Lithium Niobate Miniature Lasers and Single-Crystal Fibers.

LiNbO_3 is a widely used optical material because of its excellent electro-optic and non-linear properties. By doping LiNbO_3 with an active ion such as Nd, laser oscillation and amplification are added to the panoply of LiNbO _3 device possibilities. Furthermore, by providing LiNbO_3 devices with the waveguide confinement of single-crystal fibers, their performance can be significantly improved. Chapter 1 introduces the subject of this dissertation. Chapter 2 is devoted to miniature continuous-wave Nd:MgO:LiNbO _3 lasers. Important results of our work are the first demonstration of room-temperature, true continuous-wave laser oscillation in Nd-doped LiNbO _3 and the first demonstration of diode-pumped laser action in this material. The Nd:MgO:LiNbO _3 lasers exhibited pump power thresholds (1.9 mW) and slope efficiencies (45%) that are among the state-of-the-art in solid state lasers. The attained power coupling to single-mode glass fibers (50%) is far superior to the coupling achievable with conventional laser diodes (15%). Chapter 2 also contains a detailed study on photoconductivity. It explains how the addition of MgO eliminates "photorefractive damage.". Chapter 3 studies Q-switched laser operation in Nd:MgO:LiNbO_3. Q-switching consists of generating very intense, nanosecond pulses by rapidly switching the cavity loss. The first integration of an electro-optic cell and a laser medium was achieved in the "Active Internally Q-switched Laser," which generated 5 Watt, 30 nanosecond pulses. We developed a theory of Q -switching with spatially non-uniform gain saturation and showed that its predictions are closer to the experimental observations than the predictions of conventional Q-switched laser theory. (Abstract shortened with permission of author.).