UC San Diego

Lasers are fundamental to our society and are used in an ever-increasing range of fields including manufacturing, communications, defense and medical industries. One of the main drivers in laser development is increasing laser power. This work presents the development of a new polycrystalline transparent ceramic material that shows promise as a high-power laser gain media. In addition, the development of materials specifically designed for fundamental laser-material interaction studies on lab scale as well as high energy, facility scale lasers is presented. The power deliverable by a laser scales directly with the thermal conductivity of the laser gain material. Aluminum oxide (hexagonal, Al2O3) has a higher thermal conductivity than any rare-earth host media available today thus synthesis/processing methods for obtaining high quality rare-earth doped alumina ceramics are of high interest. This work explores the impact of powder processing and densification conditions on the optical properties of ytterbium doped Al2O3 ceramics. Dopant incorporation methods and processing temperatures are explored to find the highest density ceramics possible. The first reported transparent ytterbium doped nanocrystalline alumina is characterized and discussed. The absorption and emission cross sections as well as upper state lifetime show promise for Yb:Al2O3 as a laser gain material. This work also presents target fabrication methods for high intensity laser-material interaction studies. The target materials are metals (aluminum) and semiconductors (silicon). The targets have been used in collaborative campaigns at lab and facility scale lasers at intensities up to 1014 W/cm2. In addition a study of silicon material damage as a function of intensity is presented. These experiments show that laser irradiation primarily results in melting at intensities up to 1013 W/cm2.