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Dissertations / Theses on the topic 'Laser diodes'
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1
Lau, Fat Kit. "Tapered waveguide laser diodes." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611648.
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Cappuccio, Joseph C. "Semiconductor laser diodes and the design of a D.C. powered laser diode drive unit/." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23114.
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This thesis addresses the design, development and operational analysis of a D.C. powered semiconductor laser diode drive unit. A laser diode requires an extremely stable power supply since a picosecond spike of current or power supply switching transient could result in permanent damage. The design offers stability and various features for operational protection of the laser diode. The ability to intensity modulate (analog) and pulse modulate (digital) the laser diode output for data transmission was a major design consideration. Laser optical power is controlled via a closed loop system using a monitor photodiode. Laser diode temperature stabilization is accomplished with the use of a thermoelectric cooler. Laboratory and remote applications were considered in the design of this unit. (rh)
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Schimmel, Guillaume. "Combinaison cohérente de diodes laser de puissance." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLO018/document.
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La capacité des sources laser à concentrer une quantité d’énergie énorme intéresse beaucoup le secteur industriel pour l’usinage et la structuration de la matière. Il faut pour cela rassembler une forte puissance optique sur une surface infime: on parle alors de luminance. La combinaison cohérente permet de répondre à la problématique de l’augmentation de la luminance d’un système laser. Dans le cadre du projet européen BRIDLE, ces travaux sont focalisés sur la combinaison cohérente de lasers à semi-conducteur. Ce type de combinaison nécessite un accord de phase stable entre les différents émetteurs. Plusieurs techniques permettent cette mise en phase; nous étudions en particulier les techniques d’amplification en parallèle ainsi que l’utilisation d’une cavité externe commune. L’originalité se situe dans le développement d’une architecture nouvelle, pensée pour optimiser l’extraction de puissance. La technique consiste à utiliser une cavité étendue commune aux émetteurs à combiner pour leur mise en phase, placée sur leur face arrière. Tout en fournissant un fort retour optique arrière nécessaire à la mise en phase, l’extraction de puissance est maximisée sur la face avant où les faisceaux sont par la suite combinés extracavité. Ce document démontre la bonne adéquation de cette architecture avec les meilleures diodes laser en termes de luminance : les émetteurs à section évasée. L’étude est étendue à une barrette de diodes par l’utilisation d’éléments diffractifs optique permettant la séparation et la combinaison des faisceauxScaling up the brightness of laser diodes is a major research objective in the laser community. The coherent beam of several emitters is the most efficient technique to increase the brightness by constructive interference. An efficient combination can only be achieved in an arrangement that forces the required phase relation between the emitters. Different approaches are investigated: either active phase-locking of amplifiers seeded by a single-frequency laser split into N beams and amplified in parallel, or passive selforganization of emitters in a common laser cavity. We investigate a new coherent combining architecture using a common extended cavity on the back side of diode lasers for phase locking. As a result, the efficiency of the phase-locked laser cavity is increased as compared to standard front-side configurations. Moreover, such an extended cavity placed on the rear-side provides the strong optical feedback required for phase-locked operation. This configuration is demonstrated with high-brightness tapered devices, highlighting the capability of such setup for high power operation. This architecture is then extended to diode laser arrays by the use of diffractive optical elements
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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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Huang, G. "Wavelength stabilisation in laser diodes." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604711.
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This thesis discusses the wavelength stabilisation of semiconductor lasers for WDM applications. The motivation is to explore the potential of a novel athermal WDM laser with much less wavelength drift than conventional lasers, and without the traditional external temperature compensation units. The study is mainly theoretical, but some experimental work is included. Based on the Cambridge time domain model, intensive simulation has been done to investigate the design space of DBR lasers. Although the structure of the initial prototype DBR model is simple, the simulation output results are rather complex. All the main parameters such as grating length, grating coupling strength, total laser cavity length and waveguide scattering loss are varied. Results obtained agree with current measurements on DBR lasers, and support dimensions and structures derived empirically. Based upon the above results, simulation work then goes further towards the athermal WDM laser idea which employs negative temperature coefficient material to physically compensate the frequency variation with temperature. A polymer widely used in optical waveguides is one candidate. Having reviewed temperature dependent parameters in semiconductor lasers, we incorporated these into the Cambridge Time Domain model. It predicts a wavelength shift of about 0.75 nm over a 100o C range at wavelength of 1500 nm where about 9nm would be expected from a normal DFB laser. It also reveals other complex and interesting behaviour, which is likely to give several useful insights into the behaviour of tuneable and other forms of DBR and BFB lasers. An experiment to verify the athermal effect of a polymer has been done. Focussed ion beam etch was employed to form a deep grating in near-conventional FP laser, and the grating voids were filled with the polymer. Lasing action with good wavelength stability was observed, though the particular structure employed is probably not capable of single mode operation over a wide temperature range.
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Spencer, Peter David. "Quantum dot bilayer laser diodes." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/1413.
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Optical communication was developed to allow high-speed and long-distance data transmission and is currently a £6bn market. This has also led to the adoption of optical technologies in other areas including the CD, DVD and medical imaging systems. Standardisation of components means that these systems require light sources that operate near the 1310 and 1550 nm telecommunications windows but existing lasers here are expensive due to their high temperature sensitivity. The exploitation of quantum con¯nement has led to the development of \quan- tum dot" (QD) laser material because of predictions of huge gains in performance. Emission wavelengths of InAs/GaAs QD lasers have been extended to the telecom- munications window near 1300 nm by various growth technologies and the first commercial devices have recently been brought to the market. However, progress to longer wavelengths has been stalled for several years as well as the speed and tem- perature sensitivity of these devices falling short of the predictions; partly because QDs are grown by self-assembly resulting in a random distribution of sizes, compo- sitions and strain-states, leading to inhomogeneous broadening which is a departure from the ideal \atom-like" system. This work details the growth, design and development of QD bilayer laser devices, which o®er a unique approach to fixing these shortcomings. When two QD layers are grown close together; the first layer provides a template that allows larger, more uniform QDs to be grown in the second layer, giving greater uniformity and deeper confinement. This has the potential to increase the efficiency and to achieve emission wavelengths out towards the more-commonly used telecommunications window at 1550 nm directly on GaAs substrates. Multiple bilayer laser diodes with inhomge- neous broadening of less than 30meV, lasing at up to 1430 nm and room-temperature photoluminescence at 1515 nm are shown. Despite the vastly reduced inhomogeneous broadening of QD bilayers, it is still found to be a relevant factor due to the change from de-localised geometries of quantum wells to an ensemble of separate QDs. It will be shown that understanding this is essential for describing the observed optical and electrical behaviour of the laser diodes.
