Дисертації з теми "Raman fiber lasers"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-44 дисертацій для дослідження на тему "Raman fiber lasers".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
Gapontsev, Denis Valentinovitch. "Fiber Raman lasers and amplifiers and their applications." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322403.
Повний текст джерелаBerberoglu, Halil. "Numerical Simulations On Stimulated Raman Scattering For Fiber Raman Amplifiers And Lasers Using Spectral Methods." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/3/12608986/index.pdf.
Повний текст джерелаknowledge in this thesis. Numerical results demonstrate that in a few iterations great accuracy is obtained using fewer grid points.
Zhu, Gongwen. "Q-switched and Mode-locked Mid-IR Fiber Lasers." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/578593.
Повний текст джерелаEl, bassri Farid. "Sources lasers déclenchées nanosecondes : Applications à la spectroscopie Raman cohérente sous champ électrique." Thesis, Limoges, 2014. http://www.theses.fr/2014LIMO0060/document.
Повний текст джерелаThanks to their compactness, robustness and low cost, pulsed nanosecond microlasers are particularly attractive sources for different detection and analysis systems, particularly flow cytometers or devices for CARS (Coherent Anti Raman Stokes Scattering) spectroscopy. However, these applications require reduced time jitter and increased repetition rate. The first part of this thesis proposes novel solutions to achieve the required performance from passively Q-switched microlasers, which are based on an hybrid coupled-cavity and intensitymodulated pump wave. A repetition rate greater than 30 kHz with jitter remaining lower than 200 ns is reached. Pulsed fiber microlasers operating by gain switching are also studied, showing that pulses with low timing jitter, at a repetition rate of more than 2 MHz can be obtained. The last part is devoted to the development and the implementation of a new system of CARS spectroscopy assisted by a high-voltage electrical stimulation. This device, based on an amplified microlaser, allows to substract the non-resonant background noise in the measurements. Thus, a fine spectroscopic analysis of the response of different environments of interest in continuous or pulsed field can be achieved. It may lead to a new method for field microdosimetry. Various applications, including granulometry at the micro or nanometric scale and the identification of markers for biology, are shown
Nishizawa, Norihiko, Youta Ito та Toshio Goto. "0.78-0.90-μm wavelength-tunable femtosecond soliton pulse generation using photonic crystal fiber". IEEE, 2002. http://hdl.handle.net/2237/6769.
Повний текст джерелаBenoit, Aurélien. "Sources laser fibrées hybrides de haute puissance : Amplification et conversion de fréquences." Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0024/document.
Повний текст джерелаHigh-power fiber lasers adress an increasing number of applications since ten years. In the frame of a CIFRE contract between the company Eolite Systems and Xlim (joint laboratory between CNRS and the University of Limoges), the goal of this PhD project was to develop the technological blocs to achieve all-fibre high-power lasers emiting out of the conventional spectral band covered by existing lasers.Modal instabilities in large mode area (LMA) fibers are currently the main limitation of the fiber lasers power scaling. We have experimentally demonstrated the relevance of inner cladding aperiodic structures to efficiently delocalize higher order modes outside the gain region. A systematic study of passive fibers based on such structures has shown the single propagation of the fundamental mode over a wide wavelength range from 1 to 2 µm for dimension of core up to 85 µm. This effective mode delocalization even extends up to a core dimension of 140 µm at a 2 µm wavelength.The combination of high power picosecond fiber laser with an average power of 22.7 W and a hydrogen-filled inhibited coupling Kagome fiber allowed us to generate two Raman combs over five frequency octaves from 321 nm to 12.5 µm. These two combs are controlled by the laser pump polarization and generated an average power of 10.1 W displayed over 70 laser lines for circular pump polarization and 8.6 W over 30 lines for linear polarization. Some laser lines within these combs have been generated for the first time from high-power fiber source in the mid-infrared range. We have also demonstrated the generation of high-power line by optimizing the first vibrational Stokes at 1.8 µm with an average power of 9.3 W and a quantum efficiency of the frequency conversion stage close to 80%
Louot, Christophe. "Sources de supercontinuum pour la microspectroscopie Raman cohérente large-bande." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0015/document.
