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 solid state lasers. Double-tungstate crystal of neodymium-doped potassium gadolinium tungstate (Nd:KGW) is one of the most effective active media used in DPSS lasers for generation of continuous wave radiation and ultrashort (i.e. picosecond, 10-12 s) pulses. Unfortunately, the thermal conductivity of KGW host crystals is relatively low (~3 Wm-1K-1). This low thermal conductivity and large quantum defect while pumping with ~808 nm lead to significant thermo-optical distortions. One way to minimize thermo-optical distortions is to reduce the quantum defect. This can be done by pumping at longer wavelengths as compared to conventional 808 nm. In this work we demonstrate what we believe is the first continuous wave Nd:KGW laser with hot band diode pumping at ~910 nm. This pumping wavelength reduced the quantum defect by >46% as compared to the conventional ~808 nm pumping and resulted in significantly lower thermal lensing. The laser produced 2.9 W of average output power at 1067 nm in a diffraction limited beam for an absorbed pump power of 8.3 W. The slope efficiency and optical-to-optical efficiency were found to be 43% and 35%, respectively. Significant reduction of quantum defect offered by this pumping wavelength and availability of suitable high power laser diodes opens an attractive way to further power and efficiency scaling of the Nd:KGW lasers. / October 2016

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by Ng Chi Shing. / Chinese title in romanization: Shao sheng bo zai deng li zi ti guan dao nei di fei fa san zhuan bo. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Bibliography: leaf 70.

by Hung Wing-yiu. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1988. / Bibliography: leaves 98-103.

by Loi Kwok Kwong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 197-222). / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- An Overview of Integrated Optics --- p.1 / Chapter 1.2 --- Application of Lithium Niobate Integrated Optical Circuit --- p.4 / Chapter 1.3 --- Summary --- p.5 / Chapter Chapter 2 --- Optical Waveguide Theory --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Ray Optics Treatment of Planar Waveguide --- p.7 / Chapter 2.2.1 --- Step-index Waveguide --- p.8 / Chapter 2.2.2 --- Graded-index Waveguide --- p.13 / Chapter 2.3 --- Optical Channel Waveguide --- p.20 / Chapter 2.3.1 --- Marcatili's Method --- p.22 / Chapter 2.3.2 --- Effective Index Method --- p.26 / Chapter 2.4 --- Summary --- p.30 / Chapter Chapter 3 --- Waveguide Fabrication Technology --- p.32 / Chapter 3.1 --- Properties of Substrate Materials --- p.32 / Chapter 3.1.1 --- Glass --- p.32 / Chapter 3.1.2 --- Semiconductor --- p.34 / Chapter 3.1.3 --- Ferroelectric Material --- p.35 / Chapter 3.2 --- Waveguide Fabrication Techniques --- p.40 / Chapter 3.2.1 --- Ion Implantation --- p.40 / Chapter 3.2.2 --- Titanium Indiffusion --- p.41 / Chapter 3.2.3 --- Proton Exchange --- p.44 / Chapter 3.3 --- Summary --- p.48 / Chapter Chapter 4 --- Fabrication and Measurement of Optical Waveguides --- p.49 / Chapter 4.1 --- Fabrication of Optical Waveguides --- p.49 / Chapter 4.1.1 --- Planar Waveguides --- p.49 / Chapter 4.1.1.1 --- Substrate Cutting --- p.49 / Chapter 4.1.1.2 --- Substrate Cleaning --- p.49 / Chapter 4.1.1.3 --- Proton Exchange --- p.50 / Chapter 4.1.1.4 --- Post-exchange Annealing --- p.51 / Chapter 4.1.2 --- Channel Waveguides --- p.51 / Chapter 4.1.2.1 --- Patterning Technique: Photolithography and Lift-off --- p.51 / Chapter 4.1.2.2 --- Proton Exchange and Annealing --- p.56 / Chapter 4.1.2.3 --- Lapping and Polishing --- p.56 / Chapter 4.2 --- Measurement of Waveguide Parameters --- p.57 / Chapter 4.2.1 --- Coupling of Light into Optical Waveguide --- p.57 / Chapter 4.2.1.1 --- Prism Coupling --- p.58 / Chapter 4.2.1.2 --- End-fire Coupling --- p.60 / Chapter 4.2.2 --- Effective Index --- p.63 / Chapter 4.2.3 --- Refractive Index Profile --- p.63 / Chapter 4.2.4 --- Waveguide Depth --- p.67 / Chapter 4.2.5 --- Propagation Loss --- p.67 / Chapter 4.2.6 --- Near-field Intensity Profile --- p.69 / Chapter 4.3 --- Summary --- p.74 / Chapter Chapter 5 --- Results and Discussions --- p.75 / Chapter 5.1 --- Proton-exchanged Waveguides Using Phosphoric Acid --- p.75 / Chapter 5.2 --- Proton-exchanged LiNb03 Waveguides Using Toluic Acid --- p.112 / Chapter 5.3 --- Proton-exchanged LiNb03 Waveguides Using Stearic Acid --- p.127 / Chapter 5.4 --- Proton-exchanged LiNb03 Waveguides Using Cinnamic Acid --- p.148 / Chapter 5.5 --- Structural Characteristics of Proton-exchanged Waveguides --- p.174 / Chapter 5.5.1 --- Thermogravimetric Analysis --- p.174 / Chapter 5.5.2 --- Raman Spectroscopy --- p.174 / Chapter 5.5.3 --- Infrared Spectrometry --- p.179 / Chapter 5.5.4 --- Double Crystal X-ray Diffractometry --- p.185 / Chapter 5.6 --- Summary --- p.190 / Chapter Chapter 6 --- Conclusions --- p.192 / References --- p.197 / Chapter Appendix 1 --- Error Estimations --- p.219 / Chapter Appendix 2 --- List of Publications --- p.221