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Meyers, Mark. "Laser diodes incorporating diffractive features /." Online version of thesis, 1990. http://hdl.handle.net/1850/11233.
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Lochner, Zachary Meyer. "Green light emitting diodes and laser diodes grown by metalorganic chemical vapor deposition." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33827.
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This thesis describes the development of III-Nitride materials for light emitting applications. The goals of this research were to create and optimize a green light emitting diode (LED) and laser diode (LD). Metalorganic chemical vapor deposition (MOCVD) was the technique used to grow the epitaxial structures for these devices.
The active regions of III-Nitride based LEDs are composed of InₓGa₁₋ₓN, the bandgap of which can be tuned to attain the desired wavelength depending on the percent composition of Indium. An issue with this design is that the optimal growth temperature of InGaN is lower than that of GaN, making the growth temperature of the top p-layers critical to the device performance. Thus, an InGaN:Mg layer was used as the hole injection and p-contact layers for a green led, which can be grown at a lower temperature than GaN:Mg in order to maintain the integrity of the active region. However, the use of InGaN comes with its own set of drawbacks, specifically the formation of V-defects. Several methods were investigated to suppress these defects such as graded p-layers, short period supper lattices, and native GaN substrates. As a result, LEDs emitting at ~532 nm were realized.
The epitaxial structure for a III-Nitride LD is more complicated than that of an LED, and so it faces many of the same technical challenges and then some. Strain engineering and defect reduction were the primary focuses of optimization in this study. Superlattice based cladding layers, native GaN substrates, InGaN waveguides, and doping optimization were all utilized to lower the probability of defect formation. This thesis reports on the realization of a 454 nm LD, with higher wavelength devices to follow the same developmental path.
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Lee, Junho. "Semiconductor diode laser with saturable absorber (S-laser)." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0004277.
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Nyamuda, Gibson Peter. "Design and development of an external cavity diode laser for laser cooling and spectroscopy applications." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1146.
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Nowell, Mark Charles. "Push-pull directly modulated laser diodes." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339501.
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Gärtner, Christian. "Organic laser diodes modelling and simulation." Karlsruhe Univ.-Verl. Karlsruhe, 2008. http://d-nb.info/993660703/04.
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Marcenac, Dominique David. "Fundamentals of laser modelling." Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/251657.
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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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Wykes, James G. "Numerical models for high power laser diodes." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420361.
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Phillips, Amyas Edward Wykes. "Passive wavelength athermalisation of semiconductor laser diodes." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615225.
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Demir, Abdullah. "New laser technologies analysis of quantum dot and lithographic laser diodes." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4618.
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Lithographic VCSELs ability to control size lithographically in a strain-free, high efficiency device is a major milestone in VCSEL technology.; The first part of this dissertation presents a comprehensive study of quantum dot (QD) lasers threshold characteristics. The threshold temperature dependence of a QD laser diode is studied in different limits of p-doping, hole level spacing and inhomogeneous broadening. Theoretical analysis shows that the threshold current of a QD laser in the limit of uniform QDs is not temperature independent and actually more temperature sensitive than the quantum well laser. The results also explain the experimental trends of negative characteristic temperature observed in QD lasers and clarify how the carrier distribution mechanisms inside and among the QDs affect the threshold temperature dependence of a QD laser diode. The second part is on the experimental demonstration of lithographic lasers. Today's vertical-cavity surface-emitting lasers (VCSELs) based on oxide-aperture suffer from serious problems such as heat dissipation, internal strain, reliability, uniformity and size scaling. The lithographic laser provides solutions to all these problems. The transverse mode and cavity are defined using only lithography and epitaxial crystal growth providing simultaneous mode- and current-confinement. Eliminating the oxide aperture is shown to reduce the thermal resistance of the device and leading to increased power density in smaller lasers. When it is combined with better mode matching to gain for smaller devices, high output power density of 58 kW/cm?? is possible for a 3micrometers] VCSEL with threshold current of 260 microamperes]. These VCSELs also have grating-free single-mode single-polarization emission. The demonstration of lithographic laser diodes with good scaling properties is therefore an important step toward producing ultra-small size laser diodes with high output power density, high speed, high manufacturability and high reliability.ID: 029094461; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 62-66).
Ph.D.
Doctorate
Optics and Photonics
18
Sidorin, Yakov Sergeevich 1966. "Laser diode-to-singlemode fiber butt-coupling and extremely-short-external-cavity laser diodes: Analysis, realization and applications." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282663.
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The butt-coupling of a Fabry-Perot semiconductor laser diode and a singlemode optical fiber was realized and characterized in the near field. A novel butt-coupling model was developed and found very effective in describing all physical phenomena that occur when the butt-coupling parameters are varied over a wide range. The strong external optical feedback to the laser diode cavity that is present at extremely-short separations between the laser diode and the fiber is advantageously used to realize an extremely-short external cavity laser diode. By varying the length of the external cavity, the operational characteristics of this external cavity laser diode are controlled in a predictable and repeatable manner; a wavelength tunable laser diode source based on this effect was developed and analyzed. Another realization of an extremely short external cavity tunable laser diode, based on a closely spaced external filter with variable characteristics, was demonstrated. A potential application of the butt-coupling technique for light collection in an optical recording head is discussed. The work presented here is a research tool that can be used to facilitate the design of extremely-short external cavity laser diodes, which in many ways are technologically novel.
