Pulse Shaping Effects in Optical Parametric Amplifications

An optical parametric amplifier (OPA) can provide laser amplification over a much larger spectral bandwidth than current amplifiers used in the OMEGA laser system. The OMEGA laser system is located at the University of Rochester Laboratory for Laser Energetics (LLE) which is where the work for this project was performed. Wider spectral bandwidth is advantageous for laser pulse smoothing techniques such as smoothing by spectral dispersion (ssD)~. An OPA could replace an OMEGA regenerative amplifier and possibly a Large Aperture Ring Amplifier (LARA), both of which are used in the "front e n d of the OMEGA laser system, if its output pulse shape and stability were suitable for injection into the main OMEGA laser chain. In the optical parametric amplification process, a "pump " laser pulse transfers its energy to a "seed" laser pulse through a nonlinear interaction in a crystalline material. A numerical computer model was used to determine the input pulse shapes required to obtain a specific desired output pulse shape (the shape that after going through the main OMEGA laser chain would produce the "alpha308 " shape). A two-crystal system that can create the desired output pulse shape is presented. To the best of my knowledge, this is the first time an OPA has been shown to be able to produce the highly shaped pulses necessary for Inertial Confinement Fusion lasers. A tradeoff between output pulse stability and input pulse contrast ratio is described. I