Theoretical and Experimental Foundations of Coherent Pulse Stacking Amplification

Abstract:

Coherent combining of fiber lasers has the potential to be the system of choice for next generation high peak power high average power laser systems, which could enable a myriad of new scientific and industrial applications. These fiber based systems have inherently good average power handling capabilities; however, new technologies are required in order to boost the pulse energy into the desired range. This thesis focuses on a novel time domain coherent combining technique called coherent pulse stacking amplification which has the ability to increase the pulse energy by two orders of magnitude for each fiber.

In this thesis, we develop the theoretical and experimental foundations of the coherent pulse stacking amplification (CPSA) technique. We build up the theoretical framework behind CPSA, which is based on the concept of coherently combining (a.k.a. stacking) a burst of pulses in the time domain into a single pulse. We give a recipe for how to design such a burst of pulses and a recipe for how to design the system of interferometers that can stack such pulses. We propose a method to stabilize these interferometers and also develop the theory for how this stabilization method performs in the presence of environmental noise sources. We also give several options for the spatial arrangement of these interferometers and mathematically analyze the pros and cons of each option. Finally we perform several proof-of-principle experiments in order to illustrate the efficacy of CPSA. These experiments show that a burst of up to 81 pulses can be stacked into a single pulse and that such a burst can have a total energy that is nearly two orders of magnitude more than what can be obtained with a single pulse without using CPSA.