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Paboeuf, David. "Combinaison cohérente de diodes laser de luminance élevée en cavité externe." Paris 11, 2009. http://www.theses.fr/2009PA112161.
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La demande en constante progression de sources laser compactes et efficaces conduit à rechercher des architectures nouvelles pour accroître la puissance des diodes laser. La solution la plus prometteuse consiste à utiliser plusieurs lasers identiques de puissance modérée en parallèle. Pour conserver la qualité spatiale du faisceau, il est nécessaire d’induire une relation de phase constante entre les lasers. Nous présentons une étude théorique et expérimentale de la mise en phase passive d’une barrette de diodes laser de puissance. Pour cela, nous exploitons les propriétés de filtrage angulaire et spectral des réseaux de Bragg volumiques dans une cavité externe. Deux solutions ont été étudiées : la première exploite l’effet d’auto-imagerie Talbot et la seconde effectue un filtrage sélectif des composantes angulaires de l’émission de la barrette. Un modèle permettant de déterminer le comportement modal de chacune de ces cavités a été réalisé. Dans le cas de la cavité Talbot, en collaboration avec l’université de Nottingham, la cavité a également été modélisée en prenant en compte les propriétés internes des diodes laser. Expérimentalement, plusieurs architectures adaptées à des géométries de barrettes différentes ont été étudiées, qui ont toutes donné lieu à une émission cohérente. Nous montrons que l’utilisation d’un réseau de Bragg volumique intra-cavité permet à la fois d’améliorer la cohérence entre les lasers et de stabiliser le spectre d’émission. Enfin, nous présentons une solution originale utilisant des filtres de phase permettant de convertir le faisceau multilobe provenant de la cavité laser en un faisceau de profil gaussienThe constant and growing demand for compact and efficient laser sources leads to explore new architectures aiming at increasing the he output powers of laser diodes. The most promising solution consists in utilizing several moderate-power identical lasers in parallel. It is then necessary to induce a constant phase relationship between the lasers to maintain the spatial beam quality. We present a theoretical and experimental study of the passive phase locking of an array of high-power diode lasers. We take benefit of the angular and spectral filtering properties of volume Bragg gratings in an external cavity. Two solutions have been considered : the first one uses the self-imaging Talbot effect and the second one consists in a selective angular filtering of the array emission. A theoretical model aiming at determining the modal behaviour of those two cavities has been realized. Moreover, concerning the Talbot cavity, in collaboration with the university of Nottingham, a cavity model taking into account the internal properties of the diode lasers has also been used. Experimentally, several cavity setups adapted to different array geometries have been investigated. Each of them achieved a coherent emission. We show that the use of volume Bragg gratings inside the cavity improve both the coherence and the spectrum of the lasers. Finally, we present an original solution using phase filters to convert the multilobed beam from the laser cavity into a Gaussian beam profile
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MORAES, MARIANA P. de. "Fluxometria laser doppler da polpa dental apos o clareamento com laser de diodo." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11513.
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Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia)
IPEN/D-MPLO
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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MATOS, PAULO S. F. de. "Obtencao de oscilacao em frequencia unica em lasers de estado solido bombeados por diodo-laser." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10853.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Del, Vecchio Pamela. "Étude de la dégradation et analyse de défaillance de diodes laser de puissance spatialement monomodes émettant à 980nm." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0140.
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Cette étude adresse une technologie de diodes laser à semi-conducteur InGaAs/AlGaAs/GaAs émettant à 980 nm en configuration puce nue (CSE-Composant Sur Embase) utilisées pour le pompage optique dans les amplificateurs à fibre dopée Er3+. Il s'agit de composants possédant un tel niveau de maturité technologique que l’évolution des paramètres observés au cours du temps ne présente plus de variations suffisamment significatives pour pouvoir dégager des conclusions exhaustives en termes de fiabilité. La recherche de méthodes alternatives et/ou complémentaires aux méthodes dites « classiques » visant à la compréhension des mécanismes de défaillance et l’identification des signatures indiquant une possible dégradation future des diodes laser, relève aujourd’hui un défi stratégique pour les composants actuels. Dans ce contexte, cette étude propose un ensemble de techniques basées sur la discrimination du fonctionnement des diodes en régime direct et en particulier en régime inverse par spectroscopie électrique. La corrélation des différentes mesures en régime inverse, très peu étudié dans la caractérisation des diodes laser, peut mettre en évidence des comportements atypiques qui révèlent la présence de défauts ponctuels résiduels dans le volume d’une diode car les courants observés sont très faibles. Le régime inverse permet d'offrir des perspectives intéressantes en considérant que ce régime reste de nos jours quasiment inexploré pour les composants optoélectroniques émissifs tels que les diodes laserThis study addresses InGaAs / AlGaAs / GaAs laser diode emitting at 980 nm in bare chip configuration (COS-Component on Submount) for optical pumping in Er3+ doped fiber amplifiers. These devices have a level of technological maturity that the changes in the parameters observed during aging do not present sufficiently significant variations in order to obtain exhaustive conclusions in terms of reliability. Searching for alternative and/or complementary methods to the so-called « classical » methods aimed to understanding the failure mechanisms and the identification of signatures indicating possible future degradation of the laser diodes, represents today a strategic challenge for the current components. In this context, this study suggests a set of techniques based on the discrimination of the operation mode of the diodes in direct bias and in particular in reverse bias by electrical spectroscopy. The correlation of the different measurements in reverse bias, not more studied in the characterization of laser diodes, can reveal atypical behaviors highlighting presence of residual point defects in the volume of a diode because the currents observed are very weak. The reverse bias makes it possible to offer interesting perspectives considering that, this operation mode remains today almost unexplored for optoelectronic emitting devices such as laser diodes
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May, Johanna Friederike. "Vertical Cavity Surface Emitting Laser diodes as laser sources in optical tweezers." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-60195.
