Amplification of mode-locked Nd:Yag/Nd: glass lasers for high power diagnostic and heating applications

Solid state lasers have usually been operated in short, high peak power pulses with large pulse spacing, or CW with a much lower maximum power. The basis of this work was to try to obtain higher power and energy levels for a relatively long period of time by amplifying a mode-locked pulse train rather than a single high energy pulse or a CW beam. This method attempted to take advantage of the higher efficiency energy extraction of a higher peak power, while not depleting the inversion in the amplifier too quickly, thus allowing a longer and more uniform output. One possible application of this system is multipulse Thomson scattering plasma diagnostics. The pulse repetition frequency of the mode-locked system is 100 MHz, allowing much better temporal resolution. The output of the system may be frequency doubled to 0.532μm which is currently favored because of detector sensitivity in that range. Also, gas heating studies for research on laser propulsion of spacecraft have used CO2 lasers (10.6μm) with high power, high energy output, which in general been large instruments. However, the atmospheric transmission window at 2um would make the shorter wavelength advantageous, and a smaller instrument more amenable to manipulation