Повний текст джерелаCoherent Raman microspectroscopy (CARS) is an optical method used to identify molecular bonds in a sample in order to analyze and determine its complete composition. It requires the simultaneous excitation of the sample by two waves (the pump wave and the Stokes wave) in order to induce resonant vibration of the bond to be detected. For multiple bonds analysis (broadband coherent Raman microspectroscopy our Multiplex-CARS), the monochromatic Stokes wave must be replaced by a broadband beam (supercontinuum). The aim of this thesis was to design supercontinuum sources optimized for Multiplex-CARS application, in particular in terms of spectral bandwidth and spectral power density. Supercontinuum generation was investigated in three different optical fibers: (i) a microstructured single mode fiber with a large Yb doped core in which the input beam was re-amplified all along its propagation; (ii) a conventional singlemode fiber pumped in the normal dispersion regime in which spectral broadening was achieved by means of Raman gain saturation; (iii) a conventional graded-index multimode fiber in which the beam spectrally broadened by Raman gain saturation at very high power also experienced spatial self-cleaning by Kerr effect, resulting in a high brillance output beam with an,intensity profile close to that of the fundamental mode. A complete spectrotemporal study is achieved for each of these three sources
Nishizawa, Norihiko, and Toshio Goto. "Widely wavelength-tunable ultrashort pulse generation using polarization maintaining optical fibers." IEEE, 2001. http://hdl.handle.net/2237/6864.
Повний текст джерелаNishizawa, Norihiko, and Toshio Goto. "Compact system of wavelength-tunable femtosecond soliton pulse generation using optical fibers." IEEE, 1999. http://hdl.handle.net/2237/6767.
Повний текст джерелаNishizawa, Norihiko, Ryuji Okamura, and Toshio Goto. "Simultaneous generation of wavelength tunable two-colored femtosecond soliton pulses using optical fibers." IEEE, 1999. http://hdl.handle.net/2237/6771.
Повний текст джерелаAlsaleh, Magda. "Application de la méthode des coordonnées collectives à l'analyse de la dynamique des lasers à fibre à modes bloqués." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS091/document.
Повний текст джерелаMode-locked fiber laser are among the few systems that allow to achieve a variety of elaborate optical functions, by means of few optical components. The use of dispersion management brings to this type of lasers a variety of behaviors, which is so rich that the complete mapping and detailed analysis of the stable states becomes impractical when conventional tools based on the intra-cavity field propagation equations, are used. In this thesis we show that the addition of the technique ofcollective coordinates to the conventional theoretical tools, allows to solve at least in part the problem of complexity and diversity of the stable states of the cavity. In particular, we propose the DCCA (dynamical collective coordinate approach), as a theoretical tool to achieve substantial performance gains in search and characterization of stable states of the laser. Furthermore, the use of the collective coordinated approach allows us to highlight major effects induced by certain phenomena that were until now largely underestimated. In particular, we highlight major changes in the respective areas ofthe different stable states of the laser, which occur when changing the width of the band-pass filter BPF. Furthermore, considering a cavity where the spectral width of the light field (3.12 THz) is an order of magnitude smaller than the bandwidth of the Raman gain, we highlight remarkable effects of Raman scattering on hysteresis phenomena
Chafer, Matthieu. "Sources lasers innovantes à base de micro-capsules photoniques et par nano-structuration de milieux gazeux." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0042.