Au-Yeung, Kin Chung = 以光學模擬量子自旋和機械鐘擺的相互作用 / 歐陽健聰. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 80-81). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese. / Au-Yeung, Kin Chung = Yi guang xue mo ni liang zi zi xuan he ji xie zhong bai de xiang hu zuo yong / Ouyang Jiancong.

We prove the existence of a one-parameter family of solutions of the porous medium equation, a nonlinear heat equation. In our work, with space dimension 3, the interface is a half line whose end point advances at constant speed. We prove, by using maximum principle, that the solutions are stable under a suitable class of perturbations. We discuss the relevance of our solutions, when restricted to two dimensions, to gravity driven flows of thin films. Here we extend the results of J. Iaia and S. Betelu in the paper "Solutions of the porous medium equation with degenerate interfaces" to a higher dimension.

by Chan Lai Yin, Simon. / "December 1998." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references. / 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.

As an effective compact coherent light source, distributed feedback (DFB) waveguide laser has attracted much attention recently. Sol-gel Mass synthesized at low temperatures is a very useful optical material. DFB waveguide lasers based on sol-gel glasses were experimentally and theoretically investigated in this thesis. In addition, microring lasers based on a conjugated polymer, which is emerging as an important class of laser material, were also studied in this thesis. / DFB lasing characteristics of various dyes in zirconia waveguides and in solutions were investigated. Intensity modulation and polarization modulation were used to generate the laser action. The laser output showed different polarization characteristics and threshold energy variation when the feedback mechanism was changed from intensity modulation to polarization modulation. In addition, near infrared (NIR) wide-band tuning DFB lasing operation was achieved in NIR dve-doped sol-gel waveguides by using intensity modulation. / Microring cavities were fabricated by depositing poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene) (MEH-PPV) on glass fibers by a dip coating method. Laser emissions in whispering gallery modes using microring cavities were observed by pumping with a frequency-doubled Nd:YAG laser. The threshold energy of the MEH-PPV microring laser was as low as 10 nJ per pulse. The polarization characteristics of the microring lasers were studied and a polarization model was developed to explain the observed phenomena. / Theoretical expressions for the angle-dependent coupling coefficients of DFB lasers were derived to explain the polarization properties of the DFB lasers. The coupling and gain coefficients of the two orthogonal polarization components of DFB lasers are strongly dependent on the intersection angle and the polarization states of the two crossing pump heams. The experimental results of DFB lasing in dye solutions have verified our theoretical predictions. / Titania zirconia organically modified silicate (TiO2-ZrO 2-ORMOSIL) DFB waveguide lasers were demonstrated. The output polarization and output wavelength of TiO2-ZrO2-ORMOSIL DFB waveguide lasers were found to be dependent on the polarization of the crossing pump beams from a frequency-doubled Nd:YAG laser. Up to sixteen Output wavelengths corresponding to eight pairs of polarized output from eight propagation modes were observed simultaneously for a planar waveguide with a thickness of 6.7 mum. / Two-photon-pumped DFB lasing action with a narrow linewidth output was demonstrated in zirconia waveguides doped with trans-4-[p-( N-hydroxyethyl-N-methylamino)styryl]-N-methylpyridinium p-toluene sulfonate a compound that shows strong two-photon upconverted emission around 620 nm. Transient gratings for coherent scattering were generated in the waveguides by crossing two 1.06 mum beams. DFB laser emission with the linewidth as narrow as 60 pm was observed. Operating at the third-order Bragg condition, tunable TE mode laser emission was achieved from 618 to 640 nm. TM output modes from the DFB laser were observed when the crossing beams were changed from s-polarized to p-polarized. / Wang Jun = 分佈反饋波導激光器的實驗與理論研究 / 王俊. / "September 2006." / Adviser: King Young Wong. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1702. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 165-183). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307. / Wang Jun = Fen bu fan kui bo dao ji guang qi de shi yan yu li lun yan jiu / Wang Jun.

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