The research investigations have led to the development of an acousto-optic modulator for mode-locking the high pressure CO2 laser. Nanosecond pulses have been generated with peak powers of about 25 Megawatts, the high peak power resulting from low insertion loss Brewster-angled germanium modulator. A photon-drag detector with a response time of 0.3 nsec was also developed for observing the mode-locked pulses. The design of a solid-cathode double-discharge electrically pulsed CO2 laser is described. Preliminary studies of thin film GaAs waveguides for 10.6 micron wavelength radiation have been undertaken with a view to the development of future modulators. A continuing semi-empirical design approach has resulted in an operational, though still short-lived, flowing copper vapor laser based on a continuous evaporation-condensation flow cycle.