Повний текст джерелаSince their advent, hollow-core photonic crystal fibers have proved to be highly efficient for frequency conversion, especially via by playing with stimulated Raman scattering. Within the frame work of a CIFRE contract between the firm GLOphotonics and the Xlim research institute, this thesis project has consisted in developing these fibers to enhance their optical performances, in order to target two different field of applications: an industrial one to offer a a compact multi-line laser in the visible and UV and a second more fundamental one to realize a optical wave synthesizer. The amelioration of these performances relies on the exacerbation of the inhibition of the coupling between the air core mode and the silica cladding modes. Two types of micro-structures have been explored, a Kagomé and a tubular lattice. Several fibers have been fabricated demonstrating record performances on all a wavelength range (8.5 dB/km at 1 µm, 7.7 dB/km at 750 nm, 13.8 dB/km at 549 nm, and around 70 dB/km at 355 nm). Concerning the functionalization of the fibers, photonic micro-cells have been designed and realized enabling to overcome the problem the permeability of silica to gas (conversion stability over 12 months) and demonstrate a conversion to 26 lines in the visible. An industrial product coined CombLas has been made and used for flow cytometry in order to study the influence of the repetition rate of the pump laser. This product has also been extended to the UV range with 24 lines generated between 225-400 nm. Also, more fundamental research has been realized consisting in developing an optical wave synthesizer based on Raman generation in hollow core fibres where a new dynamic has been observed demonstrating the trapping of hydrogen molecules by an auto-assembled optical lattice of ultra-deep and nano-metric potential wells. This configuration has enabled to generate a Lamb-Dicke regime of stimulated Raman scattering. Sub-Doppler signatures usually found in cold atoms have been measured with linewidths narrower than 5 orders of magnitude than what is predicted in the literature. Finally, this linewidth has been optmised of an order of magnitude by plaing on the length of the fiber and the pressure of hydrogen
Ji, Junhua. "Cladding-pumped Raman fibre laser sources." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/186035/.
Повний текст джерелаAlcon, Camas Mercedes. "Applications of ultralong Raman fibre lasers in photonics." Thesis, Aston University, 2011. http://publications.aston.ac.uk/15795/.
Повний текст джерелаZhou, Renjie. "Developments of Narrow-Linewidth Q-switched Fiber Laser, 1480 nm Raman Fiber Laser, and Free Space Fiber Amplifier." Thesis, The University of Arizona, 2011. http://hdl.handle.net/10150/202931.
Повний текст джерелаTiwari, Vidhu Shekhar. "DEVELOPMENT OF FIBER OPTIC SENSOR BASED ON LASER RAMAN SPECTROSCOPY." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07082008-143038/.
Повний текст джерелаDalloz, Nicolas. "Formation du spectre optique dans les lasers Raman à fibre." Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2011. http://tel.archives-ouvertes.fr/tel-00628627.
Повний текст джерелаTan, Mingming. "Raman fibre laser based amplification in coherent transmission systems." Thesis, Aston University, 2016. http://publications.aston.ac.uk/28899/.
Повний текст джерелаTarasov, Nikita. "Temporal and spatio-temporal regimes of generation of Raman fibre lasers." Thesis, Aston University, 2016. http://publications.aston.ac.uk/28851/.
Повний текст джерелаDoutte, Anne. "Étude expérimentale et théorique de la dynamique des lasers Raman à fibre optique." Lille 1, 2005. http://www.theses.fr/2005LIL10158.
Повний текст джерелаDixon, Nicholas Michael. "Raman microscopy of laser damaged dielectric films and optical fibre inclusions." Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277399.
Повний текст джерелаPaipetis, Alkiviadis. "A study of carbon fibre/epoxy interface using remote laser Raman microscopy." Thesis, Queen Mary, University of London, 1997. http://qmro.qmul.ac.uk/xmlui/handle/123456789/25538.
Повний текст джерелаRosa, Paweł. "Quasi-lossless data transmission with ultra-long Raman fibre laser based amplification." Thesis, Aston University, 2014. http://publications.aston.ac.uk/22442/.
Повний текст джерелаDupee, James David. "On-line crystallinity and temperature measurements of nylon 6,6 using a remote laser Raman probe." Thesis, Queen Mary, University of London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287935.
Повний текст джерелаFortin, Vincent. "Développement de lasers à fibre basés sur la conversion Raman émettant entre 2 et 4 um." Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25368.
