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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 diode-to-singlemode fiber butt-coupling and extremely-short-external-cavity laser diodes: Analysis, realization and applicationsHowe, Dennis G.; Sidorin, Yakov Sergeevich, 1966- (The University of Arizona., 1998)The butt-coupling of a Fabry-Perot semiconductor laser diode and a singlemode optical fiber was realized and characterized in the near field. A novel butt-coupling model was developed and found very effective in describing all physical phenomena that occur when the butt-coupling parameters are varied over a wide range. The strong external optical feedback to the laser diode cavity that is present at extremely-short separations between the laser diode and the fiber is advantageously used to realize an extremely-short external cavity laser diode. By varying the length of the external cavity, the operational characteristics of this external cavity laser diode are controlled in a predictable and repeatable manner; a wavelength tunable laser diode source based on this effect was developed and analyzed. Another realization of an extremely short external cavity tunable laser diode, based on a closely spaced external filter with variable characteristics, was demonstrated. A potential application of the butt-coupling technique for light collection in an optical recording head is discussed. The work presented here is a research tool that can be used to facilitate the design of extremely-short external cavity laser diodes, which in many ways are technologically novel.
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.
Developments of Narrow-Linewidth Q-switched Fiber Laser, 1480 nm Raman Fiber Laser, and Free Space Fiber AmplifierPeyghambarian, Nasser; Zhou, Renjie; Shi, Wei; Kieu, Khanh (The University of Arizona., 2011)In the first chapter, a Q-switched fiber laser that is capable of generating transform-limited pulses based on single-frequency fiber laser seeded ring cavity is demonstrated. The output pulse width can be tuned from hundreds of nanoseconds to several microseconds. This Q-switched ring cavity fiber laser can operate over the whole C-band. In addition, a theoretical model is developed to numerically study the pulse characteristics, and the numerical results are in good agreements with the experimental results. In the next chapter, a Raman fiber laser is developed for generating signal at 1480 nm. Initial experimental results has demonstrated generating of Raman laser at 1175 nm, 1240 nm, 1315 nm, and 1395 nm wavelength. Finally, a free space fiber amplifier is studied both theoretically and experimentally. The experimental work has demonstrated signal coupling efficiency up to 90% in the NP highly Er/Yb co-doped phosphate fiber.