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1
Sun, Yifan. "Theory of mode-locked lasers based on non-conventional cavity modes." Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASP003.
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Cette thèse de doctorat porte principalement sur la dynamique et la robustesse d’un nouveau concept de verrouillage de mode dans les nanolasers semi-conducteurs ultracompacts. Un tel nanolaser présente des modes ermites-gaussiens créés par une cavité photonique harmonique pour confiner la lumière. Cela permet de mapper la cavité optique en oscillateur harmonique de mécanique quantique, avec des fréquences propres régulièrement espacées, une condition essentielle pour le verrouillage de mode. La période de verrouillage de mode est contrôlée par la conception du potentiel photonique, et non par la longueur de la cavité. Les régimes non linéaires possibles sont décrits par l’équation de Gross-Pitaevskii avec un potentiel parabolique et des termes non linéaires décrivant le gain et l’absorption. Pour étudier ces comportements dynamiques, des simulations numériques directes sont principalement mises en œuvre. Tout d’abord, la compétition de mode pour le gain entre les modes ermites et gaussiens en l’absence d’absorption saturable est étudiée. Deuxièmement, on prévoit que le verrouillage des modes se produira avec une saturation instantanée du gain et de l’absorption sur un large éventail de paramètres, correspondant à l’émergence d’une soliton dissipative. Troisièmement, dans le régime de saturation non instantanée du gain et de l’absorption, différents comportements dynamiques du nanolaser sont obtenus en faisant varier le gain et l’absorption. Ces différents régimes, y compris la commutation Q, le verrouillage de mode à commutation Q et le verrouillage de mode CW, sont décrits en détail. L’influence du facteur Henry sur le verrouillage de mode est également abordée. Quatrièmement, la robustesse du verrouillage de mode des modes ermite et gaussien au désordre de la cavité harmonique est étudiée en détail, y compris l’effet de la non-parabolicité du potentiel et les erreurs aléatoires dans la forme du potentielThis PhD thesis mainly addresses the dynamics and the robustness of a novel concept of mode locking in ultracompact semiconductor nanolasers. Such a nanolaser exhibits Hermite-Gaussian modes created by a harmonic photonic cavity to confine light. This maps the optical cavity into quantum mechanical harmonic oscillator, with evenly spaced eigenfrequencies, an essential requirement for mode locking. The possible nonlinear regimes are described by the Gross-Pitaevskii equation with a parabolic potential and nonlinear terms describing gain and absorption. To investigate these dynamical behaviors, direct numerical simulations are mainly implemented. Continuation calculations are also performed using pde2path.First, the mode competition for gain among Hermite-Gaussian modes in the absence of saturable absorption is investigated and shown to be very different from usual resonators.Second, mode locking is predicted to occur with instantaneous saturation of gain and absorption over a broad range of parameters, corresponding to the emergence of dissipative soliton and multisoliton solutions. The mode locking period is controlled by the design of the photonic potential, and not by the cavity length. The dissipative soliton is well described by the coherent state of a quantum mechanical oscillator, namely a Gaussian envelope oscillating without deformation.Third, in the regime of noninstantaneous gain and absorption saturation, different dynamical behaviors of the nanolaser are obtained by varying the gain and the absorption. These different regimes, including Q-switching, Q-switched mode locking, and CW mode locking, are described in detail, illustrating the rich physics of this nonlinear system. The influence of the Henry factor on the mode locking is also discussed. Moreover, similar dynamical behaviors using spatially separated gain and absorber sections inside the cavity are obtained.Fourth, the robustness of mode locking of the Hermite-Gaussian modes to the disorder of the harmonic cavity is investigated in details. It includes the effect of non-parabolicity of the potential and the random errors in the shape of the potential
2
Magné, Julien. "Traitement optique du signal émis par un laser à fibre mode-locked passif : application à la multiplication et à la sculpture d'impulsions." Doctoral thesis, Université Laval, 2007. http://hdl.handle.net/20.500.11794/19285.
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Taurand, Geneviève. "Mesures de réflectométrie prises avec un interféromètre à peignes de fréquence." Thesis, Université Laval, 2010. http://www.theses.ulaval.ca/2010/27255/27255.pdf.
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Salhi, Mohamed. "Etude des lasers à fibre en régime verrouillé en phase par rotation non-linéaire de la polarisation." Angers, 2004. http://www.theses.fr/2004ANGE0018.
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Les lasers à fibre dopée sont de très bons candidats pour la réalisation de lasers à impulsions courtes. En effet, les largeurs spectrales sont relativement importantes et de plus, plusieurs techniques existent pour verrouiller en phase de manière passive. Dans ce travail, nous avons étudié théoriquement un laser à fibre verrouillé en phase par la technique de rotation non linéaire de la polarisation. La configuration comprend un polariseur placé entre deux contrôleurs de polarisation dans une cavité en anneau unidirectionnelle. Le modèle développé se réduit à une équation de type Ginzburg-Landau complexe et permet d'obtenir des solutions analytiques dans le cas des régimes continu et à impulsions courtes. Le passage d'un régime à l'autre se fait en tournant les contrôleurs de polarisation. Ce modèle est en très bon accord avec les résultats obtenus avec un laser à fibre dopée ytterbium. L'étude a aussi portée sur le laser erbium ainsi que sur le laser à impulsions étiréesRare-earth doped fibers are very good candidates to develop short-pulses lasers. Indeed, they exhibit very large optical spectra and, in addition, various methods to achieve passively mode-locking can be used. In this work, we have theoretically investigated a fiber laser passively mode-locked through nonlinear polarization rotation. The laser contains a polarizer placed between two polarization controllers in a unidirectional ring cavity. The model reduces to a complex Ginzburg-Landau equation and allows obtaining analytic solutions in the continuous or mode-lock regimes. Unstable regime is also obtained. The orientation of the polarization controllers allows switching from one regime to the other. The model is in very good agreement with the experimental results obtained in the case of the ytterbium-doped double-clad fiber laser. Both the cases of the erbium-doped and the stretched-pulse lasers have been investigated
5
Resan, Bojan. "DISPERSION-MANAGED BREATHING-MODE SEMICONDUCTOR MODE-LOCKED RING LASER." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2907.
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A novel dispersion-managed breathing-mode semiconductor mode-locked ring laser is developed. The "breathing-mode" designation derives from the fact that intracavity pulses are alternately stretched and compressed as they circulate around the ring resonator. The pulses are stretched before entering the semiconductor gain medium to minimize the detrimental strong integrating self-phase modulation and to enable efficient pulse amplification. Subsequently compressed pulses facilitate bleaching the semiconductor saturable absorber. The intracavity pulse compression ratio is higher than 50. Down chirping when compared to up chirping allows broader mode-locked spectra and shorter pulse generation owing to temporal and spectral semiconductor gain dynamics. Pulses as short as 185 fs, with a peak power of ~230 w, and a focused intensity of ~4.6 gw/cm2 are generated by linear down chirp compensation and characterized by shg-frog method. To our knowledge, this is the highest peak power and the shortest pulse generation from an electrically pumped all-semiconductor system. The very good agreement between the simulated and the measured results verifies our understanding and ability to control the physical mechanisms involved in the pulse shaping within the ring cavity. Application trends such as continuum generation via a photonic crystal fiber, two-photon fluorescence imaging, and ultrafast pulse source for pump-probe experiments are demonstrated.Ph.D.