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Barrow, David Antony. "Generation and detection of short optical pulses." Thesis, University of Glasgow, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360226.
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Faure, Herlet Nathalie. "Nouveaux matériaux laser dopés néodyme adaptés au pompage par diodes." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10148.
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La recherche de nouveaux materiaux laser dopes neodyme particulierement bien adaptes au pompage par diode s'est effectuee en plusieurs etapes. Tout d'abord, les caracteristiques physiques et spectroscopiques des materiaux potentiellement interessants pour le pompage par diodes ont ete definies: large bande d'absorption vers 800nm et fluorescence intense a 1060nm. Pour des applications microlaser, l'absorption doit de plus etre intense et la bande de fluorescence, etroite. Enfin les matrices doivent presenter une fusion congruente et une cristallogenese relativement aisee. Apres une etude bibliographique sur les materiaux laser elabores depuis les annees 1970, 75 candidats susceptibles de reunir les criteres definis precedemment ont ete retenus. Les etapes de preparation sous forme polycristalline, puis sous forme de monocristaux par tirage a l'aide des techniques de fusion de zone laser et czochalski ont alors permis d'effectuer une selection: seules 21 matrices dopees neodyme ont pu etre obtenues sous forme monocristalline et ont alors fait l'objet d'une caracterisation spectroscopique et laser. La position et la largeur des bandes d'absorption vers 800nm, et de fluorescence vers 1060nm, ont ete plus particulierement etudiees. Les sections efficaces d'absorption et d'emission, ainsi que la duree de vie du niveau emetteur laser du neodyme ont egalement ete mesurees. A l'issue de la caracterisation laser en pompage longitudinal par diode (mesure de seuils et de rendements laser), les scheelites cawo#4, nagd(wo#4)#2, l'orthosilicate y#2sio#5 et les fluoroapatites sr#5(po#4)#3f et ca#5(po#4)#3f semblent les matrices les mieux adaptees au pompage par diode
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Benjamin, Simon. "Cristal composite SLAB pompé latéralement par diodes laser /." [S.l.] : [s.n.], 2003. http://library.epfl.ch/theses/?nr=2871.
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Choi, Woo-Young. "MBE-grown long wavelength InGaAlAs/InP laser diodes." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34061.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 107-116).
by Woo-Young Choi.
Ph.D.
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Grudzien, Thomas. "Commutation optique par bistables optiques et diodes laser." Paris 7, 1999. http://www.theses.fr/1999PA077265.
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La disponobilité commerciale des lasers semiconducteurs à émission par la surface (VCSELs) permet à priori la conception de systèmes de traitement parallèle optique de l'information. Cette thèse présente une démostration de commutation optique de paquets réalisée grâce a des cavités Fabry Perot non linéaires, les bistables optiques, et grâce à des lasers semiconducteurs. Ce démonstrateur constitue un routeur optique simplifié : il permet de commuter un paquet depuis une voie d'entrée vers une voie de sortie parmi plusieurs. Après un rappel des travaux sur lesquels cette thèse s'appuie, les contraintes optiques et mécaniques auxquelles le démontrateur doit répondre sont présentées et un schéma fonctionnel du démonstrateur est présente. Les VCSELs sont caractérisés en longueur d'onde, modes transverses, puissance et polarisation afin de s'assurer que leurs caractéristiques sont compatibles avec celles des bistables. Il s'est avéré que ces VCSELs n'étaient pas assez monochromatiques, une étude numérique a permis de prévoir l'influence du caractère multimode transverse sur la réponse du bistable et une alternative aux VCSELs a du être envisagée afin de mener la démonstration à terme.
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Morton, Paul A. "The dynamics of directly modulated semiconductor laser diodes." Thesis, University of Bath, 1988. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382591.
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CAMARGO, FABIOLA de A. "Laser de Nd:YVOsub(4) bombeado transversalmente em configuração com ângulo rasante interno." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11406.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:03/10164-9
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Kim, Taek. "Developments in gallium nitride vertical cavity surface emitting laser technology." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366793.
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Monflier, Richard. "Etude des défauts induits par recuit laser excimère dans le silicium." Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30067.
