Amplification of Short Laser Pulses via Resonant Energy Transfer in Underdense Thermal Plasmas

Tyan-Lin Wang
Advisor: Chandrasekhar Joshi

Monday, August 23, 2010 at 2:00pm
Engr IV Room 57-124

Abstract:
Resonant energy transfer between two laser beams based on the stimulated Raman scattering (SRS) process in underdense thermal plasmas is studied in the context of being a potential mechanism to amplify laser pulses. We demonstrate experimentally the amplification of picosecond-scale seed laser pulses by a nanosecond pump laser pulse inside a millimeter-scale plasma with density such that the plasma frequency satisfies the resonance condition for energy transfer. We then compare the experimental results to simulation results from 1D Particle-In-Cell (PIC) and 2D envelope three wave model codes. Along with the prospect of obtaining amplification, there are adverse physical effects in the plasma such as SRS noise, absorption and self-focusing of the laser beams, and plasma kinetic behavior leading to detuning from resonance and saturation of the gain. We discuss these issues as they arise in both the experimental and simulation results and show how they can place limitations on the peak intensity and beam quality that can be achieved. Possible ideas for mitigating some of these physical restrictions will be given.

Biography:

Tyan-Lin Wang received his B.S. and M.S. degrees in Electrical Engineering from UCLA in 2002 and 2004, respectively. He is currently a Ph.D. candidate in the Electrical Engineering department at UCLA.