Other
Optics and Photonics
Optics
6
Williamson, Craig A. "Mode locking of novel semiconductor lasers." Thesis, University of Exeter, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.480992.
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Mihoubi, Zakaria. "Mode-locked surface emitting semiconductor lasers." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/72372/.
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Optically-Pumped Vertical External Cavity Surface Emitting Lasers (OP-VECSELs) arc novel semiconductor-based lasers that have many advantages over other lasers in terms of the power scalability, good beam quality, compactness and low cost they can offer. They can be passively mode-locked with a Semiconductor Saturable Absorber Mirror (SESAM) to produce transformnm-limnited sub-300 fs pulses directly from the laser cavity with high repetition rates. This thesis describes an experimental and theoretical investigation of OP-VECSELs. A full characterization is done on a VECSEL sample to understand time physics behind its operation iii the Continuous Wave (CW) mode and in the mode—locked mode. Then. a numerical model that, for the first time, shows the role of the Optical Stark Effect (OSE) in shaping the mode-locked pulses in the approach to steady state is introduced. TIme model results are broadly consistent with observed behavior of our rriode-locked VECSELs. Here, I also report the first coherent generation and detection of terahertz radiation using all-semiconductor components. Radiation with a bandwidth of 0.8 THz has been generated using sub-500 fs pulses with an average power of 20 mW from a mode-locked VECSEL which contains InGaAs quantum wells arid an LT-GaAs/InGaAs emitter/receiver antenna in a Terahertz Time Domain Spectrometer (THz-TDS) setup. The first mode locked OP-VECSEL at 830 rim is reported here. The combination of a GaAs quantumrm well—based gain sample and SESAI\I yielded an output with an average power of 5 mW and 15 ps-long pulses at a repetition rate of 1.9 GHz. A pumping module used to drive the laser was built for this purpose by combining the output of two commercial 665 rim diode lasers.
8
Gordon, Reuven. "Lateral mode frequency locking in semiconductor lasers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/MQ45425.pdf.
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Irving, Clive Russell. "Vernier injection mode switching of diode lasers." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239128.
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Cox, Benjamin Paul. "New models for multilateral mode semiconductor lasers." Thesis, University of Birmingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433743.
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Mosaad, N. R. M. "Picosecond measurements with mode-locked CW lasers." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382491.
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Born, Christopher J. "Nonlinear mode interactions in semiconductor ring lasers." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432349.
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13
Weber, Thomas. "Powerful diode-pumped single-mode fiber lasers /." [S.l : s.n.], 1995. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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14
Arkhipov, Rostislav. "Modeling of mode-locking regimes in lasers." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17190.
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In dieser Arbeit werden einige Probleme im Zusammenhang mit der Erzeugung ultrakurzer Pulse in modengekoppelten Lasern unter Verwendung analytischer und numerischer Methoden theoretisch untersucht. Weiterhin werden einige Resultate über die Strahlung resonanter Medien, welche durch einen ultrakurzen Überlichtgeschwindigkeits-Lichtpuls angeregt werden, dargestellt.In this thesis current problems related to the generation of short optical pulses in mode-locked lasers are considered in a theoretical context. We use numerical and analytical methods to study these problems. Additionally, the problem of resonant medium radiation excited by ultrashort light pulse propagating at superluminal velocity is investigated.
15
Shtyrkova, Katia. "Fully Integrated CMOS-compatible mode-locked lasers." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115641.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.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 (pages 191-205).
The field of integrated photonics has already revolutionized optical communications and is making rapid advances in signal processing, light detection and ranging, optical sensing, bio-medical diagnostics and imaging, and military-related applications. Large and complex radio-frequency and optical systems could be potentially replaced with compact, power-ecient, alignment-free, cost-effectively mass-produced integrated photonics components. An on-chip high repetition-rate mode-locked laser is a key enabler of many integrated photonics applications, such as all-optical sampling, on-chip frequency combs, low phase noise microwave oscillators, photonic ADCs and others. First-ever fully-integrated on-chip mode-locked lasers are demonstrated in this work, fabricated using a CMOS-compatible process. The lasers have no o-chip elements other than the pump laser, which could be easily co-packaged. 1900nm and 1550nm lasers are designed, fabricated and characterized. For 1900nm central wavelength lasers, several dierent laser configuration are demonstrated, with repetition rates of 690MHz and 1.2GHz. Q-switched, Q-switch-mode-locked, and CW mode-locked laser operation was demonstrated, with the shortest pulse durations of 250fs. The smallest foot-print of one laser is 23.6mm x0.78mmx0.6mm. In addition, first-ever fully-on-chip CMOS-compatible mode-locking element based on Kerr nonlinearity is demonstrated for 1550nm and 1900nm laser wavelengths. Demonstrated modulation depths for 1900nm and 1550nm mode-locking devices are 9% and 2.5% respectively. The work in this thesis presents the first-ever demonstration of fully-onchip CMOS compatible mode-locking device, as well as first-ever CMOS-compatible mode-locked lasers with no o-chip components.
by Katia Shtyrkova.
Ph. D.
16
Callahan, Patrick T. Ph D. (Patrick Timothy) Massachusetts Institute of Technology. "Integrated waveguide devices for mode-locked lasers." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/117835.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.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 (pages 129-134).
Mode-locked lasers can provide a stable source of optical pulses with intrinsically low timing jitter, and as such have a broad range of important applications, both as sources of low-noise microwave signals and as the key enabling technology for optical frequency combs. Integrating such laser systems onto a chip using silicon photonics will dramatically reduce size and cost, thus increasing the accessibility of this technology for widespread deployment. Mode-locked lasers can also serve as master oscillators within distributed timing synchronization systems. These systems require precise measurement and control of timing drift and jitter, which can be performed by balanced optical cross-correlation. Integrated implementations of these timing detectors using waveguides in nonlinear crystals will significantly increase efficiency and sensitivity, enabling higher performance for synchronization. In this thesis, I have developed an integrated mode-locked laser on a CMOS-compatible silicon photonics platform, as well as an integrated balanced optical cross-correlator for use in timing jitter performance monitoring and timing distribution systems.
by Patrick T. Callahan.
Ph. D.
17
Zhu, Gongwen. "Q-switched and Mode-locked Mid-IR Fiber Lasers." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/578593.
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Mid-infrared (IR) lasers (2-12 μm) have found tremendous applications in medical surgeries, spectroscopy, remote sensing, etc. Nowadays, mid-IR emissions are usually generated from semiconductor lasers, gas lasers, and solid-state lasers based on nonlinear wavelength conversion. However, they usually have disadvantages including poor beam quality, low efficiency, and complicated configurations. Mid-IR fiber lasers have the advantages of excellent beam quality, high efficiency, inherent simplicity, compactness, and outstanding heat-dissipating capability, and have attracted significant interest in recent years. In this dissertation, I have studied and investigated Q-switched and mode-locked fiber lasers in the mid-IR wavelength region. My dissertation includes six chapters: In Chapter 1, I review the background of mid-IR lasers and address my motivation on the research of mid-IR fiber lasers; In Chapter 2, I present the experimental results of microsecond and nanosecond Er³⁺-doped and Ho³⁺-doped fiber lasers in the 3 μm wavelength region Q-switched by Fe²⁺:ZnSe and graphene saturable absorbers. In Chapter 3, Q-switched 3 μm laser fiber amplifiers are investigated experimentally and theoretically and their power scaling are discussed. In Chapter 4, a graphene mode-locked Er³⁺-doped fiber lasers at 2.8 μm with a pulse width < 50 ps is presented. In Chapter 5, extending the spectral range of mid-IR fiber lasers by use of nonlinear wavelength conversion is addressed and discussed. I have proposed 10-watt-level 3-5 μm Raman lasers using tellurite fibers as the nonlinear gain medium and pumped by our Er³⁺-doped fiber lasers at 2.8 μm. In the last chapter, the prospect of mid-IR fiber laser is addressed and further research work is discussed.