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La micro-électronique est un domaine exigeant, en constante évolution, motivé par le secteur applicatif et les besoins des utilisateurs. La réalisation de jonctions ultra-minces et fortement dopées est un enjeu majeur pour la poursuite de son évolution, et notamment pour son composant de base, le transistor MOS. Dans ce contexte, de nouvelles techniques de dopage permettant d'obtenir des jonctions ultra-minces ont été développées. Le recuit par laser nanoseconde (LTA) en mode " melt " est une de ces techniques. En effet, il permet une très forte activation locale (en surface et en profondeur) et une distribution uniforme des dopants. Ce procédé utilisé en laboratoire depuis les années 1980 dans la fabrication des cellules solaires offre également de nouvelles possibilités technologiques comme le développement d'architectures 3D. Néanmoins, des dégradations électriques de paramètres sensibles aux défauts tels que la mobilité et le courant inverse d'un transistor MOS ou la durée de vie des porteurs dans le cas de cellule photovoltaïque ont été observées. Dans ce contexte, cette thèse propose une étude rigoureuse des défauts générés par recuit laser en deux volets. Le premier volet traite de l'impact du recuit laser sur les propriétés physiques du silicium et repose essentiellement sur des caractérisations approfondies par spectroscopie infrarouge et photoluminescence d'échantillons silicium non intentionnellement dopés soumis à diverses conditions de recuits par impulsions laser à excimère. L'étude met en évidence la formation de défauts suite au procédé de recuit laser. Leur identification a permis d'affirmer l'introduction d'impuretés d'oxygène et de carbone durant le recuit. A partir de cette identification, le suivi en profondeur par spectroscopie de masse à ionisation secondaire de chacune des impuretés a été effectué révélant une augmentation de la concentration et de la diffusion des impuretés avec l'augmentation de la densité d'énergie du laser et/ou du nombre de tirs. A haute énergie laser, les profils de concentration d'oxygène montrent la présence d'un pic immobile (en concordance avec la solubilité limite de l'oxygène dans le silicium liquide) associé à des cavités de silicium observées par microscopie électronique en transmission (MET). L'origine de ces impuretés est discutée ; la caractérisation de véhicules tests dédiés a permis de définir l'oxyde natif comme étant leurs sources. Le second volet permet de répondre au second objectif qui consiste à évaluer l'impact du recuit laser sur les propriétés électriques de composants à base de silicium et s'appuie sur la caractérisation de diodes Schottky et PN préalablement fabriquées. Les résultats obtenus constituent un moyen supplémentaire pour, non seulement localiser les défauts électriquement actifs, mais également les identifier. Les caractéristiques courant-tension des diodes montrent systématiquement l'impact du recuit sur le courant de fuite, paramètre sensible aux défauts. Plus spécifiquement, le courant de fuite se dégrade avec l'augmentation de la densité d'énergie. Ces mesures électriques ont permis également de mettre en évidence la présence de défauts localisés à l'interface liquide/solide, défauts ayant un fort impact sur les propriétés électriques des diodes. Les résultats sont en accord avec la littérature qui suggère la présence de lacunes à cette interface. Pour aller plus loin, des mesures de DLTS ont été effectuées et dévoilent, selon la localisation (zone fondue ou interface), des signatures singulières laissant présager plusieurs types de défautsThe micro-electronic domain is constantly evolving in response to the continuous emerging of new application fields as well as new users' needs. The fabrication of heavily-doped regions for ultra-shallow junctions is a major issue to ensure its evolution. In this context, new doping techniques allowing to obtain ultra-shallow junctions have been developed. Nanosecond laser annealing in "melt mode" is one of these techniques. Indeed, it allows a very strong local activation (on surface and in depth) and a uniform distribution of doping. This process used in laboratory since the 1980s for the realization of solar cells offers also new technological possibilities such as the development of 3D architectures. However, degradation of several parameters sensitive to laser-induced defects were observed, such as carrier mobility and reverse current in MOS transistors or carrier lifetime in the case of photovoltaic cells. In this context, this thesis proposes a rigorous study of the defects generated by laser annealing in two parts. The first part analyses the impact of the laser annealing on the physical properties, thanks to infrared and photoluminescence spectroscopy characterizations of bare silicon samples submitted to different annealing conditions. The study highlights the formation of defects following the laser process. Their identification allowed to confirm the introduction of oxygen and carbon impurities during the annealing. From this identification, the impurities were followed in depth by secondary ion mass spectrometry allowing to reveal an increase of their concentration and diffusivity when increasing the laser energy density and/or the number of laser pulses. At high energy, the oxygen concentration profiles show the presence of an immobile peak (in agreement with the known solubility limit value in liquid silicon) which are related to silicon cavities observed by transmission electron microscopy. The origin of these impurities is also discussed and the characterization of dedicated test vehicles allowed to identify the native oxide as the source of the impurities. The objective of second part is to evaluate the impact of laser annealing on the electrical properties of silicon devices thanks to the characterization of PN and Schottky diodes. The obtained results provide an additional mean to localize the electrically active defects but also to identify them. The current-voltage characteristics of diodes systematically show an impact of the annealing on the leakage current, which is a strongly defect-sensitive parameter. More specifically, the leakage current deteriorates with increasing the laser energy. These measurements have allowed also to highlight the presence of defects at the liquid/solid interface, defects which also have a strong impact on diodes electric properties. The results are in agreement with the literature which suggests the presence of vacancies at the interface. To go further on this study, DLTS measurements have been carried out and reveal, depending on their localization (melt zone or liquid/solid interface), singular signatures suggesting several types of defects
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Crutchley, Benjamin G. "Investigation into the efficiency limitations of InGaN-based light emitters." Thesis, University of Surrey, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.583342.
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Adelin, Brice. "Diodes laser tout cristal photonique émettant à 2,3 µm sur substrat GaSb." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30089/document.
