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Thesis (MSc (Physics. Institute for Laser Research))--University of Stellenbosch, 2005. / This thesis consists of two parts: a discussion on diode-pumped solid-state lasers and a detailed description of the development of a diode-end-pumped Nd:YLF laser. A background motivation, which places this research area in perspective, is also given. Part One introduces solid-state lasers and their physics. The focus is on the Nd3+ active ion and describes its energy level structure as a typical four-level solid-state laser. An overview of optical pump sources for solid-state lasers is given, focussing on the construction, operation and advantages of diode lasers. It is motivated that diode-end-pumping solid-state lasers produce laser systems with the highest efficiency and diffraction limited beam quality. It is, however, emphasised that power scaling of diode-end-pumped solid-state lasers is problematic due to localised heat generation in the solid-state laser medium. The adverse effect of heat generation on the laser performance is also described. In the design of diode-endpumped solid-state lasers, the management of thermal effects is suggested as the approach to scale the output power of these lasers. Part Two of the thesis describes the design and the results of a novel high-power diode-end-pumped solid-state laser developed at the Laser Research Institute. The description of the design is split into three components: the laser material, the pump source and the laser resonator. The choice of laser material is motivated in detail, focussing on Nd:YLF’s advantage of having a very weak thermal lens when operated on the σ-polarization at 1053 nm. Its disadvantage of having a low fracture limit is also highlighted, but the approach to power scale it to the multi-10-watt level, with the use of low doping concentration, a low absorption pump wavelength, and a large pump beam, is described. It is further shown that this approach led to the development of a novel laser resonator, which allows a large fundamental mode in the laser material to match the large pump beam, and it can compensate for the astigmatic thermal lens in Nd:YLF. The experimental results of the high-power diode-end-pumped Nd:YLF laser are presented, showing the influence of doping concentration, output coupling efficiency and resonator adjustments on the continuous wave and Q-switched laser performance. It is shown that the optimum laser parameters were determined, resulting in the Nd:YLF laser producing more than 26 W of continuous wave output power with a close to diffraction limited beam quality (M2 < 1.4), and more than 3 mJ of energy per pulse at a repetition rate of 6 kHz when Q-switched. It is concluded that the powerscaling concept proved to be efficient and that further power scaling would be possible with this scheme.

by Lam King Shun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves [40-41]). / by Lam King Shun. / Acknowledgement --- p.i / Biographical Sketch --- p.ii / Abstract --- p.iii / Table of Contents --- p.iv / Chapter Chapter One --- Introduction --- p.1 / Chapter Chapter Two --- The Sol-Gel Derived Silica / Chapter 2.1 --- Introduction to the so-gel science --- p.3 / Chapter 2.2 --- The procedure of the silica formation --- p.5 / Chapter 2.3 --- During the sol-gel process --- p.7 / Chapter 2.4 --- The silica characterization --- p.12 / Chapter 2.4.1 --- Physical properties --- p.12 / Chapter 2.4.2 --- Optical properties --- p.13 / Chapter 2.5 --- Sample preparation --- p.15 / Chapter Chapter Three --- Laser Experiments / Chapter 3.1 --- Basic principle of dye laser --- p.16 / Chapter 3.2 --- Experimental procedure --- p.20 / Chapter 3.3 --- Data and discussion --- p.23 / Chapter 3.3.1 --- Spectral and temporal behaviour --- p.2 3 / Chapter 3.3.2 --- The performance of the sol-gel silica laser --- p.37 / Chapter Chapter Four --- Conclusions and Suggestions for Further Work --- p.39 / References

Zhu Xiao Lei. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 116-121). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The emphasis of this work has been in two areas of optical materials - the crystal-chemical development of new optical frequency converters and the synthesis and study of new hosts for Cr����� luminescence and lasing. A simple method has been developed to identify promising frequency-doubling materials containing triangular oxoanions by estimation of nonlinear susceptibilities. Implementation of this method and its results have generated predictive capabilities in determining the relationships among crystal structure, nonlinear properties, and threshold powers. The new noncentrosymmetric borate SrLiB���O������ is discussed; its structure is built from a 3-dimensional condensation of B���0��� units with channels alternately filled with Sr and Li atoms. From these studies, a prescription for new pyroborate frequency converters has been developed. The material CdC������C���H7NO���, has been synthesized and structurally characterized by single-ciystal X-ray diffraction. Three new alkaline-earth beryllium borates, built from unique 2- and 3- dimensional networks and frameworks, have been identified. The structure of SrBe���(B0���)��� consists of layers of composition [Be���(BO���)���] interleaved by Sr atoms. CaBeB���O��� is constructed from a Ca0��� polyhedral network and a beryllium borate network. In BaBe���(B0���)��� the structure is composed of a beryllium borate framework intermingled with a Ba-centered dodecahedral framework. Several materials with potential as hosts for Cr����� lasing have been analyzed. The structural study of the laser host LiSrAIF6 revealed the distortions at the Al site that contribute to the unique optical properties of the Cr����� -doped crystals. The family of solid state oxide A���MM'(B0���)��� is one of the largest families of oxide reported to date. Metal site preferences, disorder, solid solubility, and the interrelationship between this structure and the layered structure type of Ba���Sc(B0���)��� are detailed. An optimal synthetic procedure has been developed for these materials to provide pure, highly crystalline phases. Also, the structural and optical features of (Cr�����:) Sr���In(B0���)��� with A= Sr and M=M'= In have been studied. The material Sr���LilnB���O������, was discovered while searching for a suitable lithium borate flux for crystal growth of the compound Sr���In(B0���)���. / Graduation date: 1993

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xi, 121 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 106-107).