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McLeod, Duncan Peter. "Seismic effects in ring lasers and transverse mode selection in helium-neon lasers." Thesis, University of Canterbury. Physics and Astronomy, 2000. http://hdl.handle.net/10092/1999.
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The effect of seismic activity on large ring laser gyroscopes is determined. In particular the novel use of ring laser gyros as detectors of the rotational components of earthquake waves is investigated. It is found that lasers such as C-II which are well isolated from mechanical strain of the ground are effectively sensitive only to the rotational components of seismic waves. Tilt and bulk strain in the laser body are found to be negligible. Fourier analysis of earthquake data from C-I gives very good agreement with the modelled effects. The use of the auto-regressive AR(2) model as a superior alternative to Fourier analysis is investigated. It is found that such an approach is much more sensitive and gives access to a hitherto unavailable parameter, the Sagnac linewidth. The effects on the Sagnac frequency and its linewidth are found to be in excellent agreement with earthquake data recorded from the laser C- II. Microseismic noise induced in the ground by oceanic wave action on coastlines and the possible effects on ring laser noise levels are determined. It is found that typical amplitudes of microseismic waves are many orders of magnitude too weak to be manifested in frequency spectra of ring laser gyroscopes and lie far below the ultimate quantum noise limit for such lasers. A model is developed of helium-neon lasers operating at 632.8 nm to determine the radial distribution of the population inversion density. The simplest model, requiring the least number of atomic levels to be included, is found which will account for the induction of a central minimum in the distribution due to increasing pumping rate. An extension of the gain expression for laser modes is used to determine the gains for different transverse modes. The expected variations of the first and last oscillating transverse modes in a purpose built linear laser, L1, are found to be in good agreement with the model. With the inclusion of astigmatism the model is extended to ring lasers and the expected mode behaviour is predicted and recommendations for the operation of such lasers is made. The behaviour of very large ring lasers, with perimeters of tens of metres, are investigated. A description of the design and commissioning of the large high-quality linear laser, designated Ll is given.
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Scheller, Maik, Caleb W. Baker, Stephan W. Koch, and Jerome V. Moloney. "Dual-Wavelength Passively Mode-Locked Semiconductor Disk Laser." IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2016. http://hdl.handle.net/10150/621738.
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A dual-wavelength mode-locked semiconductor
vertical-external-cavity-surface-emitting laser is demonstrated.
A semiconductor saturable absorber mirror allows for simultaneous
mode locking of pulses centered at two center wavelengths
with variable frequency spacing. The difference-frequency control
is achieved with an intracavity etalon. Changing the finesse of
the etalon enables the adjustment of the pulse duration between
6 and 35 ps. The emitted two-color pulses are modulated by a
beat frequency in the terahertz range. Self-starting mode-locking
with 0.8-W average output power is demonstrated.
20
Maes, Carl F. "Transverse mode properties of lasers with Gaussian gain." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289894.
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The modes and beam characteristics of a Gaussian gain laser resonator are analyzed. Such a gain is typically associated with an end pumped solid state laser. The beam propagation method is used to find the eigenmodes. The eigenmodes are non Gaussian in appearance and differ greatly from the modes of the same cavity with a quadratic gain. It is found that the cavity geometry strongly influences mode formation around degenerate cavity geometries throughout a broad range of operational parameters. The beam propagation method is used to evolve the field through the resonator, resulting in computation of the nonorthogonal eigenmodes. This permits evaluation of the excess noise dependence on geometric cavity parameters such as length and focal length. It is shown that the beam quality M² and Petermann K factor are related and are anticorrelated at degeneracies. An explanation is given based on the self Fourier transforming properties of degenerate cavity locations. It is shown how the empty cavity properties of transverse mode degeneracies are not revealed with a quadratic gain, but are strikingly present with a Gaussian gain. A confocal cavity is studied in detail and found to have the property that forces K to unity even in the presence of strong gains and narrow pump widths. The interplay between the diffraction effects of a geometrically stable cavity and the Gaussian gain will be studied to reveal the nature and implications of the non-normal modes encountered.
21
Boone, A. W. "Theory of two-photon and two-mode lasers." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336042.
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Foreman, Hannah D. "Mode-locked vertical-external-cavity surface emitting lasers." Thesis, University of Southampton, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438526.
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Tamura, Kohichi Robert. "Additive pulse mode-locked erbium-doped fiber lasers." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11851.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (leaves 155-168).
by Kohichi Robert Tamura.
Ph.D.
24
Kennedy, Gordon T. "Novel mode-locking techniques for colour-centre lasers." Thesis, University of St Andrews, 1994. http://hdl.handle.net/10023/13757.
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The work reported in this thesis is primarily concerned with the generation of ultrashort pulses from a NaCl:OH- colour-centre laser. Active mode locking of the NaCl:OH- laser by synchronous pumping and acousto-optic loss modulation was characterised in detail. Synchronously mode-locked pulses of 8 ps duration were compressed to 250 fs in an anomalously-dispersive optical fibre and a novel soliton-effect pulse compressor was constructed from a nonlinear fibre-loop mirror. Using this device, the synchronously mode-locked pulses were compressed to 300 fs with no discernible background radiation. The NaChOH- laser was coupled-cavity-mode locked using both nonlinear Fabry- Perot and Michelson cavity configurations, and pulses of 110 fs duration were obtained. A sawtooth amplitude modulation of the laser output was observed. This modulation, which arose from the beating of the mode-locked Nd:YAG pump laser and NaCl:OH- laser pulse trains, was avoided by frequency-referencing the colour-centre laser to the pump laser. A characterisation of the phase noise of the frequency-referenced, coupled-cavity mode- locked laser was performed. By replacing the frequency synthesiser for the pump laser mode locker with a crystal oscillator, the phase noise of both the Nd:YAG pump laser and the NaCl:OH- colour-centre laser were reduced by two orders of magnitude. The technique of self-mode locking was successfully applied to the NaCl:OH- laser. For this laser, it was necessary to include a rod of high-nonlinearity lead-silicate glass in the laser cavity to achieve sufficient self focusing for self-mode locking. Stable mode-locking was initiated by a regenerative acousto-optic modulation and pulses of 95 fs were obtained. The thesis concludes with descriptions of some experiments performed using a mode-locked NaCl:OH- laser and a KCl:TiO(1) colour-centre laser. Efficient pulsed Raman amplification in an optical fibre was achieved by using an optical fibre thats group-velocity dispersion was the same for both the pump and signal wavelengths. By co-propagating pulse trains from the KCl:TiO(1) and NaCl:OH- lasers through a semiconductor optical amplifier cross phase modulation was observed. Ultrafast all-optical switching using the nonlinearity at half the bandgap was demonstrated for an GaA1As integrated interferometer. This nonlinearity was subsequently used to coupled-cavity mode lock the KCl:TiO(1) colour-centre laser.