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Les progrès récents des nanotechnologies permettent d'envisager de nouvelles générations de diodes laser. L'objectif de cette thèse est d'étudier l'apport des cristaux photoniques bidimensionnels pour explorer la faisabilité d'un réseau monolithique de diodes laser tout cristal photonique émettant au voisinage de 2,3 µm en filière GaSb. Chaque laser doit répondre à un certain nombre de critères : une émission monomode à une longueur d'onde stable et précise, une émission fine spectralement avec une puissance de sortie élevée, une longueur d'onde accordable, présentant aucun saut de mode sur la gamme d'accordabilité, un fonctionnement à température ambiante, sous pompage électrique et en régime continu. Ces critères répondent au cahier des charges de la technique de spectroscopie d'absorption à diodes laser accordables multiplexées (MTDLAS : Multiplexed Tunable Diode Laser Absorption Spectroscopy). La technique de MTDLAS est ici mise en œuvre pour les applications de détection de gaz dans le moyen infra-rouge (MIR), soit la gamme de longueur d'onde allant de 2 à 5 µm. Cette gamme de longueur d'onde présente plusieurs fenêtres de transparence (autour de 2,3 µm et de 3,4 à 4 µm) où l'absorption par la vapeur d'eau et le dioxyde de carbone est très faible. L'existence de ces fenêtres est mise à profit pour la détection de molécules gazeuses de l'atmosphère, telles que le monoxyde de carbone ou le méthane. Pour mes travaux de thèse, la longueur d'onde d'émission laser retenue est de 2,3 µm. Cette longueur d'onde correspond à la fenêtre de transparence pour la détection notamment du CH4, du CO et du HF. Ainsi, ce mémoire présente la conception de diodes laser tout cristal photonique, et le développement d'un procédé de fabrication de ces diodes lasers, qui a mené à la réalisation d'une série de composants. Nous montrons qu'une déformation de la maille photonique, associée à une optimisation de la largeur du guide, permet d'obtenir un fonctionnement monomode stable. Se basant sur ce principe, plusieurs géométries de mailles de cristaux photoniques ont été étudiées. Puis, nous nous attachons à lever le verrou technologique de la gravure profonde à fort rapport d'aspect dans les alliages AlGaAsSb. Pour cela, nous présentons des études paramétriques de gravure, conduisant à la mise au point d'un procédé optimisé de gravure profonde. Des profondeurs de gravure de 3,4 µm pour des trous de 370 nm de diamètre, soit un rapport d'aspect de plus de 9, ont ainsi pu être atteintes. Cette étape critique de gravure a été insérée dans un procédé technologique de fabrication de diodes laser tout cristal photonique, que nous avons mis au point. Cela a mené à la réalisation d'une série de composantsRecent advances in nanotechnology allow considering new generations of laser diodes. The purpose of this thesis is to study the contribution of two-dimensional photonic crystals to design and fabricate a monolithic array of laser diodes emitting near 2.3 µm in GaSb system. Each laser in the array has to respond to stringent criteria : a stable and precisely predefined single-mode emission wavelength, high output power, tunable wavelength with no mode hopping over the tunability range. Moreover, such device should operate at room temperature, under electrical pumping and continuous regime. These criteria respond to the specifications of the technique of Multiplexed Tunable Diode Laser Absorption Spectroscopy (MTDLAS). The MTDLAS technique is here implemented for gas sensing applications in the Mid-wavelength infrared (MidIR), corresponding to the wavelength range from 2 to 5 microns. This wavelength range contains two transparency windows (around 2.3 µm and from 3.4 to 4 µm), where the absorption by water vapor and carbon dioxide is reduced. The existence of these windows is harnessed for the detection of gaseous molecules in the atmosphere, such as carbon monoxide or methane. For my thesis work, the chosen wavelength of laser emission is 2.3 µm. This wavelength corresponds to a transparency window allowing detection of CH4, CO and HF. This dissertation presents the design of all photonic crystal laser diode, and the development of a manufacturing process of such device, which led to the production of a set of components. We show that the engineering of the photonic lattice combined with an optimization of the width of the laser waveguide provide stable, single-mode emission operation. Based on this principle, several geometries for photonic crystal lattice were studied. Then we tackle the technological challenge of deep etching with high aspect ratio in AlGaAsSb alloys. For this, we present parametric studies of etching, leading to the development of an optimized process for deep etching. We succeed to etch holes of 370 nm diameter and 3.4 µm depths, corresponding at an aspect ratio in excess of 9. We have developed a technological manufacturing process of all photonic crystal laser diodes, where this critical etching step has been successful inserted. This led to the realization of a set of components
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Perkins, David Edward. "Mode spectrum of laser diodes subject to optical feedback." Thesis, Bangor University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409838.
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Przeslak, Suzannah Jane Buteux. "Mid-infrared GaInSb/AlGaInSb strained quantum well laser diodes." Thesis, University of Bristol, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528098.
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Smowton, P. M. "The frequency stabilisation of laser diodes for industrial applications." Thesis, Cardiff University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319933.
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George, Adrian Alexander. "Carrier distributions in long wavelength quantum dot laser diodes." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/55180/.
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In this thesis I have produced results to show how carriers populate electronic states of InAs quantum dot (QD) laser diodes which operate near 1.3um, especially those which incorporate tunnel injection. I used the segmented contact method to produce modal absorption, modal gain, spontaneous emission and population inversion spectra as a function of photon energy. The spontaneous emission spectra for a high performance QD structure showed an increased population of the higher energy QD states than the tunnel injection structure. Analysis of the carrier distribution within the high performance QD structure revealed that the population of the QD states can be described by Fermi- Dirac statistics (thermally distributed) at 300K. As the temperature is lowered the electron distribution becomes clearly non-thermal, with clear regions of high inversion seen in the lower energy QD states. The higher inversion can be attributed to a reduced population of wetting layer states and as the temperature is lowered it becomes less likely for carriers to excite out of the dot states and thermally redistribute throughout the ensemble. The tunnelling injection structure was shown to exhibit unique features in its carrier distribution as compared to the high performance structure. At 300K the carrier distribution function is populated to thermal levels over energy ranges corresponding to a subset of the QD ground and first excited states. Between these energy ranges there is a region of under populated states shown by a region of low inversion. This suggests dots of a particular size within the ensemble are preferentially populated by the resonant tunnelling process. This results in a reduced spectral broadening of the emission from the QD ensemble. At higher temperature the selective population can still be observed, however it is less pronounced, presumably due to more efficient thermal distribution of electrons at higher temperature
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Al-Ghamdi, Mohammed Saad. "Optoelectronic properties of InP AlGaInP quantum dot laser diodes." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54948/.
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The aim of this thesis is to understand and optimise the optoelectronic properties of InP quantum dot laser diodes which operate in the range around 730nm required for various application such as the photodynamic therapy. The properties of wafers with two barrier widths, 8 and 6nm, each grown at different temperatures, 690, 710, 730 and 750T, and consisting of 5 layers of dots forms from different quantity of deposited material, 2, 2.5 and 3ML, are described and investigated. The laser and multisection devices of these structures are used to determine threshold current density, lasing wavelength, modal absorption, modal gain and spontaneous emission spectra. The modal absorption spectra show three different dot size distributions, small, large and very large dots. Their variation with growth temperature results in a blue shift accompanied by an increasing number of states while the variation with quantity of deposited material shows only an increase to the number of states. The lasing wavelength variation with growth temperature covers a range between 715–745nm. The threshold current density as a function of temperature for 2000/m long laser devices grown at temperature of 750°C exhibits a distinctive dependence on the operating temperature and becomes less pronounced when the growth temperature reduces. This is explained in terms of the carrier distributions in the quantum dot and quantum well states without invoking an effect from Auger recombination. The optimisation of threshold current density can be reached by using structures with higher barrier width grown at low temperature and deposited with high quantity of quantum dot material to minimise both the affect of the very large dot, which contain a number of defects associated with them, and carrier leakage from quantum dot to quantum well states. This reduces the room temperature threshold current density to ISO A/cm 2 for 2mm long lasers with uncoated facets.