Повний текст джерелаFiber lasers are robust, reliable and efficient laser sources that also offer an unrivaled beam quality, but most are limited to the specific spectral bands where rare-earth electronic transitions exist. Raman fiber lasers, however, can be operated on virtually any emission wavelength and can be used to bridge the gap between these rare-earth emission bands. Therefore, they could be designed to emit on any wavelength between 2 and 4 m, which would find many applications in the medical, military and spectroscopic fields. Standard silicate fibers cannot be considered for this purpose, due to their limited transparency at wavelengths over 2.2 m. Fluoride and chalcogenide glass fibers are much better suited for this task even though they bring new technical challenges. During our Ph.D. project, Raman lasers based on both fluorozirconate and arsenic trisulphide (As2S3) glass fibers were studied. In fact, we reported the very first experimental Raman cavities based on these materials. First, fluorozirconate Raman cavities emitting around 2.2 m and pumped by a Tm:silica fiber laser were assembled and perfected. Based on an architecture where the Raman and pump laser cavities are nested, we have achieved high output power levels, up to a few watts. We have also demonstrated As2S3 Raman cavities operating directly in the mid-infrared, at 3.34 m. They were pumped by an in-house made erbium doped fluoride fiber laser at 3 m. Due to the high Raman gain of chalcogenide glasses, only a few meters of fiber were required. The behavior of these laser sources was also investigated numerically to find their optimal operating parameters and to identify their limits. The results obtained prove that fiber lasers are well suited for generating a wide range of wavelengths between 2 and 4 um.
Huneault, Mathieu. "Investigation numérique de l'instabilité Raman dans les lasers à fibre optique dopée à l'ytterbium en régime continu de haute puissance." Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/34745.
Повний текст джерелаContinuous high-power ytterbium-doped fiber lasers have an increasing market share formetal processing applications. Despite their widespread use, these lasers still suffer a ma-jor problem. At high power, stimulated Raman scattering shifts the power from the main emission wavelength around 1070 nm to the first Raman Stokes sideband around 1120 nm. This process is called Raman instability. The shifted power becomes useless and can even be dangerous for both the laser system and its users. Previous experimental and theoretical analyses have failed to provide clear explanations on the link between the Raman instability and the parameters of the ytterbium-doped optical fiber and the fiber Bragg gratings forming the laser cavity. The goal of this master’s degree project was to develop a simulation model for continuous high-power ytterbium-doped fiber lasers in order to identify and understand how the parameters of the laser cavity affect the Raman instability and to find cavity configurations that reduce it. This master’s thesis presents the two simulation models developed during this project. The first model considers unidirectionnal propagation of the laser signal while the second one considers bidirectionnal propagation. The latter is thus a more realistic model of such lasers.The typical simulated setup is made of a double-clad ytterbium-doped fiber with a large mode area, a high reflectivity Bragg grating and a low reflectivity Bragg grating that isused as output coupler. The simulations allowed to identify five cavity parameters having an impact on the Raman instability. A low average power, a short gain fiber, a counter-propagation pumping setup as well as a low reflectivity and a large reflective bandwidth for the fiber Bragg grating used as the output coupler help minimizing the Raman instability.The optimisation of these parameters creates a laser cavity with an extremely low power shift to the Raman Stokes sideband. The low Raman instability seems to be caused by a lower intra-cavity power, a shorter propagation distance and fast power modulations in thesignal. Incorporating a filter in the cavity, using a nonlinear reflector as output coupler or using a setup that includes a low-power master oscillator in combination with a high-power amplifier have also been simulated and show a reduction of the Raman instability.
Ziemieńczuk, Marta [Verfasser], and Philip [Akademischer Betreuer] Russell. "Coherent Gas-Laser Interactions via Stimulated Raman Scattering in Hollow-Core Photonic Crystal Fibers / Marta Ziemieńczuk. Betreuer: Philip Russell." Erlangen : Universitätsbibliothek der Universität Erlangen-Nürnberg, 2012. http://d-nb.info/1023597489/34.
Повний текст джерелаAbdolghader, Pedram. "Coherent Nonlinear Raman Microscopy and the Applications of Deep Learning & Pattern Recognition Methods to the Extraction of Quantitative Information." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42677.
Повний текст джерелаAyoub, Anas. "Sources laser ultrarapides performantes dans le moyen IR et le Tz." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR044.