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Grant, Robert S. "Mode-locked colour-centre lasers and their application." Thesis, University of St Andrews, 1992. http://hdl.handle.net/10023/13752.
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The passive and coupled-cavity mode locking of a LiF:F2+ colour-centre laser was studied. Pulses of less than 180 fs were obtained in the 0.85 mum spectral region by passive mode-locking using the saturable absorber dye IR140. Coupled-cavity mode locking, where a length of optical fibre was incorporated in an external control cavity, resulted in the generation of 1.5 ps duration pulses. Active and coupled-cavity techniques were applied to a KCl:TiO(1) colour-centre laser operating in the 1.5 mum spectral region. Coupled-cavity mode locking was obtained using either Fabry-Perot or Michelson interferometer arrangements. Although either arrangement generated similar pulse durations, the Michelson scheme was found to be more stable. Pulse durations of less than 100 fs were routinely obtained from either arrangement by using small-core fibre in which the dispersion minimum coincided with the laser operating wavelength. The KCl:TiO(1) laser was used to study various absorptive and refractive nonlinearities in a 1.5 mum InGaAsP optical amplifier. Pulse distortion caused by gain saturation and loss saturation was studied in the temporal and spectral domains. In addition, cross-phase modulation related to gain saturation was investigated. Self-phase modulation caused by an ultrafast refractive nonlinearity has been observed for the first time, and its nonlinear coefficient n2 was deduced to be -2 x 10-11cm2W-1. Coupled-cavity mode locking of the KCl:TiO(1) laser was also obtained when the InGaAsP amplifier was used, with pulses as short as 280 fs. Self-starting operation was achieved by eliminating parasitic optical feedback from the device facets. Mode locking was observed for amplifier drive currents either above or below transparency, suggesting that saturable gain and saturable loss respectively were the dominant nonlinearities exploited. The synchronous and coupled-cavity mode locking of a NaCl:OH- laser operating near 1.57 mum was investigated. Coupled-cavity mode locking using an optical fibre was achieved, but was accompanied by a sawtooth modulation in power output (or pulse duration) related to the short gain storage time of NaC1;OH-. This was circumvented by substituting the InGaAsP amplifier for the fibre to obtain self-starting mode locking.
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Ivanenko, Aleksey. "Ultra-long mode-locked Er-droped fibre lasers." Thesis, Aston University, 2013. http://publications.aston.ac.uk/20855/.
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The development of ultra-long (UL) cavity (hundreds of meters to several kilometres) mode-locked fibre lasers for the generation of high-energy light pulses with relatively low (sub-megahertz) repetition rates has emerged as a new rapidly advancing area of laser physics. The first demonstration of high pulse energy laser of this type was followed by a number of publications from many research groups on long-cavity Ytterbium and Erbium lasers featuring a variety of configurations with rather different mode-locked operations. The substantial interest to this new approach is stimulated both by non-trivial underlying physics and by the potential of high pulse energy laser sources with unique parameters for a range of applications in industry, bio-medicine, metrology and telecommunications. It is well known, that pulse generation regimes in mode-locked fibre lasers are determined by the intra-cavity balance between the effects of dispersion and non-linearity, and the processes of energy attenuation and amplification. The highest per-pulse energy has been achieved in normal-dispersion UL fibre lasers mode-locked through nonlinear polarization evolution (NPE) for self-modelocking operation. In such lasers are generated the so-called dissipative optical solitons. The uncompensated net normal dispersion in long-cavity resonatorsusually leads to very high chirp and, consequently, to a relatively long duration of generated pulses. This thesis presents the results of research Er-doped ultra-long (more than 1 km cavity length) fibre lasers mode-locked based on NPE. The self-mode-locked erbium-based 3.5-km-long all-fiber laser with the 1.7 µJ pulse energy at a wavelength of 1.55 µm was developed as a part of this research. It has resulted in direct generation of short laser pulses with an ultralow repetition rate of 35.1 kHz. The laser cavity has net normal-dispersion and has been fabricated from commercially-available telecom fibers and optical-fiber elements. Its unconventional linear-ring design with compensation for polarization instability ensures high reliability of the self-mode-locking operation, despite the use of a non polarization-maintaining fibers. The single pulse generation regime in all-fibre erbium mode-locking laser based on NPE with a record cavity length of 25 km was demonstrated. Modelocked lasers with such a long cavity have never been studied before. Our result shows a feasibility of stable mode-locked operation even for an ultra-long cavity length. A new design of fibre laser cavity – “y-configuration”, that offers a range of new functionalities for optimization and stabilization of mode-locked lasing regimes was proposed. This novel cavity configuration has been successfully implemented into a long-cavity normal-dispersion self-mode-locked Er-fibre laser. In particular, it features compensation for polarization instability, suppression of ASE, reduction of pulse duration, prevention of in-cavity wave breaking, and stabilization of the lasing wavelength. This laser along with a specially designed double-pass EDFA have allowed us to demonstrate anenvironmentally stable all-fibre laser system able to deliver sub-nanosecond high-energy pulses with low level of ASE noise.
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Pusino, Vincenzo. "High power, high frequency mode-locked semiconductor lasers." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5174/.
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Integrated mode-locked laser diodes are effective sources of periodic sequences of optical pulses, which have always been of great interest for a range of spectroscopy, imaging and optical communications applications. However, some disadvantages prevent their widespread use, such as the restricted tuning of their repetition rate and their output power levels never exceeding a few mW. This thesis reports on the work done to address those limitations. Two main findings are presented, the first being the generation of ultra-high repetition rate optical signals through external injection of two continuous wave signals. This mechanism is much simpler than other techniques previously proposed to increase the repetition rate of monolithic modelocked laser, and has proved successful in generating optical signals up to quasi-THz. It is based on injection of two continuous wave signals whose spacing is an integer multiple of the pulsed cavity free spectral range and whose injection wavelengths coincide with two of the monolithic laser modes. This technique allows discrete tunability of the repetition rate with a step equal to the injected cavity free spectral range, and the injected laser has been shown to lock up to a repetition rate of 936 GHz, corresponding to 26 times that of the free-running semiconductor laser (36 GHz). The presented scheme is suitable for integration, opening the way for a successful on-chip generation of ultra-high repetition rate optical signals exploiting coupled cavity phenomena. The second main finding of this thesis regards the changes induced on the pulsed operation of monolithic passively mode-locked lasers by a blue bandgap detuning applied to their saturable absorber. The quantum well intermixing technique has been used for attaining an area-selective bandgap shift on the fabricated chip, being fully postgrowth. The lasers with a detuned absorber were found to have an extended range of gain section currents and absorber voltages in which stable mode-locking operation took place. Furthermore, a comparison of mode-locked devices fabricated on the same chip, respectively with and without a bandgap detuned absorber, showed that the emitted pulses had greater peak power and were less affected by optical chirp when the bandgap of the absorbing section was shifted. A new intermixing technique has also been developed as part of this work to address some inconsistencies of the pre-existing one; the newly introduced approach has been found to provide better spatial resolution and a more precise control of the attained bandgap shift.
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Chang, J. T. "Active mode-locking of semiconductor lasers and study of optical amplification in diode lasers." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/46995.
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Gloag, Andrew John. "Tunable erbium doped fibre lasers." Thesis, University of Strathclyde, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249838.
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Archundia-Berra, Luis. "EXTERNAL CAVITY MULTIWAVELENGTH SEMICONDUCTOR MODE-LOCKED LASER GAIN DYNAMICS." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3078.
