We analyze the scalability of diffraction-limited fiber lasers considering thermal, non-linear, damage and pump coupling limits as well as fiber mode field diameter (MFD) restrictions. We derive new general relationships based upon practical considerations. Our analysis shows that if the fiber's MFD could be increased arbitrarily, 36 kW of power could be obtained with diffraction-limited quality from a fiber laser or amplifier. This power limit is determined by thermal and non-linear limits that combine to prevent further power scaling, irrespective of increases in mode size. However, limits to the scaling of the MFD may restrict fiber lasers to lower output powers.

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A laser efficiency of 4.2% at 4.2-J output has been obtained from a self-sustained discharge-pumped XeCl laser using a novel high-voltage prepulse technique to provide efficient energy transfer from a low-impedance transmission line to the load. High-pressure discharge-pumped lasers now offer a reliable, efficient, and scalable alternative to e beams for many applications in the visible and ultraviolet regions of the spectrum.

We fabricated a novel quasi-phase-matched frequency converter, using a zigzag optical beam path in a thin, polished parallel plate. Second-harmonic generation experiments demonstrated angle-tuned output at 4.6 to 5.3mum in GaAs and 1.7 to 2.0mum in ZnSe crystals when pulsed infrared laser sources were used.

Results of atmospheric propagation for a high-speed, large-actuator-number adaptive optics system are presented. The system uses a microelectromechanical system- (MEMS-) based spatial light modulator correction device with 1024 actuators. Tests over a 1.35-km path achieved correction speeds in excess of 800 Hz and Strehl ratios close to 0.5. The wave-front sensor was based on a quadrature interferometer that directly measures phase. This technique does not require global wave-front reconstruction, making it relatively insensitive to scintillation and phase residues. The results demonstrate the potential of large-actuator-number MEMS-based spatial light modulators to replace conventional deformable mirrors.