Повний текст джерелаThe atome probe tomography is an instrument for analyzing matter in three dimensions with atomic resolution. This instrument relies on the effect of an electric field generated at the end of a sample cut into the shape of a nanoscale needle to evaporate the surface atoms which are collected by a two-dimensional detector. The measurement of the time of flight of the ions whose evaporation is triggered by an electrical or optical pulse makes it possible to measure the chemical composition in addition to the 3D localization of the atoms. In current atome probes, atomic evaporation is triggered by a high-speed laser emitting in the UV. However, the interaction of UV light with matter induces thermal heating which limits the mass resolution of the instrument and prevents its use for the analysis of fragile materials such as biocompatible components. This thesis work aims to study solutions to promote rapid evaporation while inhibiting unwanted thermal effects of the laser in atome probe. Our approach consists in exploiting ultrashort pulses in the mid-infrared or THz domain due to their high ponderomotive energy associated with low photon energy. This manuscript reports on the development of a bench for the generation and characterization of intense THz pulses. Coupling these radiations with a negatively polarized metallic nanotip has made it possible to characterize the near field induced at the surface of the nanotip, which is strongly modified by the antenna effect. The second part reports on the development of an ultra-fast laser source tunable in the mid-infrared around 3 mm using fluoride glass fibers
Carrier, Julien. "Écriture de réseaux de Bragg par laser femtoseconde à 400 NM." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29736/29736.pdf.
Повний текст джерелаDoutre, Florent. "Sources d'impulsions brèves basées sur des procédés de découpe non linéaires au sein d'une fibre optique ; nouvelles sources déclenchées à cavités couplées." Phd thesis, Université de Limoges, 2010. http://tel.archives-ouvertes.fr/tel-00682880.
Повний текст джерелаSteinberg, David. "Laser Raman à fibra operando na banda O em regime de acoplamento passivo de modos utilizando nanotubos de carbono como absorvedores saturáveis." Universidade Presbiteriana Mackenzie, 2015. http://tede.mackenzie.br/jspui/handle/tede/1531.
Повний текст джерелаFundo Mackenzie de Pesquisa
In this thesis, for the first time we present results of passively-mode-locking O-band Raman fiber laser operating at 1310 nm by using carbon nanotubes as saturable absorber. The first results were obtained for an experimental setup based on single mode fiber (SMF) with laser operating near zero fiber dispersion at 1310 nm at anomalous regime. In this same configuration, a study of pulse duration shortening in terms of intracavity dispersion management with dispersion shifted fiber lengths (DSF) was performed. Replacing the SMF by a highly doped germanium fiber as gain medium of Raman fiber laser, operation was shifted to normal dispersion regime and passive mode-locking was also generated. In this laser, a study of pulse duration shortening in terms of gain medium length reduction was performed and the picosecond pulse regime of the laser could be estimated. We also present a brief comparison between the two dispersion regimes of the Raman fiber laser and passive mode-locking results obtained with different diameters of carbon nanotubes as saturable absorbers.
Nesta tese, apresentamos pela primeira vez resultados do acoplamento passivo de modos em um laser Raman à fibra operando em 1310 nm na banda O, utilizando nanotubos de carbono como absorvedor saturável. Os primeiros resultados foram obtidos de uma configuração experimental baseada totalmente em fibra monomodo padrão (SMF) com o laser operando próximo ao zero de dispersão da fibra em 1310 nm, porém em regime anômalo. Nesta mesma configuração, um estudo do encurtamento da duração do pulso em função do gerenciamento da dispersão intracavidade com comprimentos de fibra de dispersão deslocada (DSF) foi realizado. Substituindo a SMF por uma fibra altamente dopada com germânio como meio do ganho do laser Raman, a operação do laser foi deslocada para o regime de dispersão normal e o regime de acoplamento passivo de modos também foi gerado. Neste laser, um estudo do encurtamento da duração do pulso em função da redução do comprimento do meio de ganho foi realizado e a operação do acoplamento passivo de modos do laser em regime de picossegundos pôde ser estimada. Também apresentamos uma breve comparação entre os dois regimes de dispersão do laser Raman à fibra e resultados do acoplamento passivo de modos obtidos com diferentes diâmetros de nanotubos de carbono como absorvedores saturáveis.