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External cavity semiconductor mode-locked lasers can produce pulses of a few picoseconds. The pulses from these lasers are inherently chirped with a predominant linear chirp component that can be compensated resulting in sub-picosecond pulses. External cavity semiconductor mode-locked lasers can be configured as multiwavelength pulse sources and are good candidates for time and wavelength division multiplexing applications. The gain medium in external cavity semiconductor mode-locked lasers is a semiconductor optical amplifier (SOA), and passive and hybrid mode-locked operation are achieved by the introduction of a saturable absorber (SA) in the laser cavity. Pump-probe techniques were used to measure the intracavity absorption dynamics of a SA in an external cavity semiconductor mode-locked laser and the gain dynamics of a SOA for the amplification of diverse pulses. The SOA gain dynamics measurements include the amplification of 750 fs pulses, 6.5 ps pulses, multiwavelength pulses and the intracavity gain dynamics of an external cavity multiwavelength semiconductor mode-locked laser. The experimental results show how the inherent chirp on pulses from external cavity semiconductor mode-locked lasers results in a slow gain depletion without significant fast gain dynamics. In the multiwavelength operation regime of these lasers, the chirp broadens the temporal pulse profile and decreases the temporal beating resulting from the phase correlation among wavelength channels. This results in a slow gain depletion mitigating nonlinearities and gain competition among wavelength channels in the SOA supporting the multiwavelength operation of the laser. Numerical simulations support the experimental results.Ph.D.
Department of Physics
Optics and Photonics
Optics
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Schlatter, Adrian. "Noise properties of high repetition rate mode-locked lasers /." Zürich : ETH, 2006. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16965.
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Delgado-Goroun, Pavel. "Nonlinear carbon structures for mode-locking of fiber lasers." Thesis, KTH, Tillämpad fysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-149682.
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Lee, Shinwook. "HIGH POWER MODE-LOCKED SEMICONDUCTOR LASERS AND THEIR APPLICATIONS." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3195.
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In this dissertation, a novel semiconductor mode-locked oscillator which is an extension of eXtreme Chirped Pulse Amplification (XCPA) is investigated. An eXtreme Chirped Pulse Oscillator (XCPO) implemented with a Theta cavity also based on a semiconductor gain is presented for generating more than 30ns frequency-swept pulses with more than 100pJ of pulse energy and 3.6ps compressed pulses directly from the oscillator. The XCPO shows the two distinct characteristics which are the scalability of the output energy and the mode-locked spectrum with respect to repetition rate. The laser cavity design allows for low repetition rate operation <100MHz. The cavity significantly reduces nonlinear carrier dynamics, integrated self phase modulation (SPM), and fast gain recovery in a Semiconductor optical Amplifier (SOA). Secondly, a functional device, called a Grating Coupled Surface Emitting Laser (GCSEL) is investigated. For the first time, passive and hybrid mode-locking of a GCSEL is achieved by using saturable absorption in the passive section of GCSEL. To verify the present limitation of the GCSEL for passive and hybrid mode-locking, a dispersion matched cavity is explored. In addition, a Grating Coupled surface emitting Semiconductor Optical Amplifier (GCSOA) is also investigated to achieve high energy pulse. An energy extraction experiment for GCSOA using stretched pulses generated from the colliding pulse semiconductor mode-locked laser via a chirped fiber bragg grating, which exploits the XCPA advantages is also demonstrated. Finally, passive optical cavity amplification using an enhancement cavity is presented. In order to achieve the interferometric stability, the Hänsch-Couillaud Method is employed to stabilize the passive optical cavity. The astigmatism-free optical cavity employing an acousto-optic modulator (AOM) is designed and demonstrated. In the passive optical cavity, a 7.2 of amplification factor is achieved with a 50 KHz dumping rate.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Kim, Jimyung. "Quantum Dot Based Mode-Locked Semiconductor Lasers and Applications." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4293.
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In this dissertation, self-assembled InAs/InGaAs quantum dot Fabry-Perot lasers and mode-locked lasers are investigated. The mode-locked lasers investigated include monolithic and curved two-section devices, and colliding pulse mode-locked diode lasers. Ridge waveguide semiconductor lasers have been designed and fabricated by wet etching processes. Electroluminescence of the quantum dot lasers is studied. Cavity length dependent lasing via ground state and/or excited state transitions is observed from quantum dot lasers and the optical gain from both transitions is measured. Stable optical pulse trains via ground and excited state transitions are generated using a grating coupled external cavity with a curved two-section device. Large differences in the applied reverse bias voltage on the saturable absorber are observed for stable mode-locking from the excited and ground state mode-locking regimes. The optical pulses from quantum dot mode-locked lasers are investigated in terms of chirp sign and linear chirp magnitude. Upchirped pulses with large linear chirp magnitude are observed from both ground and excited states. Externally compressed pulse widths from the ground and excited states are 1.2 ps and 970 fs, respectively. Ground state optical pulses from monolithic mode-locked lasers e.g., two-section devices and colliding pulse mode-locked lasers, are also studied. Transformed limited optical pulses (~4.5 ps) are generated from a colliding pulse mode-locked semiconductor laser. The above threshold linewidth enhancement factor of quantum dot Fabry-Perot lasers is measured using the continuous wave injection locking method. A strong spectral dependence of the linewidth enhancement factor is observed around the gain peak. The measured linewidth enhancement factor is highest at the gain peak, but becomes lower 10 nm away from the gain peak. The lowest linewidth enhancement factor is observed on the anti-Stokes side. The spectral dependence of the pulse duration from quantum dot based mode-locked lasers is also observed. Shorter pulses and reduced linear chirp are observed on the anti-Stokes side and externally compressed 660 fs pulses are achieved in this spectral regime. A novel clock recovery technique using passively mode-locked quantum dot lasers is investigated. The clock signal (~4 GHz) is recovered by injecting an interband optical pulse train to the saturable absorber section. The excited state clock signal is recovered through the ground state transition and vice-versa. Asymmetry in the locking bandwidth is observed. The measured locking bandwidth is 10 times wider when the excited state clock signal is recovered from the ground state injection, as compared to recovering a ground state clock signal from excited state injection.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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SAAVEDRA, ADELA ALENCAR. "MODULATION CHARACTERISTICS AND NOISE IN SINGLE MODE SEMICONDUCTOR LASERS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8126@1.
