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Raman Scattering in Optical Fibers OPTICAL FIBERS AS ACTIVE MEDIA FOR LASERS (Raman-Type and Tm-doped) THESIS SUBMITTED AS PARTIAL FULFILMENT OF REQUIREMENTS FOR OBTAINING THE DEGREE OF DOCTOR OF PHILOSOPHY IN THE FIELD OF SCIENCE (OPTICS) By MSc. Maribel Juárez Hernández Supervisors: Dr. Efraín Mejía Beltrán (CIO) Dr. Lelio de la Cruz May (UNACAR) January 2018 León Guanajuato, México Declaration I hereby declare that the investigations presented in this thesis have been carried out by me under the supervision of my advisors Dr. Efraín Mejía Beltrán and Dr. Lelio de la Cruz May. The work is original and has not been submitted in another thesis or dissertation to get a degree, similar or equal to the one intended to obtain here, or any other University or Institution. To my beloved family and my dear husband, for all their love and support; without whom none of my success would be possible. Acknowledgments I would like to thank my advisors Dr. Efraín Mejía Beltrán and Dr. Lelio de la Cruz May and express my sincere gratitude for their entire patient and helpful guidance through my PhD. degree; also acknowledge their time dedicated to this work, to their advices and corrections. Likewise, I would like to thank to my evaluation committee, Dr. Alexander Kir’yanov, Dr. Olivier Pottiez, and Dr. Verónica Vázquez García, for all their comments and suggestions. I also want to express my gratitude to all those who have been part of my professional and personal education; my family, teachers, friends and colleagues; apologizes for not naming everyone. This research was supported by Consejo Nacional de Ciencia y Tecnología (CONACYT) who provided me the scholarship No. 377309 and was the contributor to the project CB- 2011-01/166740 that made possible this thesis. Hence, we thank to CONACYT for this valuable support. Table of contents I. Motivations ...................................................................................................................... i II. Objectives ....................................................................................................................... i III. Summary ........................................................................................................................ ii Chapter 1: Raman scattering in optical fibers 1. Raman scattering ...................................................................................... 2 1.1 Introduction ....................................................................................................................2 1.2 Spontaneous Raman scattering .....................................................................................3 1.3 Stimulated Raman scattering .........................................................................................7 1.4 Raman gain spectrum ....................................................................................................8 1.5 Propagation equations for Raman scattering along an optical fiber .............................10 1.6 Propagation equations for a cascaded Raman fiber laser ............................................13 1.7 Raman fiber lasers and amplifiers ................................................................................14 1.8 Special fiber based Raman lasers and amplifiers ........................................................15 1.9 Distributed Raman vs. discrete REs doped amplifiers .................................................16 1.10 References ...................................................................................................................17 Chapter 2: Energy transfer mechanisms in a RFL under different cavity configurations 2. Energy transfer mechanisms in a Raman fiber laser ............................... 20 2.1 Abstract ........................................................................................................................20 2.2 Introduction ..................................................................................................................20 2.3 Experimental configurations .........................................................................................21 2.4 Results and discussion ................................................................................................22 2.5 Conclusion ...................................................................................................................27 2.6 Acknowledgment ..........................................................................................................27 2.7 References ...................................................................................................................27 Chapter 3: Second (1178 nm) and third (1242 nm) Stokes Raman fiber lasers without intermediate Stokes cavities 3. Second (1178 nm) and third (1242 nm) Stokes Raman fiber lasers without intermediate Stokes cavities ................................................................................. 30 3.1 Abstract ........................................................................................................................30 3.2 Introduction ..................................................................................................................30 3.3 Experimental methodology and Results .......................................................................32 3.4 Conclusions..................................................................................................................38 3.5 Acknowledgment ..........................................................................................................38 3.6 References ...................................................................................................................38 Chapter 4: Rare earth doped optical fibers 4. Rare earth doped optical fibers ............................................................... 41 4.1 Introduction ..................................................................................................................41 4.2 Electronic and optical properties of rare earths ............................................................42 4.3 Properties of ionized rare earths in crystals and glasses .............................................46 4.4 Comparison of RE doped- silicate and fluorozirconate based glasses .........................47 4.5 Features of Tm3+ doped fibers .....................................................................................51 4.6 Optical fibers as amplifiers and laser systems .............................................................54 4.7 Population dynamics for a three-level system ..............................................................56 4.8 Amplification and laser oscillation ................................................................................59 4.9 Optimal fiber length for fiber lasers ..............................................................................62 4.10 Acknowledgements ......................................................................................................65 4.11 References ...................................................................................................................65 Chapter 5: Red laser-diode pumped Tm3+: ZBLAN fiber laser 5. Red laser-diode pumped Tm3+: ZBLAN fiber laser .................................. 68 5.1 Abstract ........................................................................................................................68 5.2 Introduction ..................................................................................................................68 5.3 Theory, hypothesis and estimations .............................................................................70 5.4 Experiments .................................................................................................................73 5.5 Results and discussions ...............................................................................................75 5.6 Conclusions..................................................................................................................79 5.7 Acknowledgement ........................................................................................................79 5.8 References ...................................................................................................................79 Chapter 6: Short wavelength emission by up-conversion in a Tm3+: ZBLAN single and dual-diode-pumped optical fiber 6. Spectral analysis of short wavelength emission by up-conversion in a Tm3+: ZBLAN single and dual-diode-pumped optical fiber .................................... 83 6.1 Abstract ........................................................................................................................83 6.2 Introduction ..................................................................................................................83 6.3 Experimental configuration ...........................................................................................84 6.4 Results and discussions ...............................................................................................86 6.5 Physical model of the processes involved along an active optical fiber .......................89 6.6 Conclusions..................................................................................................................90 6.7 References ...................................................................................................................90 Outcomes: Conclusions, discussions, and future work
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