Diode pumped fiber laser

Work conducted in the area of single crystal fiber optical devices is described. Miniature Nd:YAG 1.32 micron lasers were fabricated using both free space (unguided) and single crystal fiber configurations. Bulk lasers with thresholds as low as 19 mw and near optimum slope efficiencies of 36% were demonstrated. Several guided fiber lasers were also successfully brought to oscillation. The best device has a threshold of 12 mw, a slope efficiency of 22%, and a maximum recorded output power at 1.32 micrometers of 22 mw. Fiber scattering properties inferred from these measurements indicate that the crystal fiber used in this work exhibit a much higher quality than the fibers used in earlier phases of this work as a result of improved growth conditions. A theoretical investigation of 1.32 micrometers optically-pumped lasers was also developed for interpretation of experimental data. A feasibility study of Q-switched fiber lasers operating near lambda = 1.06 micrometers was also conducted. Theoretical expressions for the laser output peak power, pulse width and energy were cast in a simple form by implementing the formalism of normalized mode overlap coefficient introduced earlier in this work. Peak powers on the order of 100 to 500 watts and pulse widths of a few nanoseconds are anticipated for fiber lasers were also reviewed and compared to provide a recommended guideline for future laser work.