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TELECOMUNICAÇÕES BRASILEIRAS S/APropriedades dinâmicas dos lasers semicondutores monomodo têm sido investigadas utilizando-se diferentes sistemas ópticos de medição. Sistemas ópticos integrados auto- homódino e heteródino foram montados para a medição da modulação em intensidade (IM) e freqüência (FM) e para a obtenção do fator de alargamento da largura de linha (alfa) de três lasers semicondutores de realimentação distribuída (DFB) de seção única. O sistema auto-homódino foi pela primeira vez empregado na obtenção do fator de alargamento da largura de linha. Este sistema mostrou-se mais estável, prático e as medidas apresentam melhor reprodutibilidade que no sistema heteródino, uma vez que é possível obter as características de IM, FM e o parâmetro alfa em uma única medida sem o uso de um outro laser semicondutor como oscilador local. O outro sistema utilizador foi o interferômetro de Mach- Zehnder com detenção balanceada montado com elementos discretos. É possível medir as características de modulação e ruídos dos dispositivos com este interferômetro empregado como discriminador de freqüência. Com este instrumento foi feita a caracterização dinâmica de lasers DFB de seção única, DBR de múltiplas seções e grating assisted codirectional coupler with rear sampled reflector (GCSR) lasers. Foi analisado e pela primeira vez quantificado o efeito de desintonização carrregada em lasers GCSR, pelas medidads de resposta da IM, ruído de freqüência e largura de linha. A realização da caracterização das propriedades dinâmicas de lasers GCSR de larga sintonia é de grande importância, uma vez que muito pouca informação está disponível sobre o assunto pois a estrutura do dispositivo foi desenvolvida recentemente. O lasers GCSR possui quatro seções, uma seção de ganho e três sintonia. Estes dispositivos possuem sintonia quase-contínua de 1520 a 1560nm. Características como ruído de intensidade relativo (RIN), ruído de freqüência, largura de linha, resposta a modulação de amplitude e de freqÜência foram investigadas sob diferentes condições de funcionamento. O comportamento da largura de linha, freeqüência de ressonância, largura de faixa de modulação e varredura em freqüência foi analisado em dez comprimentos de onda espaçados de 4nm dentro da faixa de sintonia. A resposta IM tem características quase constantes sobre a faixa de sintonia e a resposta FM é comparável ou melhor que em lasers com refletor de Bragg distribuído (DBR). O fator de alargamento da largura de linha (alfa) foi obtido de forma inédita pelo uso do interferômetro de Mach-Zehnder com detecção balanceada pela medida das respostas AM e FM, alfa tem seu valor máximo no lado dos comprimentos de onda mais longos e decresce na direção dos comprimentos de onda mais curtos. Foi observado uma melhora em algumas prorpiedades do laser como: redução do ruído de freqüência, largura de linha e aumento da largura de faixa de modulação com a sintonia da seção de fase. Isto é característico da ocorrência do efeito de desintonização carregada (detuned loading effect), o qual geralmente ocorre em lasers DBR. Este efito explica o comportamento observado da largura de linha, largura de faixa de modulação e parâmetro alfa na faixa de sintonia.
Dynamic properties of single mode semiconductor lasers have been investigated using different optical set-ups. Intergrated optical self-homodyne and heterodyne systems were mounted to measure the intensity (IM) and frequency (FM) modulation responses and to obtain the linewidth enhancement factor (a) of three single-section distributed feedback lasers (DFB). The self-homodyne interferometric system was used for the first time to obtain the linewidth enhancement factor. This system is more stable, reproducible and practical than the heterodyne set-up, since it is possible to obtain IM, FM characteristics and a parameter in one measurement without using another semiconductor lase as a local oscillator. The other system used was the Mach-Zehnder interferometer with balanced detection mounted with discrete optical elements. This instrument works as a frequency discriminator, therefore, it is possible to anlyse the modulation and noise properties of semiconductor lasers with one or more sections. Single section DFB lasers, multi-section DBR and grating assisted condirectional coupler with rear sampled reflector (GCSR) lasers were characterised using the interferometer. Measuring the IM response, frequency noise and linewidth of GCSR lasers it was possible to study the detuned loading effect in these devices. This effects was quantified for the first time in this work. The dynamic characterisation of widely tunable GCSR lasers is really relevant, once very little information is available about these devices and their structure was developed recently. The GCSR laser has four sections, one gain section and three tuning sections. These devices have quasi-continous tuning range from 1520 to 1560 nm. The relative intensity noise (RIN), frequency noise and linewidth characteristics, amplitude modulation (AM) and FM responses were measured at ten different wavelength spaced by 4 nm on the tuning range. The AM response hag quasi-constant characteristics on the tuning range and the FM response is comparable or better than on ordinary distributed Bragg reflector lasers (DBR). A new technique for a parameter extraction was developed measuring AM and FM responses using a Mach-Zehnder interferometer with balanced detection. The calculated a aparameter has a maximum value in the long wavelength side and decreases in the direction of the short wavelength side. An improvement of some laser properties like frequency noise, linewidth and modulation bandwidth with the phase tuning was observed. These are characteristics of the detuned loading effect, which usually occurs in DBR lasers. This effect explains the linewidth, bandwidth and a parameter behaviour on the tuning range.
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Avramopoulos, Hercules. "Phase effects in dispersion compensated passively mode-locked lasers." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47342.
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Birge, Jonathan R. (Jonathan Richards). "Methods for engineering sub-two-cycle mode-locked lasers." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53192.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 159-166).
We begin by presenting a method to efficiently solve for the steady-state solution of a nonlinear cavity, suitable for simulating a solid-state femtosecond laser. The algorithm directly solves the periodic boundary value problem by using a preconditioned Krylov-Newton shooting solver. The method can be applied to the design and study of mode-locked lasers, as well as the modeling of field enhancement cavities, such as those used in high harmonic generation. In contrast to the standard approach of dynamic simulation, which converges linearly, our algorithm converges quadratically to the stable solution, typically converging two to three orders of magnitude faster than the standard approach. The second major theme is the control of dispersion in mode-locked lasers. The predominant way to design dispersion compensating optics in the past has been a consideration of the integrated net group delay dispersion (GDD). We propose and implement an alternative spectral quantity based on the energy contained in phase distortions, which we term the Phase Distortion Ratio (PDR). Dispersion compensating mirrors optimized with respect to PDR generally perform significantly better than those where GDD is optimized. We demonstrate this in the design of a dispersion compensating mirror pair capable of compressing single-single pulses. In the final section, we deal with the unique challenges inherent to measuring sub-two-cycle pulses reliably and accurately. We have recently developed a technique, Two-Dimensional spectral Shearing Interferometry (2DSI), based on spectral shearing, which requires no calibration and does not disperse the pulse being measured.
(cont.) Our method intuitively encodes spectral group delay in a slowly changing fringe in a two-dimensional interferogram. This maximizes use of spectrometer resolution, allowing for complex phase spectra to be measured with high accuracy over extremely large bandwidths, potentially exceeding an octave. We believe that 2DSI is a uniquely cost effective and efficient method for accurately and reliably measuring few- and even single-cycle pulses. While the method is relatively recent, it is well tested and has been successfully demonstrated on several different lasers in two different groups, including one producing 4.9 fs pulses.
by Jonathan R. Birge.
Ph.D.
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Kbashi, Hani. "Vector optical rogue waves in mode-locked fibre lasers." Thesis, Aston University, 2018. http://publications.aston.ac.uk/37771/.
Full textAbstract:
The project consists of an experimental characterisation of optical vector rogue wave (RW) events by using three different testbed fibre laser setups. The first testbed is a long cavity fibre laser (615 m). Here, we have demonstrated for the first time, a new type of vector resonance multimode instability that inherits some features of modulation and multimode instability. This instability leads to emerging different pulse laser regimes from longitudinal modes synchronization to different types of optical RW events. Using the same testbed fibre laser, we have also shown experimentally for the first time fibre twist-based chiral symmetry breaking. This leads to versatile laser dynamics tuneable from a periodic pulse similar mode-locked regime to chaotic oscillations which are revealed as a mechanism for the emergence of RW events. The observed optical RW events have been classified as fast optical RWs or slow optical RWs depending on the autocorrelation function of the experimental data. The classified optical RWs have been studied by collecting experimental data of a 19x19 grid of polarization positions through tuning both intra-cavity and pump polarization controllers. The second testbed is a passively mode-locked fibre laser. Using this system, the control, appearance and disappearance of the soliton rain flow were demonstrated for the first time using a low range of pump power. Harmonics soliton rain, soliton fission and soliton-soliton interactions leading to the emergence of optical RWs have also been demonstrated in this experiment at a different pump power and intra-cavity birefringence. High harmonic (902 MHz) mode-locked fibre laser based on acoustic-optic effect has been realized in the same laser experiment. In the third laser testbed experiment with, a stretched mode-locked fibre laser, vector bright-dark optical RWs were observed experimentally for the first time. These bright-dark RWs have formed in the laser cavity due to modulation instability at close pump power threshold or due to the polarization instability (incoherent coupling) at higher pump power.