High power diode-pumped solid state (DPSS) lasers are a rapidly growing technology that is attractive for various applications in scientific and industrial fields. DPSS lasers are highly efficient, reliable and durable with superior beam quality when compared to flash-lamp pumped lasers. Double-tungstate crystals such as potassium yttrium tungstate Yb:KY(WO₄)₂ (Yb:KYW) are one of the most popular active materials used in DPSS lasers for generation of continuous wave radiation and ultrashort (i.e. femtosecond, 10⁻¹⁵ s) pulses with high average output power. The high pump power of laser diodes results in considerable heat generation in a laser crystal that in turn causes thermal lensing effect. Thermal lensing affects the performance and stability of a resonator, and plays an important role in limiting the output power and degrading the beam quality of solid state lasers. Despite these facts, no detailed studies of thermal effects in Yb:KYW lasers were reported to date. In this work thermal lensing in a diode-pumped Ng-cut Yb:KYW laser operating at the wavelength of 1.04 μm was characterized. A maximum output power of 3.5 W with a nearly diffraction limited output beam (M₂ < 1.2) was achieved under the absorbed pump power of 13.8 W. The focal lengths of the induced thermal lenses were obtained from the laser output beam size measurements at various incident pump power levels and ABCD matrix analysis. At maximum output power the focal length of the induced thermal lens was found to be 814 mm for the Nm direction (horizontal) and 144 mm for the Np direction (vertical). Thermal lens sensitivity factors were 1.26 m⁻¹/W and 0.32 m⁻¹/W for the Np and Nm directions, respectively. This highly astigmatic thermal lensing can be explained by strong anisotropy of thermo-optical properties of the crystal and its cooling geometry. In addition, the finite element analysis (FEA) method was employed to obtain the focal lengths of the induced thermal lens inside the crystal. Simulation results obtained from the theoretical model were compared to experimental data, and the accuracy of the model was verified. The results of this work are critical for practical design of the efficient and reliable Yb:KYW lasers with multi-Watt average output power.

High power diode-pumped solid state (DPSS) lasers are a rapidly growing technology that is attractive for various applications in scientific and industrial fields. DPSS lasers are highly efficient, reliable and durable with superior beam quality when compared to flash-lamp pumped lasers. Double-tungstate crystals such as potassium yttrium tungstate Yb:KY(WO₄)₂ (Yb:KYW) are one of the most popular active materials used in DPSS lasers for generation of continuous wave radiation and ultrashort (i.e. femtosecond, 10⁻¹⁵ s) pulses with high average output power. The high pump power of laser diodes results in considerable heat generation in a laser crystal that in turn causes thermal lensing effect. Thermal lensing affects the performance and stability of a resonator, and plays an important role in limiting the output power and degrading the beam quality of solid state lasers. Despite these facts, no detailed studies of thermal effects in Yb:KYW lasers were reported to date. In this work thermal lensing in a diode-pumped Ng-cut Yb:KYW laser operating at the wavelength of 1.04 μm was characterized. A maximum output power of 3.5 W with a nearly diffraction limited output beam (M₂ < 1.2) was achieved under the absorbed pump power of 13.8 W. The focal lengths of the induced thermal lenses were obtained from the laser output beam size measurements at various incident pump power levels and ABCD matrix analysis. At maximum output power the focal length of the induced thermal lens was found to be 814 mm for the Nm direction (horizontal) and 144 mm for the Np direction (vertical). Thermal lens sensitivity factors were 1.26 m⁻¹/W and 0.32 m⁻¹/W for the Np and Nm directions, respectively. This highly astigmatic thermal lensing can be explained by strong anisotropy of thermo-optical properties of the crystal and its cooling geometry. In addition, the finite element analysis (FEA) method was employed to obtain the focal lengths of the induced thermal lens inside the crystal. Simulation results obtained from the theoretical model were compared to experimental data, and the accuracy of the model was verified. The results of this work are critical for practical design of the efficient and reliable Yb:KYW lasers with multi-Watt average output power.

Thesis (Ph.D.) - University of St Andrews, March 2007.

Thesis (M.S. in Applied Physics and M.S. in Electrical Engineering)--Naval Postgraduate School, December 2002. / Thesis advisor(s): William B. Colson, Phillip E. Pace. "AD-A411 177." Includes bibliographical references (p. 81-83). Also available online.