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Thomas, Robert. "Monolithic coupled-cavity laser diodes for bio-sensing applications." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/31409/.
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This thesis describes an investigation into the potential of coupled-cavity semiconductor lasers for bio-sensing applications. This has involved the design and development of a fabrication process for a novel micro-fluidic coupled-cavity laser sensor. The efficiency of the etched inner laser facets of this device have been identified as a key determinant of the device behaviour. The multi-section gain characterization technique has been used to measure the efficiency of these facets to be η = 0.48 ± 0.13. Perturbation of the optical coupling between the two laser sections of the device can induce a wavelength shift in the laser output of Δλ = 20 ± 5 Å. This wavelength change is attributed to the difference in the threshold gain requirements of the coupled-cavity and individual cavity modes of the device. A multi-mode travelling wave rate equation model has been used to predict that the size of this effect can be maximized by optimizing the cavity lengths of the device. For the AlGaInP quantum well material used in this work the coupling effect is maximized by using the shortest cavity lengths possible that can still achieve laser action. The utility of including a segmented contact system to the coupled-cavity design has also been investigated. This modification enables wavelength tuning via the gain lever effect and self-pulsation through saturable absorption. A wavelength tuning range of Δλ = 1.2 ± 0.2 nm has been measured for a single cavity laser with a segmented contact length ratio of 4:1. This tuning behaviour has been attributed to the carrier density dependence of the net modal gain peak. Rate equation modelling has been used to interpret the self-pulsation behaviour of the segmented contact device and to demonstrate how optical pumping of a saturable absorber can increase the sensitivity of the coupled-cavity device.
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Brown, Martyn Rowan. "Numerical simulation of multiquantum barriers in 630nm laser diodes." Thesis, Swansea University, 2004. https://cronfa.swan.ac.uk/Record/cronfa42417.
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Red-emitting quantum well (QW) 630nm laser diodes have many potential applications in industry and medicine. The main profiteers would be in areas such as the development of critical memory, barcode readers and in the treatment of cancer. The limitation of the low inherent band offsets of the materials used to create such devices, gives rise to a high percentage of electron leakage via thermal activation in the QW active region. However, implementation of Multiquantum Barrier (MQB) into the p-type cladding region of the device enhances the effective conduction band discontinuity, thus increasing the reflection probability of carriers back into the device active region, consequently elevating output power of the laser device. A study of (Al[0.7].Ga[0.3])[0.5]ln[0.5]P/(Al[0.3]Ga[0.7])[0.5]ln[0.5]P (barrier/well) MQB has been investigated as a feasible material structure to enhance electron confinement within laser diodes in the 630nm regime. The structure was optimised theoretically based on the Gamma-X transport mechanisms, using an effective mass approximation and the transfer matrix technique. To accurately model such structures it is important to include possible distortion to the conduction band profiles induced by the different positions of the Fermi level with respect to the vacuum level. Thus, a dual-band device simulator was developed to model the band bending features, of both the Gamma and X minima. This novel simulator simultaneously solves the constituent expressions making up the drift-diffusion equation set, which is then solved iteratively with Schrodinger's equation to yield a self-consistent solution. Using these two simulation models a novel MQB structure is proposed which inhibits electron transmission across it in both the Gamma and X bands. Subsequently, this MQB structure predicts a theoretical effective enhancements of 50% the height of the intrinsic conduction band offset.
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LE, NEVE MARC. "Etude d'un laser nd : yag de forte energie pompe par diodes et declenche par absorbant saturable cr:yag." Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10133.
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Nous etudions un laser pompe transversalement par diodes et declenche passivement. L'extraction de fortes energies et la demonstration de rendements eleves sont recherches. Les capacites de differentes matrices dopees neodyme a offrir des rendements d'absorption eleves sont analysees en fonction de leur spectre d'absorption. A cet effet, un code de calcul prealablement qualifie experimentalement, ainsi que les caracterisations effectuees permettent d'acceder a la repartition spatiale de l'energie des diodes dans une section du barreau. Une etude parametree du depot d'energie est effectuee. Nous caracterisons ensuite les absorbants saturables (cr#4#+:yag, colorants bdn) par l'etude de la saturation de l'absorption. La mesure simultanee de la transmission et de l'intensite de fluorescence avec le cr#4#+, nous permet de remettre en cause l'importance de l'absorption dans l'etat excite et de proposer une autre origine a l'absorption residuelle de ces sites aux fortes fluences d'excitation. En declenchement actif, le laser demontre une energie de sortie disponible de 80 mj soit un rendement optique d'environ 10%. Ces resultats sont bien ajustes a l'aide des equations du bilan. Le fonctionnement de ce laser est totalement multimode (longitudinal et transverse). Puis, nous etudions le declenchement passif. Le resonateur plan-concave multimode de base presente un comportement spatio-temporel tres complexe et non reproductible. L'impulsion de sortie comporte plusieurs composantes temporelles distinctes. La repartition d'energie dans le faisceau ne reproduit nullement la carte de depot d'energie. La competition entre les modes transverses est a l'origine de ce comportement. Pour s'en affranchir, il faut tendre vers un oscillateur monomode transverse. Nous y parvenons en definissant des cavites dont le rayon du mode fondamental est eleve. Ainsi, avec une cavite telescopique nous obtenons des impulsions stables temporellement et spatialement, tout en offrant des valeurs de rendement et d'energie interessantes. En declenchement actif et passif, les perspectives d'optimisation du rendement du laser sont egalement quantifiees
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Maurin, Isabelle. "Etude du bruit quantique dans les lasers à semi-conducteurs (VCSELs et diodes laser)." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2002. http://tel.archives-ouvertes.fr/tel-00001605.