Olmedo, Herrero Elena. "Étude des effets non linéaires dans les lasers et amplificateurs de puissance à fibre double gaine dopée Er3+/Yb3+." Phd thesis, Télécom ParisTech, 2003. http://pastel.archives-ouvertes.fr/pastel-00000743.
Повний текст джерелаGoutaland, François. "Processus multiphotoniques, défauts ponctuels et mécanismes de leur formation dans les fibres optiques : étude par spectroscopie laser." Saint-Etienne, 1998. http://www.theses.fr/1998STET4021.
Повний текст джерелаAparanji, Santosh. "Power Combining of Raman Fiber Lasers." Thesis, 2020. https://etd.iisc.ac.in/handle/2005/5111.
Повний текст джерелаMHRD
Balaswamy, Velpula. "High power Cascaded Raman fiber lasers." Thesis, 2018. https://etd.iisc.ac.in/handle/2005/4731.
Повний текст джерелаArun, S. "Continuous-Wave Supercontinuum Generation using Cascaded Raman Fiber Lasers." Thesis, 2018. https://etd.iisc.ac.in/handle/2005/4888.
Повний текст джерелаChoudhury, Vishal. "Raman and Brillouin Nonlinearities in High Power Fiber Lasers: Novel Effects and Applications." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5563.
Повний текст джерелаSchröder, Jochen 1976. "Raman scattering and four-wave mixing: from fundamentals to fibre lasers." 2009. http://hdl.handle.net/2292/4269.
Повний текст джерелаKrause, Michael [Verfasser]. "Efficient Raman amplifiers and lasers in optical fibers and silicon waveguides : new concepts / von Michael Krause." 2007. http://d-nb.info/994801556/34.
Повний текст джерелаLeung, Ka-Hei, and 梁家熙. "The Study of tunable spacing multi-channel hybrid Raman/EDF fiber laser with Double Pass Mach Zehnder Interferometer." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/39303046451440942215.
Повний текст джерела國立東華大學
光電工程研究所
98
In this paper we presented a multi-wavelength fiber laser structure using a MZI (Mach Zehnder Interferometer) to tune the wavelength spacing. The investigation is mainly in the researches of Mach Zehnder Interferometer structure, resonance cavity structure and gain medium. In the design of interference of Mach Zehnder Interferometer, we employed a manual OVDL (Optical Variable Delay Line) to change the phase difference in two optical paths, so the channel spacing of laser would continuously be tuned from 0.2nm to 1.9nm. We not only designed the tunability of Mach Zehnder Interferometer, but also improved the SNR (Single to Noise Ratio) of interference from 9.7dB to 18.8dB in our Double pass Mach Zehnder Interferometer, which led to the SNR of lasing channels can be over 50dB above in the spacing range. In our ring cavity and linear cavity laser experiments, as the ring cavity structure of which the wave was travelling in one direction while the linear cavity structure of which the wave was back and forth to form a standard wave, so the different resonance properties affected the number of lasing channels. For example, the channel spacing 0.2nm of Erbium Doped Fiber Laser which has only 5 channels in the ring cavity structure, whereas the linear cavity structure could generate 9 lasing channels. Therefore, compared between different laser structures, the linear structure multi-wavelength laser could effectively increase the number of channels. Moreover, we employed the different gain mediums with an EDF (Erbium Doped Fiber), a DCF (Dispersion Compensation Fiber) and a hybrid fiber in the laser structure. The hybrid fiber consisted of an erbium doped fiber and a Raman fiber. In the EDF fiber laser which the EDFA consisted of a 5.58m erbium doped fiber. Although the laser has higher gain and higher SNR, it also has serious homogeneous line broadening and strongly mode competition. So it was difficult to reach multi-wavelength and flat output. For example, the laser output only contained 9 lasing channels and ±4.75dB flatness in the spacing 0.2nm. In the Raman gain fiber laser experiment, the number of lasing channels could reach to 33 and ±4.07dB flatness in spacing 0.4nm, which the RFA consisted of a 4.47km dispersion compensation fiber and it belongs to inhomogeneous broadening mechanism. However, it was limited by the pumping power which led to not sufficient Raman gain to support a large portion of channels over the laser threshold, when the channel spacing was 0.2nm. In the Hybrid gain medium, we focused on the suitable pumping wavelength and the pumping power, because we could clearly understand that these would affect the number of lasing channels and the flatness. In the first experiment, the hybrid gain laser which had a few lasing channels and it was even fewer than the Raman laser when it was pumped by 977.3nm and 1465nm. In the end of our experiment, thereby we designed only two pumping wavelengths, which were 977.3nm and 1480nm, to generate more lasing channels and great flatness output effectively. For example, the number of lasing channels could increase up to 60 with operating channel spacing of 0.2nm, the lasing bandwidth was 12.9nm and the flatness was ±4.2dB.
