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PublisherThe University of Arizona.
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AbstractMid-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.
Degree ProgramGraduate College
Degree GrantorUniversity of Arizona
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Laser pulse amplification through a laser-cooled active plasmaJones, Roger C.; Ghneim, Said Nimr, 1953- (The University of Arizona., 1988)Recent advances in experimental laser cooling have shown the possibility of stopping an atomic beam using the light pressure force of a counter-propagating laser wave. As an application to laser cooling, it is proposed to build a single frequency cesium laser that has a narrow linewidth. Laser cooling techniques are used to cool an atomic beam of cesium to an average velocity of 5 m/s, corresponding to a temperature of 0.2°K. Expressions of the basic forces that a laser wave exerts on atoms are derived according to a semi-classical approach. The experimental problems and methods of avoiding these problems are treated in detail. A computer Monte-Carlo simulation is used to discuss the feasibility of building the proposed laser. This simulation was done for an ensemble of 10,000 atoms of cesium, and it included the effects of the gravitational force and the related experimental variables. The possibility of building single frequency lasers that use a cooled medium of noble gases, and many other applications of laser cooling are briefly discussed at the end of this work.
High Power Single-Frequency 976 nm Fiber Laser Source and its Frequency Doubling for Blue Laser GenerationPeyghambarian, Nasser; Zhu, Xiushan; Wu, Jingwei; Norwood, Robert (The University of Arizona., 2019)High power compact and robust single-frequency all-fiber laser sources operating at 9xx nm have attracted significant attention because they can be used in a variety of applications including high-brightness low-noise single-mode pumps for neodymium (Nd3+), ytterbium (Yb3+), or erbium (Er3+)-doped lasers and nonlinear frequency converters for visible and deep-UV laser generation, atom cooling, remote sensing, and spectroscopy. So far, several 100-W-level fiber laser sources operating at around 980 nm have been demonstrated with Yb3+-doped photonic crystal fibers. However, all these laser sources have broad bandwidths, which constrain their use in many applications where single-frequency lasers with very narrow linewidths and very low noises are required. High power single-frequency fiber lasers are generally achieved with master oscillator and power amplifier (MOPA). In this dissertation, single-frequency Yb3+-doped silica and phosphate fiber amplifiers at 976 nm were investigated and the obstacles to develop high power 976 nm fiber amplifiers were studied and analyzed. A power-scalable 976 nm single-frequency MOPA laser source was developed by using a custom-designed large-mode-area Yb3+-doped phosphate fiber for the second stage amplifier and over 10 W continuous-wave output with a polarization extinction ratio of 20 dB was obtained. Further power scaling of the 976 nm fiber amplifiers has been discussed. The frequency doubling of the 976 nm single-frequency fiber laser was also demonstrated with a magnesium-doped periodically-poled lithium niobate (MgO:PPLN) crystal and over 500 mW single-frequency laser at 488 nm was obtained with single-pass second harmonic generation.
Thulium Doped Microsphere Laser and Fiber LaserPeyghambarian, Nassser N.; Wu, Jianfeng; Peyghambarian, Nassser N.; Kost, Alan; Jiang, Shibin (The University of Arizona., 2005)In this dissertation, the spectroscopic properties of thulium doped tellurite and thulium doped germanate glass are characterized. Absorption and emission spectra, lifetime, Fourier Transform Infrared Spectroscopy (FTIR), and thermo-gravimetric analysis are utilized to characterize the thulium doped tellurite bulk glass samples. Judd-Oflet theory, Fuchtbauer-ladenburg theory, Kushida's model, Burshtein's hopping model, Miyakawa's non-resonant energy transfer model are employed in ab-initio calculation of cross relaxation energy transfer. The fundamental mechanism of cross relaxation energy transfer is examined through ab-initio calculation and self-calibrating spectroscopy.Thulium doped tellurite glass microspheres are fabricated by spin casting technique. Single mode 2-mm laser is demonstrated from tellurite microsphere with high thulium doping concentration. General laser condition for self-terminating transition is discussed and concluded. Demonstration of 1.5-mm laser is achieved from a self-terminating transition of thulium doped in tellurite microsphere through a cooperative lasing technique.Highly efficient 1.9 micron fiber laser is demonstrated in thulium doped germanate fiber laser. The slope efficiency of the fiber laser is 58%, which indicates a quantum efficiency of 1.79. Single frequency laser operation at 1.9 micron has been successfully accomplished. A fiber based Fabry-Perot interferometer is utilized as a scanning filter to examine the single frequency operation. 4 W laser output has been achieved from a 40 cm long Tm-doped germanate double cladding fiber laser.