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Hajjiah, Ali T. "Design and Analysis of Whispering Gallery Mode Semiconductor Lasers." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26136.
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Significant technical barriers currently prevent the wide spread adoption of WGM lasers as building blocks in large-scale photonic integrated circuits. The first challenge is to reduce the electrical power consumption at desirable levels of light output power. The second target is to obtain directional light emission without sacrificing other laser performance metrics. The best opportunity for success lies in the pursuit of small micro-Pillar lasers with spiral-geometry cavities. Process technology has been demonstrated for making high-performance WGM lasers including a refined ICP etching process for fabricating micro-Pillar cavities with sidewall roughness less than 10 nm and a new hydrogenation based approach to achieving current blocking that is compatible with all other processing steps and robust in comparison with earlier reports. A comprehensive photo-mask has been designed that enables investigation of the interplay between device geometry and WGM laser performance. Emphasis has been placed on enabling experiments to determining the impact of diffraction and scattering losses, current and carrier confinement, and surface recombination on electrical/optical device characteristics. In addition, a methodology has been developed for separating out process optimization work from the task of identifying the best means for directional light out-coupling. Our device fabrication methods can be proven on WGM lasers with pure cylindrical symmetry, hence results from these experiments should be independent of any specific light output coupling scheme. Particular attention has been paid to the fact that device geometries that give the best performance for purely symmetrical cavities may not yield the highest level of light emission from the spiral output notch. Such considerations seem to be missing from much of the earlier work reported in the literature. Finally, our processing techniques and device designs have resulted in individual WGM lasers that outperform those made by competitors. These devices have been incorporated into multi-element, coupled-cavity optical circuits thereby laying the groundwork for construction of digital photonic gates that execute AND, OR, and NOT logic functions.Ph. D.
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Virte, Martin. "Two-mode dynamics and switching in quantum dot lasers." Thesis, Supélec, 2014. http://www.theses.fr/2014SUPL0020/document.
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Dans cette thèse, j'étudie la dynamique non linéaire résultant d’une compétition entre deux modes dans des systèmes lasers à boites quantiques.D’abord, je considère le cas de la compétition entre deux modes de polarisation apparaissant dans les diodes laser nanostructurées à cavité verticale et émettant par la surface (VCSELs). Il est connu que ces composants peuvent avoir une polarisation instable menant à des dynamiques riches. Récemment, un surprenant saut de mode entre deux états polarisés elliptiquement a été récemment découvert dans les VCSELs à boites quantiques. Ce comportement montre des propriétés intrigantes qui nécessitent une interprétation alternative. Dans cette thèse, je montre que ce comportement dynamique peut-être reproduit en utilisant le modèle spin-flip (SFM). En particulier je démontre et confirme expérimentalement que les sauts de modes sont en réalité des fluctuations chaotiques de faible dimension : un chaos en polarisation. Je démontre ensuite la pertinence de la dynamique chaotique observée pour les applications exploitant le chaos optique, en réalisant un générateur de nombres aléatoires à grande vitesse basé sur le chaos en polarisation.Deuxièmement, j'étudie les effet d'une rétroaction optique à délai sur les lasers à boites quantiques émettant simultanément depuis l'état fondamental et le premier état excité. Je clarifie l'impact the cette rétroaction optique ainsi que les mécanismes et bifurcations correspondantes. Je montre théoriquement qu'une rétroaction optique favorise globalement l'émission par l'état fondamental, mais aussi qu'un tel montage peut être utilisé pour commuter entre ces deux modes d'émission lorsque l'on change le taux ou le délai de la rétroaction. Enfin, je confirme ces observations expérimentalement, en rapportant des commutations entre l'état fondamental et l'état excitéIn this thesis, I study the nonlinear dynamics induced by the competition between two modes in quantum dot laser systems.First, I focus on the competition between polarization modes that takes place in quantum dot vertical-cavity surface-emitting lasers (VCSELs). It is well-known that these devices can exhibit polarization instabilities leading to rich dynamical evolution. Recently, a new peculiar random-like hopping between two non-orthogonal elliptically polarized states has been highlighted in QD VCSELs. This behavior shows intriguing features which clearly call for a different interpretation. In this thesis, I show that the dynamical behavior reported experimentally can accurately be reproduced within the spin-flip model (SFM) framework. In particular, I demonstrate and confirm experimentally that the peculiar random-like hoppings are in fact deterministic low-dimensional chaotic fluctuations, i.e. ``Polarization Chaos''. I then make a proof-of-concept demonstration of a high-speed random bit generator based on polarization chaos, hence demonstrating that the chaotic dynamics uncovered is relevant for optical chaos-based applications.Secondly, I investigate the effects of an external optical feedback on quantum dot lasers emitting simultaneously from the ground and the excited states. I bring new light on the impact of optical feedback and the corresponding mechanisms and bifurcations. I highlight theoretically that optical feedback globally favors the ground state emission, but also that it can be used to switch from one mode to the other when changing the feedback rate and/or the time-delay. In addition, I experimentally report switching between the ground and excited states when varying the external cavity length at the micrometer scale, which supports the theoretical predictions
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Kelleher, Edmund J. R. "Advancements in mode-locked fibre lasers and fibre supercontinua." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9584.
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The temporal characteristics and the spectral content of light can be manipulated and modified by harnessing linear and nonlinear interactions with a dielectric medium. Optical fibres provide an environment in which the tight confinement of light over long distances allows the efficient exploitation of weak nonlinear effects. This has facilitated the rapid development of high-power fibre laser sources across a broad spectrum of wavelengths, with a diverse range of temporal formats, that have established a position of dominance in the global laser market. However, demand for increasingly flexible light sources is driving research towards novel technologies and an improved understanding of the physical mechanisms and limitations of existing approaches. This thesis reports a series of experiments exploring two topical areas of ongoing research in the field of nonlinear fibre optics: mode-locked fibre lasers and fibre-based supercontinuum light sources. Firstly, integration of novel nano-materials with existing and emerging fibre-based gain media allows the demonstration of ultrafast mode-locked laser sources across the near-infrared in a conceptually simple, robust, and compact scheme. Extension to important regions of the visible is demonstrated using nonlinear conversion. Scaling of pulse energies in mode-locked lasers can be achieved by operating with purely positive dispersion for the generation of chirped pulses. It is shown unequivocally, through a direct measurement, that the pulses generated in ultra-longmode-locked lasers can exist as highly-chirped dissipative soliton solutions of the cubic (and cubic-quintic) Ginzburg Landau equation. The development of a numerical model provides a framework for the interpretation of experimental observations and exposes unique evolution dynamics in extreme parameter ranges. However, the practical limitations of the approach are revealed and alternative routes towards achieving higher-energy are proposed. Finally, an experimental and numerical study of the dependence of continuous-wave pumped supercontinua on the coherence properties of the pump source shows an optimum exists that can be expressed as a function of the modulation instability period. A new and simplified model representing the temporal fluctuations expressed by continuous wave lasers is proposed for use in simulations of supercontinua evolving from noise. The implications of the experiments described in this thesis are summarised within the broader context of a continued research effort.