Chang, I.-Feng, and 張宜豐. "Numerical Study of Maximum Extractable Energy from Multi-mode Pulsed Fiber Laser Amplifier with Considerations of Stimulated Raman Scattering." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/11195779836976584700.
Повний текст джерела國立中央大學
物理學系
103
A numerical study of maximum extractable energy from multi-mode pulsed fiber laser amplifier with considerations of stimulated Raman scattering is presented. Based on rate-propagation equations, a one-dimensional convection code is constructed for calculating the maximum extractable energy in fiber laser amplifiers. In order to derive the dispersion relations of fibers, the effective core area, overlapping integral with considerations of radial-dependence distribution of gain medium, and eigenvalue equations with weakly-guide approximation are also solved using the numerical approach. In the thesis, we extended the single-mode model, which is based on rate-propagation equation, to study the maximum extractable energy in fiber laser amplifiers with a large fiber core. Simulation results show that the criterions of seed energy and input seed pulse width to extract maximum energy in fiber laser amplifiers are determined by the nonlinear phenomenon and multimode effects. The numerical model used in the study can be applied to study the nonlinear effects and the spectral broadening in a large-mode-area (LMA) fiber and provide experimental designs of a practical high-power and high-energy pulsed fiber amplifier.
Chang, Wei-cheng, and 張惟程. "Noise like pulses with broad spectrum bandwidth from a passive mode-locked Yb-doped fiber laser based on stimulated Raman scattering." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8a935d.
Повний текст джерела國立臺北科技大學
光電工程系研究所
105
We investigated the soliton dynamics in passive mode-locked Yb-doped fiber lasers (PML-YDFL) based on nonlinear polarization rotation mechanism (NPR). Once laser was mode-locked, the noise-like pulses were produced that revealed double-scale intensity autocorrelation (IAC) trace. After adding a single mode fiber (HI1060) inside laser cavity to elongate cavity length in this fiber laser, the threshold power for Raman scattering can be efficiently reduced to produce a stimulated Raman scattering without an external power amplification system. In this work, the generated mode-locked pulses with the broadest spectrum bandwidth can be produced after insertion of 150 meters single mode fiber (SMF) inside laser cavity. The spectrum evolution as a function of pump power was monitored with an additional 150 m SMF inside cavity. At the pump power of 241 mW, the second order Raman spectrum with peak wavelength at 1135 nm was generated. In addition, we also compared the speckle image of laser operation at CW, NLP and stimulated Raman state. Furthermore, we demonstrate that the speckle image can be further enhanced after connection a 5 meters long multi-mode fiber to excite higher order modes. The lowest contrast less than 0.04 can be produced in operation at stimulated Raman state with extension of spectrum from 1000 to 1160 nm.
Κοϊμτζόγλου, Χρήστος. "Μελέτη της επίδρασης της κόπωσης στη διεπιφάνεια ίνας/μήτρας σύνθετων υλικών οργανικής μήτρας και της επίδρασης του φαινομένου στους μηχανισμούς μεταφοράς φορτίων σε μικροσκοπικό επίπεδο, με τη μέθοδο laser Raman spectroscopy". Thesis, 2003. http://hdl.handle.net/10889/8758.
Повний текст джерелаOne of the most important parameters that affect the mechanical response of composites is the quality of the interfacial bond between the matrix and the reinforcing material. Therefore, the aim of the present work is to investigate the effect of fatigue loading on the integrity of the interfacial bond in fibre-reinforced plastics in microscopic level using the laser Raman spectroscopy technique.