photoalignment methods. (2) Thermally tunable LC distributed feedback laser based on a polymer grating with nanogrooves fabricated by nanoimprint lithography (NIL). This work demonstrates a thermally tunable dye-doped liquid crystal (DDLC) distributed feedback (DFB) laser based on a polymer grating. The surface emitting the DDLC DFB laser is supported by the second-order Bragg grating with nanogrooves with periodicity of 360 nm and pre-fabricated by UV NIL. The lasing wavelength of the DFB laser can be tuned from 625.1 nm to 606.35 nm if the temperature increases from 10 °C to 50 °C. The tunability of the laser is attributable to the temperature-sensitive feature in the effective refractive index of the LCs.