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Nous étudions en détail le bruit quantique dans les microlasers semi-conducteurs à cavité verticale : les VCSELs, dont l'acronyme anglais est Vertical-Cavity Surface-Emitting Lasers. Ces lasers ont la particularité d'émettre des faisceaux avec plusieurs modes transverses au-dessus du seuil. Lorsqu'un seul mode transverse, polarisé linéairement oscille, nous démontrons théoriquement aussi bien qu'expérimentalement l'importance du bruit de l'émission dans la direction de polarisation orthogonale pour la caractérisation du bruit d'intensité. Lorsque deux modes transverses polarisés linéairement et orthogonalement oscillent, nous étudions la structure spatiale transverse du bruit d'intensité. Nous développons un modèle quantique qui donne correctement l'allure du bruit d'intensité.Nous rapportons également dans cette thèse l'étude du bruit quantique dans les diodes laser. Par rapport au modèle standard des lasers à deux niveaux, ces lasers présentent un excès de bruit à fort courants. Nous démontrons expérimentalement et théoriquement que cet excès de bruit provient des fluctuations du courant à l'intérieur de la diode laser.
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Maurin, Isabelle. "Étude du bruit quantique dans les lasers à semi-conducteurs (VCSELs et diodes laser)." Paris 6, 2002. https://tel.archives-ouvertes.fr/tel-00001605.
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Bradunas, John J. "Design of a stabilized, dc-powered analog laser diode driver." Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA238596.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, September 1990.Thesis Advisor(s): Powers, John P. Second Reader: Michael, Sherif. "September 1990." Description based on title screen viewed on December 17, 2009. DTIC Descriptor(s): Semiconductor lasers, amplifiers, output, optical properties, environments, degradation, monitoring, communication equipment, modular construction, alternating current, optical communications, lasers, thermistors, drives, transmitters, power, circuits, direct current, photodiodes, analog systems, diodes, fiber optics. DTIC Identifier(s): Semiconductor lasers, intensity modulation, theses. Author(s) subject terms: Semiconductor laser diode; thermoelectric cooling; laser diode driver; intensity modulation. Includes bibliographical references (p. 103-105). Also available in print.
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Chern, Kevin Tsun-Jen. "Fabrication and Characterization of Narrow-Stripe Quantum Well Laser Diodes." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/34717.
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More efficient semiconductor lasers will be needed in tomorrowâ s applications.
These lasers can only be realized through the application of new device processing
techniques, designed to restrict current, carrier, and/or photon flow through the lasing
cavity. This work aims to evaluate a non-conventional stripe laser processing technique
which has the potential for effective current and possibly carrier confinement at low cost.
This technique, referred to as hydrogen passivation, involves exposing laser material to a
low energy hydrogen plasma, causing hydrogen ions to bind to charged acceptor and
donor atoms. Such binding compensates the electrical activity of these dopant atoms and
thereby increases the resistance of the exposed material. Optical confinement can also be
achieved (subsequent to hydrogenation) by using a simple wet-etching process to form a
lateral waveguide. Stripe lasers fabricated via hydrogen passivation have been
demonstrated previously; however, the benefits of this method have not been fully
explored or characterized. Our work aims to quantify the degree of current and carrier
confinement provided by this technique. The cleaved cavity method of analysis is used to
extract laser parameters via direct measurement. These parameters are then compared
against those obtained from more conventional stripe lasers to identify improvements that
have accrued from using hydrogen passivation.Master of Science
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Peschke, Martin. "Laser diodes integrated with electroabsorption modulators for 40 Gb/s data transmission." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-55841.
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Claps, Ricardo Javier. "Novel developments in laser diode raman spectroscopy /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
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Czesnakowska, Ada. "Développement d'une source de lumière blanche grâce au couplage d'une diode laser et d'un luminophore adaptés." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30180/document.
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Ces dernières années les semi-conducteurs à base de InGaN sont devenus attractifs pour des applications d'éclairage. Les sources blanches à base de LED sont de plus en plus utilisées en raison de leur petite taille, leur longue durée de vie et leur faible consommation d'énergie. Malheureusement les LED utilisées dans ces dispositifs subissent une perte de rendement quantique externe quand leur courant d'alimentation augmente. Ceci se traduit par un décalage du maximum d'émission ainsi qu'un élargissement spectral. Ces variations d'émission impactent la conversion de lumière bleue en lumière blanche, ce qui diminue l'efficacité du procédé. Une méthode alternative pour obtenir de la lumière blanche en travaillant à forte puissance serait l'utilisation de diodes laser (DL) à la place des LED. Contrairement aux LED, elles sont moins affectées par les pertes d'efficacité. La puissance lumineuse et le rendement quantique externe des diodes laser augmentent linéairement avec le courant d'alimentation, ce qui maintient la stabilité de la lumière blanche produiteIn past few years InGaN-based semiconductors have attracted much more attention for application in solid-state lighting sources. Recently, their usage is constantly increasing on worldwide market. High-brightness white LEDs have been used due to their size, long life and energy saving. However, LEDs used in light sources suffer from a loss in external quantum efficiency as an operating current increases. This loss may lead to a shift in peak emission wavelength and broadening of emission spectrum. Laser diodes, in contrary to LEDs, do not suffer this loss. The output power increases linearly with injection current. Moreover, they can reach higher luminosity, for the same power, than LEDs. Additionally, laser-based devices can be operated in reflection mode, allowing for the phosphor to be placed on a reflection substrate that may also act as a heat sink to effectively dissipate heat away from the phosphor
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Smith, Edward J. "The diode array velocimeter." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09122009-040337/.
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