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Oliveira, Luiz Felipe Lorenzoni de. "Mode-locking de um laser de corante pulsado bombeado por lâmpada." [s.n.], 1994. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277459.
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Orientador: Carlos Henrique de Brito CruzDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
Made available in DSpace on 2018-07-19T15:08:22Z (GMT). No. of bitstreams: 1 Oliveira_LuizFelipeLorenzonide_M.pdf: 2852272 bytes, checksum: d2b849e1203ded5e535eea8f5923eaff (MD5) Previous issue date: 1994
Resumo: Neste trabalho descreve - se a teoria envolvida e os procedimentos experimentais que foram efetuados para a construção de um Lazer de Corante do tipo CPM bombeado por lâmpada flash com compensação da dispersão de velocidade de grupo e balanceamento da auto modulação de fase a partir de um Laser de Corante comercial marca Chromatix, modelo CMX - 4. Foram obtidos pulsos em 596,5 nm com durações temporais FWHM de 896 fs com 250 kW de potência de pico e com largura espectral de 1,5 nm
Abstract: In this work, we describe the construction of a CPM Dye Laser Flashlamp-Pumped with group velocity dispersion compensation and self phase modulation balancing, based on a comercial Dye Laser, Chromatrix, CMX-4 model. We obtain pulses at 596.5 nm with time duration FWHM of 896 fs with 250KW of peak power and spectral line width of 1.5nm
Mestrado
Física
Mestre em Física
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Yu, Nu. "Coupling of a semiconductor laser to a single-mode fiber." Full text open access at:, 1987. http://content.ohsu.edu/u?/etd,135.
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Hsu, Kevin. "Stochastic mode-locking theory and short pulse generation by active mode-locking of external-cavity semiconductor lasers." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/14990.
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O'Hagan, Seamus. "Multi-mode absorption spectroscopy for multi-species and multi-parameter sensing." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:6f422683-7c50-47dd-8824-56b4b4ea941d.
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The extension of Multi-mode Absorption Spectroscopy (MUMAS) to the infra-red spectral region for multi-species gas sensing is reported. A computationally efficient, theoretical model for analysis of MUMAS spectra is presented that avoids approximations used in previous work and treats arbitrary and time-dependent spectral intensity envelopes, thus facilitating the use of commercially available Interband Cascade Lasers (ICLs) and Quantum Cascade Lasers (QCLs). The first use of an ICL for MUMAS is reported using a multi-mode device operating at 3.7 μm to detect CH4 transitions over a range of 30 nm. Mode-linewidths are measured using the pressure-dependent widths of an isolated absorption feature in HCl. Multi- species sensing is demonstrated by measurement of partial pressures of CH4, C2H2 and H2CO in a low-pressure mixture with uncertainties of around 10%. Detection of CH4 in N2 at 1 bar is demonstrated using a shorter-cavity ICL to resolve spectral features in pressure-broadened and congested spectra. The first use of a QCL for MUMAS is reported using a commercially available device operating at 5.3 μm to detect multiple absorption transitions of NO at a partial pressure of 2.79 μbar in N2 buffer gas. The revised model is shown to enable good fits to MUMAS data by accounting for the time-variation of the spectral intensity profile during frequency scanning. Individual mode-linewidths are derived from fits to pressure- dependent MUMAS spectra and features from background interferences due to H2O in laboratory air are distinguished from those of the target species, NO. Data obtained at scan rates up to 10 kHz demonstrate the potential for achieving short measurement times. The development of a balanced ratiometric detection scheme for MUMAS with commercially available multi-mode lasers operating at 1.5 μm is reported for simultaneous detection of CO and CO2 showing improved SNR performance over previous direct transmission methods and suitability for a compact field-employable instrument. In addition, MUMAS spectra of CO2 are used to derive gas temperatures with an uncertainty of 3.2% in the range 300 - 700 K.
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Rosales, Ricardo. "InAs/InP quantum dash mode locked lasers for optical communications." Phd thesis, Institut National des Télécommunications, 2012. http://tel.archives-ouvertes.fr/tel-00923176.
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This PhD thesis focuses on the study of mode locked laser diodes based on novel optimized InAs Quantum Dash structures grown on InP substrates. It covers several important modelling aspects, the clean room processing of single and two section shallow ridge waveguide lasers, characterization of the fabricated devices and the evaluation of their performance in different application scenarios. Systematic characterization experiments and subsequent analyses have allowed to gain a much deeper comprehension of the physical mechanisms related to the mode locking regime in these devices, thus far not completely understood. This has allowed to better control most of the main physical phenomena limiting device performance, resulting in first demonstrations of record peak power, sub-picosecond pulse, low radio frequency linewidth and high repetition frequency mode locked lasers grown on InP substrates, opening the way to a vast number of potential applications in the 1.55 µm telecommunication window
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Bogan, Christina [Verfasser]. "Stabilized High Power Lasers and Spatial Mode Conversion / Christina Bogan." München : Verlag Dr. Hut, 2013. http://d-nb.info/1033041505/34.
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Norris, Gavin J. R. "Whispering Gallery mode lasers for the mid-infrared spectral range." Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441779.
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Hill, C. A. "Mode control and tunability in Rf-excited CO2̲ waveguide lasers." Thesis, University of Hull, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381878.
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Tandoi, Giuseppe. "Monolithic high power mode locked GaAs/AlGaAs quantum well lasers." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2721/.
Full textAbstract:
In this thesis, approaches for increasing the output power in monolithically integrated semiconductor mode locked (ML) lasers were investigated. The wavelength range considered is the range of operation of low temperature grown GaAs photomixers, devices commonly used for THz generation. In particular, two GaAs/AlGaAs quantum well laser epistructures (operating at 830 nm and 795 nm) were considered, both with reduced optical confinement and elongated vertical optical mode size. In this work, such laser epistructures, commonly used by high power semiconductor laser manufacturers, were successfully employed, for the first time, for producing passively ML devices. Improved average powers (up to 48 mW) under ML operation were demonstrated, around ten times higher than values previously reported in monolithic GaAs/AlGaAs ML lasers. In continuous wave operation, the output power was limited by the catastrophic damage of the laser facets at around 50 mW. For this reason, facet passivation techniques were investigated, allowing for powers up to 124 mW to be achieved. In ML regime, the output power was instead limited by the catastrophic damage of the reverse biased section of the laser. This failure mechanism was investigated and explained considering thermal effects on the reverse biased section. Such effects limited the output power to around 27 mW in 830 nm devices, which was then improved by 70% in 795 nm devices with a 70% larger optical mode area. The larger mode size, combined to a small duty-cycle laser geometry, enabled a record peak power of 9.8 W to be achieved at 6.83 GHz. This particular repetition rate was specifically designed for coherent population trapping experiments in 87Rb vapors. Sub-picosecond transform limited pulses were achieved in both the laser materials considered, with a minimum duration of 0.43 ps at 126 GHz. With the values of peak power achieved, the developed devices may also be directly used for two-photon microscopy applications.